Azeotropic and azeotrope-like compositions comprising dichloromethane and 1h,4h-octafluorobutane or a hydrofluoroether and use of the compositions as flash spinning agents

Abstract

The present invention relates to (i) an azeotropic or azeotrope-like composition comprising (1) dichloromethane and 1H,4H-octafluorobutane, or comprising (2) dichloromethane and 1-methoxynonafluorobutane, or comprising (3) dichloromethane and 1‑ethoxynonafluorobutane, (ii) a spin fluid for flash spinning comprising these azeotropic or azeotrope-like compositions and a polyolefin, and (iii) a process for the preparation of plexifilamentary fibrils of polyolefins using the spin fluid.

Description

TITLEAZEOTROPIC AND AZEOTROPE-LIKE COMPOSITIONS COMPRISING DICHLOROMETHANE AND 1H,4H-OCTAFLUOROBUTANE OR A HYDROFLUOROETHER AND USE OF THE COMPOSITIONS AS FLASH SPINNING AGENTSFIELD OF THE INVENTIONThe present invention relates to (i) an azeotropic or azeotrope-like composition comprising (1) dichloromethane and 1H,4H-octafluorobutane, or comprising (2) dichloromethane and 1-methoxynonafluorobutane, or comprising (3) dichloromethane and 1-ethoxynonafluorobutane, (ii) a spin fluid for flash spinning comprising these azeotropic or azeotrope-like compositions and a polyolefin, and (iii) a process for the preparation of plexifilamentary fibrils of polyolefins using the spin fluid.BACKGROUNDFlash spinning is a process for producing fibrils that involves the following steps: (i) dissolving a polymer in a composition comprising one or more solvents (often called a spin agent), at elevated temperature and pressure to form a homogeneous solution (often called a spin fluid), (ii) reducing the pressure sufficiently below the spin fluid's cloud point pressure (i.e., the pressure at which the spin fluid transitions from a clear solution to a cloudy, two-phase dispersion), while still maintaining sufficient pressure to prevent the spin fluid from reaching its bubble point pressure (i.e., the pressure at which the spin agent in the spin fluid begins to boil), (iii) releasing the resulting dispersion continuously through one or more orifices into a lower pressure region at or near atmospheric temperature and pressure so that the spin agent flash evaporates as it emerges from the one or more orifices, (iv) collecting the polymer which remains as a stream of fibrils, e.g., plexifilamentary fibrils, and (v) recovering the evaporated spin agent for re-use. Examples of flash spinning processes are disclosed in US 3,227,794.In a commercial flash spinning process, the spin agent's solvent properties and physical properties are critical. In particular, the solvent properties of the spin agent determine whether and under what conditions fibrils are produced in the flash spinning process, and the spin agent's physical properties impact the process for recovering and re-using the spin agent. The process for recovering spin agents typically involves a step in which the spin agent is condensed from the gas state to the liquid state, and it is preferred that the composition of the spin agent remains essentially constant during this step. This is inherent when spin agents comprise only one solvent but not when they comprise two or more solvents, which are often required to provide the necessary solvent properties for flash spinning the desired polymer. Accordingly, when using a spin agent that comprises two or more solvents, it is advantageous to use a composition that is azeotropic or azeotrope-like which behaves similarly to a spin agent with only one solvent.One example of a commonly used solvent for polymers such as polyolefins is dichloromethane (DCM). DCM, however, is a strong solvent for polyolefins and when mixed with polyethylene to form a spin fluid, the spin fluid fails to produce a cloud point pressure below temperatures of about 225°C. Likewise, when DCM is mixed with polypropylene, PB 1, or PMP to form a spin fluid, the spin fluid fails to produce a cloud point pressure at even higher temperatures. The use of DCM as a single spin agent is therefore not desirable to perform the flash spinning process at reduced temperatures following the description in US 3,227,794. Weaker solvents such as fluorinated compounds, hydrofluorocarbons, or hydrofluoroethers can be mixed with DCM to reduce the solvent strength of the spin agent and increase the spin fluid's cloud point pressure such that flash spinning can be readily accomplished for a wider range of temperature or polymers.WO 2016 / 200873 A1 suggests spin agent compositions of dichloromethane with 1H,6H-perfluorohexane, 1H-perfluorohexane, or 1H-perfluoroheptane. However, use of such linear C6 or C7 hydrofluorocarbons in combination with DCM results in spin agents that often exhibit undesirably high global warming potential (GWP). In view of the growing concerns regarding climate change and increasing regulatory requirements, it is desirable to find suitable spin agent compositions with a lower GWP. Such spin agent composition should also form a homogeneous liquid phase at ambient temperatures and pressures, rather than a heterogeneous liquid phase where, due to low miscibility of the components of the spin agent composition, a liquid phase separation occurs. Compositions forming heterogeneous liquid phases are usually undesired since processes involving such compositions are more complex and expensive due to the liquid phase separation.US 5,672,307 and US 5,977,237 report a flash spinning process using spin agent compositions of dichloromethane with cyclic perfluorocarbons, such as perfluoro-1,2-dimethylcyclobutane and perfluoro-N-methylmorpholine, or with various fluorobutyl- or fluoropropyl-ethers. US 7,300,968 reports a flash spinning process of polyethylene using a spin agent composition of dichloromethane and 1H, 4H-octafluorobutane in an 80:20 or 70:30 ratio by weight which is not azeotropic or near-azeotropic. US 10,329,692 B2 reports a flash spinning process of polyethylene using a spin agent composition of dichloromethane and 1-methoxynonafluorobutane in a 75:25 ratio by weight which is not azeotropic or near-azeotropic. However, the disclosed compositions complicate the spin agent recovery process since (i) many of the disclosed non-DCM components are not miscible with DCM at ambient temperatures and pressures, which results in a heterogeneous liquid phase of the non-DCM component and the DCM after condensation of the spin agent, i.e., to a liquid phase separation of the two components, and / or (ii) the disclosed compositions do not form an azeotropic or azeotrope-like composition at the specifically disclosed ratios. Where an azeotrope forms between DCM and the non-DCM component in the spin agent, it is beneficial if this is a positive azeotrope because the boiling point of the azeotrope is then lower than that of either individual component of the spin agent composition. This allows the low-pressure region into which flash spinning takes place (i.e., the spin-cell) to be maintained at a lower temperature without risking the spin agent condensing inside it. This also reduces the need for spin-cell heating and provides a more comfortable environment for operators working near the spin-cell. On the other hand, a negative azeotrope, which has a higher boiling point than that of either individual component of the spin agent composition, could require spin-cell heating which would lead to increased equipment and operating costs.Accordingly, there is a need for, and the present inventors have discovered, azeotropic and azeotrope-like compositions that (i) form a positive homogenous azeotrope with a boiling temperature below 40 °C, (ii) simplify the spin agent recovery and re-use process, and (iii) provide suitable cloud point pressures for flash spinning a broad range of different polymers and blends / mixtures thereof.SUMMARY OF THE INVENTIONIn one embodiment the invention is directed to an azeotropic or azeotrope-like composition comprising(1) dichloromethane and 1H, 4H-octafluorobutane,(2) dichloromethane and 1-methoxynonafluorobutane, or(3) dichloromethane and 1-ethoxynonafluorobutane.In one embodiment the invention is directed to an azeotropic or azeotrope-like composition comprising dichloromethane and 1H, 4H-octafluorobutane.In a further embodiment the invention is directed to an azeotropic or azeotrope-like composition comprising dichloromethane and 1-methoxynonafluorobutane.In a further embodiment the invention is directed to an azeotropic or azeotrope-like composition comprising dichloromethane and 1-ethoxynonafluorobutane.In a further embodiment the invention is directed to a spin fluid for flash spinning comprising (a) from about 6 to about 24 weight percent of a polyolefin, based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises (1) an azeotropic or azeotrope-like composition comprising dichloromethane and 1H,4H-octafluorobutane, or (2) an azeotropic or azeotrope-like composition comprising dichloromethane and 1-methoxynonafluorobutane, or (3) an azeotropic or azeotrope-like composition comprising dichloromethane and 1-ethoxynonafluorobutane.In a further embodiment the present invention is directed to a process for the preparation of plexifilamentary fibrils of polyolefin. The process comprises the steps of:(i) generating a spin fluid comprising(a) from about 6 to about 24 weight percent of a polyolefin, based on the total amount of the spin fluid, and(b) a spin agent, and(ii) flash-spinning the spin fluid at a pressure that is above the vapor pressure of the spin fluid into a region of essentially atmospheric pressure to form plexifilamentary fibrils of the polyolefin,wherein the spin agent comprises(1) an azeotropic or azeotrope-like composition comprising dichloromethane and 1H,4H-octafluorobutane,(2) an azeotropic or azeotrope-like composition comprising dichloromethane and 1-methoxynonafluorobutane, or(3) an azeotropic or azeotrope-like composition comprising dichloromethane and 1-ethoxynonafluorobutane.BRIEF DESCRIPTION OF THE FIGURESFig. 1 shows the calculated vapor-liquid equilibrium (VLE) for the compositions of dichloromethane (DCM) and 1H,4H-octafluorobutane (HFC-338pcc) at 40°C.Fig. 2 shows the cloud point pressure curve of a spin fluid comprising 10 wt% polypropylene (PP) and a spin agent of dichloromethane (DCM) and 1H, 4H-octafluorobutane (HFC-338pcc) in a 60:40 ratio by weight.Fig. 3 shows the cloud point pressure curve of a spin fluid comprising 18 wt% poly(4-methyl-1-pentene) (P4M1P) and a spin agent of dichloromethane (DCM) and 1H,4H-octafluorobutane (HFC-338pcc) in a 42:58 ratio by weight.Fig. 4 shows the calculated vapor-liquid equilibrium (VLE) for the compositions of dichloromethane (DCM) and 1-methoxynonafluorobutane (HFC-449mccc) at 40°C.Fig. 5 shows the cloud point pressure curve of a spin fluid comprising 7 wt% polypropylene (PP) and a spin agent of dichloromethane (DCM) and 1-methoxynonafluorobutane (HFC-449mccc) in a 54:46 ratio by weight.Fig. 6 shows the cloud point pressure curve of a spin fluid comprising 12 wt% polybutene-1 (PB-1) and a spin agent of dichloromethane (DCM) and 1-methoxynonafluorobutane (HFC-449mccc) in a 54:46 ratio by weight.Fig. 7 shows the cloud point pressure curve of a spin fluid comprising 20 wt% poly(4-methyl-1-pentene) (P4M1P) and a spin agent of dichloromethane (DCM) and 1-methoxynonafluorobutane (HFC-449mccc) in a 54:46 ratio by weight.Fig. 8 shows the calculated vapor-liquid equilibrium (VLE) for the compositions of dichloromethane (DCM) and 1-ethoxynonafluorobutane (HFC-569mccc) at 40°C.Fig. 9 shows the cloud point pressure curve of a spin fluid comprising 22 wt% polyethylene (PE) and a spin agent of dichloromethane (DCM) and 1-ethoxynonafluorobutane (HFC-569mccc) in a 76:24 ratio by weight.Fig. 10 shows the cloud point pressure curve of a spin fluid comprising 12 wt% ethylene-hexene copolymer and a spin agent of dichloromethane (DCM) and 1-ethoxynonafluorobutane (HFC-569mccc) in a 76:24 ratio by weight.Fig. 11 shows the cloud point pressure curve of a spin fluid comprising 10 wt% polypropylene (PP) and a spin agent of dichloromethane (DCM) and 1-ethoxynonafluorobutane (HFC-569mccc) in a 66:34 ratio by weight.Fig. 12 shows the cloud point pressure curve of a spin fluid comprising 15 wt% polybutene-1 (PB-1) and a spin agent of dichloromethane (DCM) and 1-ethoxynonafluorobutane (HFC-569mccc) in a 66:34 ratio by weight.Fig. 13 shows the cloud point pressure curve of a spin fluid comprising 22 wt% poly(4-methyl-1-pentene) (P4M1P) and a spin agent of dichloromethane (DCM) and 1-ethoxynonafluorobutane (HFC-569mccc) in a 66:34 ratio by weight.DETAILED DESCRIPTIONDefinitions and Clarification of TermsBefore addressing details of embodiments, some terms and test methods are defined or clarified. Unless otherwise mentioned, all tests were carried out without preconditioning of the samples. When average values are indicated herein, this refers to the arithmetic average.Density is determined according to the method described in ISO 1183 (Plastics - Methods for determining the density of non-cellular plastics).Melting point is determined by differential scanning calorimetry, following the guidance provided in ASTM D3418 (Standard Test Method for Transition Temperatures and Enthalpies of Fusion and Crystallization of Polymers by Differential Scanning Calorimetry) and ASTM Standard F2625 (Standard Test Method for Measurement of Enthalpy of Fusion, Percent Crystallinity and Melting Point of Ultra-High-Molecular weight polyethylene by means of differential scanning calorimetry). For polyethylene, heating and cooling is performed under inert gas at a rate of 10 °C / minute, heating the sample first from room temperature to 210 °C, then cooling the sample back to room temperature and subsequently heating the sample a second time to 210 °C. The melting point reported herein is the peak temperature of the endotherm of the second heating cycle. For polypropylene and polybutene-1, the same procedure applies - where the maximum temperature is 230 °C. For poly(4-methyl-1-pentene), the same procedure applies - where the maximum temperature is 300 °C.The melt flow rate is determined according to the method described in ISO 1133 (Plastics - Determination of the melt mass-flow rate (MFR) and the melt volume-flow rate (MVR) of thermoplastics). The melt flow rate for polyethylene is determined at a temperature of 190 °C and using a mass of 2160 grams (2.16kg), 5000 grams (5kg) or 21,600 grams (21.6kg). The melt flow rate for polypropylene is determined at a temperature of 230°C and using a mass of 2160 grams (2.16 kg). The melt flow rate for polybutene-1 is determined at a temperature of 190°C and using a mass of 2160 grams (2.16 kg). The melt flow rate for poly(4-methyl-1-pentene) is determined at temperature of 260°C and using a mass of 2160 grams (2.16 kg) or 5000 grams (5 kg).The term "polymer” is intended to embrace, without limitation, homopolymers, copolymers (such as for example, block, graft, random, and alternating copolymers), terpolymers, etc., and blends and modifications thereof. Furthermore, unless otherwise specifically limited, the term "polymer” shall include all possible geometrical configurations of the material. These configurations include, but are not limited to, isotactic, syndiotactic, and random symmetries.The term "polyethylene" is intended to embrace not only homopolymers of ethylene, but also copolymers and terpolymers wherein at least 85% of the recurring units are ethylene units, and the comonomer unit is for example propylene, butylene, hexene or octene. One useful polyethylene is a high-density polyethylene that has a melting point of about 123 °C to about 140 °C, a density of 0.94 to 0.98 grams per cubic centimeter (ISO 1183), and a melt flow rate (ISO 1133, 190 °C / 2160 grams) of between 0.05 g / 10min and 30 g / 10min, preferably less than 4 g / 10min, and / or a melt flow rate (ISO 1133, 190 °C / 21,600 grams) of between 1 g / 10min and 15 g / 10min. The polyethylene may contain up to about 10 weight percent or up to about 5 weight percent of other polymers, such as other polyolefins, for example polypropylene.The term "polypropylene" is intended to embrace not only homopolymers of propylene but also copolymers and terpolymers where at least 85% of the recurring units are propylene units. Furthermore, unless otherwise specifically limited, the term "polypropylene” shall include all possible geometrical configurations of the material. These configurations include, but are not limited to, isotactic, syndiotactic, and random symmetries. The polypropylene may contain up to about 10 weight percent or up to about 5 weight percent of other polymers, such as other polyolefins, for example polyethylene.The term "polymer type" refers to the chemical class into which the polymer falls, for example, polyolefin, polyethylene, polypropylene, etc.The term "plexifilamentary" refers to a three-dimensional integral network or web of a multitude of thin, ribbon-like, fibrils of random length and a median fibril width of less than about 25 microns. In plexifilamentary structures, the fibrils are generally coextensively aligned with the longitudinal axis of the structure, and they intermittently unite and separate at irregular intervals in various places throughout the length, width, and thickness of the structure to form a continuous three-dimensional network or web.The terms "spin agent" or "spin agent composition" refer to a composition comprising one or more solvents and any additives that are used to initially dissolve the polymer(s) to form the spin fluid. Suitable additives include stabilizers, such as antioxidants or acid scavengers.The term "spin fluid" refers to a solution for spinning in a flash spinning process comprising a polymer and a spin agent. The solution may also include one or more additives.The term "dew point pressure" refers to the pressure at which, at constant temperature, liquid starts condensing from a vapor, vapor mixture, or vapor-gas mixture.The term "bubble point pressure" refers to the pressure at which, at constant temperature, a liquid, liquid mixture, or liquid-solution begins to boil.The term "azeotropic composition" refers to a composition comprising two or more fluids wherein the bubble point pressure equals the dew point pressure. An azeotropic composition boils without change of the composition and behaves as a single substance. The azeotropic compositions described herein are determined in a temperature range of -20 °C to 100 °C and expressed in mass fractions.The term "azeotrope-like composition" refers to a composition comprising two or more fluids which exhibit only small differences between the dew point pressure and the bubble point pressure, i.e., the dew point pressure is different by 5% or less from the bubble point pressure (both expressed in absolute pressure). An azeotrope-like composition boils without substantial change of the composition and behaves substantially as a single substance. The azeotrope-like compositions described herein are determined in a temperature range of -20 °C to 100 °C and expressed in mass fractions.The term "cloud point pressure" refers to the pressure at which, at constant temperature, a clear single phase spin fluid transitions from a clear solution to a cloudy, two-phase dispersion. At the cloud point pressure, a clear spin fluid becomes turbid.Atmospheric pressure means 101.325 kPa. Essentially atmospheric pressure means 101.325 kPa ± 5%.As used herein, the singular forms "a," "an," and "the" include the plural, and reference to a particular numerical value includes at least that particular value, unless the context clearly dictates otherwise. When a range of values is expressed, another embodiment includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about," it will be understood that the particular value forms another embodiment. All ranges are inclusive and combinable.Azeotropic or Azeotrope-like CompositionsAzeotropic or azeotrope-like compositions comprising dichloromethane and 1H,4H-octafluorobutaneProvided herein are azeotropic or azeotrope-like compositions comprising dichloromethane and 1H,4H-octafluorobutane.In some embodiments, the azeotropic or azeotrope-like compositions comprise from about 18 to about 63 weight percent dichloromethane and from about 82 to about 37 weight percent 1H,4H-octafluorobutane, or from about 24 to about 54 weight percent dichloromethane and from about 76 to about 46 weight percent 1H,4H-octafluorobutane. These azeotropic or azeotrope-like compositions boil at a temperature of about -20 °C to about 100 °C and at a boiling pressure of about 8 kPa to about 715 kPa. In other embodiments, the azeotropic or azeotrope-like compositions comprise from about 24 to about 61 weight percent dichloromethane and from about 76 to about 39 weight percent 1H,4H-octafluorobutane, or from about 30 to about 53 weight percent dichloromethane and from about 70 to about 47 weight percent 1H,4H-octafluorobutane. These azeotropic or azeotrope-like compositions boil at a temperature of about -20 °C to about 60 °C and at a boiling pressure of about 8 kPa to about 249 kPa. In other embodiments, the azeotropic or azeotrope-like compositions comprise from about 29 to about 58 weight percent dichloromethane and from about 71 to about 42 weight percent 1H,4H-octafluorobutane, or from about 32 to about 52 weight percent dichloromethane and from about 68 to about 48 weight percent 1H,4H-octafluorobutane. These azeotropic or azeotrope-like compositions boil at a temperature of about -20 °C to about 40 °C and at a boiling pressure of about 8 kPa to about 131 kPa.In some embodiments, the azeotropic or azeotrope-like compositions consist essentially of from about 18 to about 63 weight percent dichloromethane and from about 82 to about 37 weight percent 1H,4H-octafluorobutane, or from about 24 to about 54 weight percent dichloromethane and from about 76 to about 46 weight percent 1H,4H-octafluorobutane. These azeotropic or azeotrope-like compositions boil at a temperature of about -20 °C to about 100 °C and at a boiling pressure of about 8 kPa to about 715 kPa. In other embodiments, the azeotropic or azeotrope-like compositions consist essentially of from about 24 to about 61 weight percent dichloromethane and from about 76 to about 39 weight percent 1H,4H-octafluorobutane, or from about 30 to about 53 weight percent dichloromethane and from about 70 to about 47 weight percent 1H,4H-octafluorobutane. These azeotropic or azeotrope-like compositions boil at a temperature of about -20 °C to about 60 °C and at a boiling pressure of about 8 kPa to about 249 kPa. In other embodiments, the azeotropic or azeotrope-like compositions consist essentially of from about 29 to about 58 weight percent dichloromethane and from about 71 to about 42 weight percent 1H,4H-octafluorobutane, or from about 32 to about 52 weight percent dichloromethane and from about 68 to about 48 weight percent 1H,4H-octafluorobutane. These azeotropic or azeotrope-like compositions boil at a temperature of about -20 °C to about 40 °C and at a boiling pressure of about 8 kPa to about 131 kPa.In some embodiments, the azeotropic or azeotrope-like compositions consist of from about 18 to about 63 weight percent dichloromethane and from about 82 to about 37 weight percent 1H,4H-octafluorobutane, or from about 24 to about 54 weight percent dichloromethane and from about 76 to about 46 weight percent 1H,4H-octafluorobutane. These azeotropic or azeotrope-like compositions boil at a temperature of about -20 °C to about 100 °C and at a boiling pressure of about 8 kPa to about 715 kPa. In other embodiments, the azeotropic or azeotrope-like compositions consist of from about 24 to about 61 weight percent dichloromethane and from about 76 to about 39 weight percent 1H,4H-octafluorobutane, or from about 30 to about 53 weight percent dichloromethane and from about 70 to about 47 weight percent 1H,4H-octafluorobutane. These azeotropic or azeotrope-like compositions boil at a temperature of about -20 °C to about 60 °C and at a boiling pressure of about 8 kPa to about 249 kPa. In other embodiments, the azeotropic or azeotrope-like compositions consist of from about 29 to about 58 weight percent dichloromethane and from about 71 to about 42 weight percent 1H,4H-octafluorobutane, or from about 32 to about 52 weight percent dichloromethane and from about 68 to about 48 weight percent 1H,4H-octafluorobutane. These azeotropic or azeotrope-like compositions boil at a temperature of about -20 °C to about 40 °C and at a boiling pressure of about 8 kPa to about 131 kPa.In some embodiments, the composition comprising dichloromethane and 1H,4H-octafluorobutane is azeotropic.In some embodiments, the azeotropic composition consists essentially of from about 38 to about 45 weight percent dichloromethane and from about 62 to about 55 weight percent 1H,4H-octafluorobutane. In some embodiments, the azeotropic composition consists of from about 38 to about 45 weight percent dichloromethane and from about 62 to about 55 weight percent 1H,4H-octafluorobutane. These azeotropic compositions boil at a temperature of about -20 °C to about 100 °C and at a boiling pressure of about 8 kPa to about 715 kPa.In some embodiments, the azeotropic composition consists essentially of about 45.0 weight percent dichloromethane and about 55.0 weight percent 1H,4H-octafluorobutane at a pressure of about 8.9 kPa and at a boiling temperature of about -20°C. In some embodiments, the azeotropic composition consists of about 45.0 weight percent dichloromethane and about 55.0 weight percent 1H,4H-octafluorobutane at a pressure of about 8.9 kPa and at a boiling temperature of about -20°C.In some embodiments, the azeotropic composition consists essentially of about 43.0 weight percent dichloromethane and about 57.0 weight percent 1H,4H-octafluorobutane at a pressure of about 62.0 kPa and at a boiling temperature of about 20°C. In some embodiments, the azeotropic composition consists of about 43.0 weight percent dichloromethane and about 57.0 weight percent 1H,4H-octafluorobutane at a pressure of about 62.0 kPa and at a boiling temperature of about 20°C.In some embodiments, the azeotropic composition consists essentially of about 42.0 weight percent dichloromethane and about 58.0 weight percent 1H,4H-octafluorobutane at a pressure of about 130.9 kPa and at a boiling temperature of about 40°C. In some embodiments, the azeotropic composition consists of about 42.0 weight percent dichloromethane and about 58.0 weight percent 1H,4H-octafluorobutane at a pressure of about 130.9 kPa and at a boiling temperature of about 40°C.In some embodiments, the azeotropic composition consists essentially of about 40.7 weight percent dichloromethane and about 59.3 weight percent 1H,4H-octafluorobutane at a pressure of about 248.7 kPa and at a boiling temperature of about 60°C. In some embodiments, the azeotropic composition consists of about 40.7 weight percent dichloromethane and about 59.3 weight percent 1H,4H-octafluorobutane at a pressure of about 248.7 kPa and at a boiling temperature of about 60°C.In some embodiments, the azeotropic composition consists essentially of about 38.1 weight percent dichloromethane and about 61.9 weight percent 1H,4H-octafluorobutane at a pressure of about 715 kPa and at a boiling temperature of about 100°C. In some embodiments, the azeotropic composition consists of about 38.1 weight percent dichloromethane and about 61.9 weight percent 1H,4H-octafluorobutane at a pressure of about 715 kPa and at a boiling temperature of about 100°C.In some embodiments, the azeotropic composition consists essentially of about 42.4 weight percent dichloromethane and about 57.6 weight percent 1H,4H-octafluorobutane at a pressure of about 101.3 kPa and at a boiling temperature of about 32.8°C. In some embodiments, the azeotropic composition consists of about 42.4 weight percent dichloromethane and about 57.6 weight percent 1H,4H-octafluorobutane at a pressure of about 101.3 kPa and at a boiling temperature of about 32.8°C.Azeotropic or azeotrope-like compositions comprising dichloromethane and 1-methoxynonafluorobutaneProvided herein are azeotropic or azeotrope-like compositions comprising dichloromethane and 1-methoxynonafluorobutane.In some embodiments, the azeotropic or azeotrope-like compositions comprise from about 38 to about 72 weight percent dichloromethane and from about 62 to about 28 weight percent 1-methoxynonafluorobutane, or from about 41 to about 66 weight percent dichloromethane and from about 59 to about 34 weight percent 1-methoxynonafluorobutane. These azeotropic or azeotrope-like compositions boil at a temperature of about 0 °C to about 100 °C and at a boiling pressure of about 21 kPa to about 698 kPa. In other embodiments, the azeotropic or azeotrope-like compositions comprise from about 43 to about 72 weight percent dichloromethane and from about 57 to about 28 weight percent 1-methoxynonafluorobutane, or from about 45 to about 66 weight percent dichloromethane and from about 55 to about 34 weight percent 1-methoxynonafluorobutane. These azeotropic or azeotrope-like compositions boil at a temperature of about 0 °C to about 60 °C and at a boiling pressure of about 21 kPa to about 232 kPa. In other embodiments, the azeotropic or azeotrope-like compositions comprise from about 46 to about 72 weight percent dichloromethane and from about 54 to about 28 weight percent 1-methoxynonafluorobutane, or from about 48 to about 66 weight percent dichloromethane and from about 52 to about 34 weight percent 1-methoxynonafluorobutane. These azeotropic or azeotrope-like compositions boil at a temperature of about 0 °C to about 40 °C and at a boiling pressure of about 21 kPa to about 120 kPa.In some embodiments, the azeotropic or azeotrope-like compositions consist essentially of from about 38 to about 72 weight percent dichloromethane and from about 62 to about 28 weight percent 1-methoxynonafluorobutane, or from about 41 to about 66 weight percent dichloromethane and from about 59 to about 34 weight percent 1-methoxynonafluorobutane. These azeotropic or azeotrope-like compositions boil at a temperature of about 0 °C to about 100 °C and at a boiling pressure of about 21 kPa to about 698 kPa. In other embodiments, the azeotropic or azeotrope-like compositions consist essentially of from about 43 to about 72 weight percent dichloromethane and from about 57 to about 28 weight percent 1-methoxynonafluorobutane, or from about 45 to about 66 weight percent dichloromethane and from about 55 to about 34 weight percent 1-methoxynonafluorobutane. These azeotropic or azeotrope-like compositions boil at a temperature of about 0 °C to about 60 °C and at a boiling pressure of about 21 kPa to about 232 kPa. In other embodiments, the azeotropic or azeotrope-like compositions consist essentially of from about 46 to about 72 weight percent dichloromethane and from about 54 to about 28 weight percent 1-methoxynonafluorobutane, or from about 48 to about 66 weight percent dichloromethane and from about 52 to about 34 weight percent 1-methoxynonafluorobutane. These azeotropic or azeotrope-like compositions boil at a temperature of about 0 °C to about 40 °C and at a boiling pressure of about 21 kPa to about 120 kPa.In some embodiments, the azeotropic or azeotrope-like compositions consist of from about 38 to about 72 weight percent dichloromethane and from about 62 to about 28 weight percent 1-methoxynonafluorobutane, or from about 41 to about 66 weight percent dichloromethane and from about 59 to about 34 weight percent 1-methoxynonafluorobutane. These azeotropic or azeotrope-like compositions boil at a temperature of about 0 °C to about 100 °C and at a boiling pressure of about 21 kPa to about 698 kPa. In other embodiments, the azeotropic or azeotrope-like compositions consist of from about 43 to about 72 weight percent dichloromethane and from about 57 to about 28 weight percent 1-methoxynonafluorobutane, or from about 45 to about 66 weight percent dichloromethane and from about 55 to about 34 weight percent 1-methoxynonafluorobutane. These azeotropic or azeotrope-like compositions boil at a temperature of about 0 °C to about 60 °C and at a boiling pressure of about 21 kPa to about 232 kPa. In other embodiments, the azeotropic or azeotrope-like compositions consist of from about 46 to about 72 weight percent dichloromethane and from about 54 to about 28 weight percent 1-methoxynonafluorobutane, or from about 48 to about 66 weight percent dichloromethane and from about 52 to about 34 weight percent 1-methoxynonafluorobutane. These azeotropic or azeotrope-like compositions boil at a temperature of about 0 °C to about 40 °C and at a boiling pressure of about 21 kPa to about 120 kPa.In some embodiments, the composition comprising dichloromethane and 1-methoxynonafluorobutane is azeotropic.In some embodiments, the azeotropic composition consists essentially of from about 50 to about 58 weight percent dichloromethane and from about 50 to about 42 weight percent 1-methoxynonafluorobutane. In some embodiments, the azeotropic composition consists of from about 50 to about 58 weight percent dichloromethane and from about 50 to about 42 weight percent 1-methoxynonafluorobutane. These azeotropic compositions boil at a temperature of about 0 °C to about 100 °C and at a boiling pressure of about 22 kPa to about 698 kPa.In some embodiments, the azeotropic composition consists essentially of about 58.0 weight percent dichloromethane and about 42.0 weight percent 1-methoxynonafluorobutane at a pressure of about 22.2 kPa and at a boiling temperature of about 0°C. In some embodiments, the azeotropic composition consists of about 58.0 weight percent dichloromethane and about 42.0 weight percent 1-methoxynonafluorobutane at a pressure of about 22.2 kPa and at a boiling temperature of about 0°C.In some embodiments, the azeotropic composition consists essentially of about 56.0 weight percent dichloromethane and about 44.0 weight percent 1-methoxynonafluorobutane at a pressure of about 55.3 kPa and at a boiling temperature of about 20°C. In some embodiments, the azeotropic composition consists of about 56.0 weight percent dichloromethane and about 44.0 weight percent 1-methoxynonafluorobutane at a pressure of about 55.3 kPa and at a boiling temperature of about 20°C.In some embodiments, the azeotropic composition consists essentially of about 54.0 weight percent dichloromethane and about 46.0 weight percent 1-methoxynonafluorobutane at a pressure of about 119.7 kPa and at a boiling temperature of about 40°C. In some embodiments, the azeotropic composition consists of about 54.0 weight percent dichloromethane and about 46.0 weight percent 1-methoxynonafluorobutane at a pressure of about 119.7 kPa and at a boiling temperature of about 40°C.In some embodiments, the azeotropic composition consists essentially of about 52.0 weight percent dichloromethane and about 48.0 weight percent 1-methoxynonafluorobutane at a pressure of about 232 kPa and at a boiling temperature of about 60°C. In some embodiments, the azeotropic composition consists of about 52.0 weight percent dichloromethane and about 48.0 weight percent 1-methoxynonafluorobutane at a pressure of about 232 kPa and at a boiling temperature of about 60°C.In some embodiments, the azeotropic composition consists essentially of about 50.0 weight percent dichloromethane and about 50.0 weight percent 1-methoxynonafluorobutane at a pressure of about 698 kPa and at a boiling temperature of about 100°C. In some embodiments, the azeotropic composition consists of about 50.0 weight percent dichloromethane and about 50.0 weight percent 1-methoxynonafluorobutane at a pressure of about 698 kPa and at a boiling temperature of about 100°C.In some embodiments, the azeotropic composition consists essentially of about 54.0 weight percent dichloromethane and about 46.0 weight percent 1-methoxynonafluorobutane at a pressure of about 101.3 kPa and at a boiling temperature of about 35.4°C. In some embodiments, the azeotropic composition consists of about 54.0 weight percent dichloromethane and about 46.0 weight percent 1-methoxynonafluorobutane at a pressure of about 101.3 kPa and at a boiling temperature of about 35.4°C.Azeotropic or azeotrope-like compositions comprising dichloromethane and 1-ethoxynonafluorobutaneProvided herein are azeotropic or azeotrope-like compositions comprising dichloromethane and 1-ethoxynonafluorobutane.In some embodiments, the azeotropic or azeotrope-like compositions comprise from about 54 to about 99 weight percent dichloromethane and from about 46 to about 1 weight percent 1-ethoxynonafluorobutane, or from about 57 to about 99 weight percent dichloromethane and from about 43 to about 1 weight percent 1-ethoxynonafluorobutane. These azeotropic or azeotrope-like compositions boil at a temperature of about -20 °C to about 100 °C and at a boiling pressure of about 6 kPa to about 604 kPa. In other embodiments, the azeotropic or azeotrope-like compositions comprise from about 61 to about 99 weight percent dichloromethane and from about 39 to about 1 weight percent 1-ethoxynonafluorobutane, or from about 64 to about 99 weight percent dichloromethane and from about 36 to about 1 weight percent 1-ethoxynonafluorobutane. These azeotropic or azeotrope-like compositions boil at a temperature of about -20 °C to about 60 °C and at a boiling pressure of about 6 kPa to about 205 kPa. In other embodiments, the azeotropic or azeotrope-like compositions comprise from about 65 to about 99 weight percent dichloromethane and from about 35 to about 1 weight percent 1-ethoxynonafluorobutane, or from about 67 to about 99 weight percent dichloromethane and from about 33 to about 1 weight percent 1-ethoxynonafluorobutane. These azeotropic or azeotrope-like compositions boil at a temperature of about -20 °C to about 40 °C and at a boiling pressure of about 6 kPa to about 106 kPa.In some embodiments, the azeotropic or azeotrope-like compositions consist essentially of from about 54 to about 99 weight percent dichloromethane and from about 46 to about 1 weight percent 1-ethoxynonafluorobutane, or from about 57 to about 99 weight percent dichloromethane and from about 43 to about 1 weight percent 1-ethoxynonafluorobutane. These azeotropic or azeotrope-like compositions boil at a temperature of about -20 °C to about 100 °C and at a boiling pressure of about 6 kPa to about 604 kPa. In other embodiments, the azeotropic or azeotrope-like compositions consist essentially of from about 61 to about 99 weight percent dichloromethane and from about 39 to about 1 weight percent 1-ethoxynonafluorobutane, or from about 64 to about 99 weight percent dichloromethane and from about 36 to about 1 weight percent 1-ethoxynonafluorobutane. These azeotropic or azeotrope-like compositions boil at a temperature of about -20 °C to about 60 °C and at a boiling pressure of about 6 kPa to about 205 kPa. In other embodiments, the azeotropic or azeotrope-like compositions consist essentially of from about 65 to about 99 weight percent dichloromethane and from about 35 to about 1 weight percent 1-ethoxynonafluorobutane, or from about 67 to about 99 weight percent dichloromethane and from about 33 to about 1 weight percent 1-ethoxynonafluorobutane. These azeotropic or azeotrope-like compositions boil at a temperature of about -20 °C to about 40 °C and at a boiling pressure of about 6 kPa to about 106 kPa.In some embodiments, the azeotropic or azeotrope-like compositions consist of from about 54 to about 99 weight percent dichloromethane and from about 46 to about 1 weight percent 1-ethoxynonafluorobutane, or from about 57 to about 99 weight percent dichloromethane and from about 43 to about 1 weight percent 1-ethoxynonafluorobutane. These azeotropic or azeotrope-like compositions boil at a temperature of about -20 °C to about 100 °C and at a boiling pressure of about 6 kPa to about 604 kPa. In other embodiments, the azeotropic or azeotrope-like compositions consist of from about 61 to about 99 weight percent dichloromethane and from about 39 to about 1 weight percent 1-ethoxynonafluorobutane, or from about 64 to about 99 weight percent dichloromethane and from about 36 to about 1 weight percent 1-ethoxynonafluorobutane. These azeotropic or azeotrope-like compositions boil at a temperature of about -20 °C to about 60 °C and at a boiling pressure of about 6 kPa to about 205 kPa. In other embodiments, the azeotropic or azeotrope-like compositions consist of from about 65 to about 99 weight percent dichloromethane and from about 35 to about 1 weight percent 1-ethoxynonafluorobutane, or from about 67 to about 99 weight percent dichloromethane and from about 33 to about 1 weight percent 1-ethoxynonafluorobutane. These azeotropic or azeotrope-like compositions boil at a temperature of about -20 °C to about 40 °C and at a boiling pressure of about 6 kPa to about 106 kPa.In some embodiments, the composition comprising dichloromethane and 1-ethoxynonafluorobutane is azeotropic.In some embodiments, the azeotropic composition consists essentially of from about 67 to about 84 weight percent dichloromethane and from about 33 to about 16 weight percent 1-ethoxynonafluorobutane. In some embodiments, the azeotropic composition consists of from about 67 to about 84 weight percent dichloromethane and from about 33 to about 16 weight percent 1-ethoxynonafluorobutane. These azeotropic compositions boil at a temperature of about -20 °C to about 100 °C and at a boiling pressure of about 6 kPa to about 604 kPa.In some embodiments, the azeotropic composition consists essentially of about 84.0 weight percent dichloromethane and about 16.0 weight percent 1-ethoxynonafluorobutane at a pressure of about 6.6 kPa and at a boiling temperature of about -20°C. In some embodiments, the azeotropic composition consists of about 84.0 weight percent dichloromethane and about 16.0 weight percent 1-ethoxynonafluorobutane at a pressure of about 6.6 kPa and at a boiling temperature of about -20°C.In some embodiments, the azeotropic composition consists essentially of about 79.0 weight percent dichloromethane and about 21.0 weight percent 1-ethoxynonafluorobutane at a pressure of about 48.9 kPa and at a boiling temperature of about 20°C. In some embodiments, the azeotropic composition consists of about 79.0 weight percent dichloromethane and about 21.0 weight percent 1-ethoxynonafluorobutane at a pressure of about 48.9 kPa and at a boiling temperature of about 20°C.In some embodiments, the azeotropic composition consists essentially of about 76.0 weight percent dichloromethane and about 24.0 weight percent 1-ethoxynonafluorobutane at a pressure of about 105.7 kPa and at a boiling temperature of about 40°C. In some embodiments, the azeotropic composition consists of about 76.0 weight percent dichloromethane and about 24.0 weight percent 1-ethoxynonafluorobutane at a pressure of about 105.7 kPa and at a boiling temperature of about 40°C.In some embodiments, the azeotropic composition consists essentially of about 73.0 weight percent dichloromethane and about 27.0 weight percent 1-ethoxynonafluorobutane at a pressure of about 205 kPa and at a boiling temperature of about 60°C. In some embodiments, the azeotropic composition consists of about 73.0 weight percent dichloromethane and about 27.0 weight percent 1-ethoxynonafluorobutane at a pressure of about 205 kPa and at a boiling temperature of about 60°C.In some embodiments, the azeotropic composition consists essentially of about 66.9 weight percent dichloromethane and about 33.1 weight percent 1-ethoxynonafluorobutane at a pressure of about 604 kPa and at a boiling temperature of about 100°C. In some embodiments, the azeotropic composition consists of about 66.9 weight percent dichloromethane and about 33.1 weight percent 1-ethoxynonafluorobutane at a pressure of about 604 kPa and at a boiling temperature of about 100°C.In some embodiments, the azeotropic composition consists essentially of about 76.0 weight percent dichloromethane and about 24.0 weight percent 1-ethoxynonafluorobutane at a pressure of about 101.3 kPa and at a boiling temperature of about 38.8°C. In some embodiments, the azeotropic composition consists of about 76.0 weight percent dichloromethane and about 24.0 weight percent 1-ethoxynonafluorobutane at a pressure of about 101.3 kPa and at a boiling temperature of about 38.8°C.Properties of the azeotropic or azeotrope-like compositionsThe compound dichloromethane (DCM) has a reported GWP-100 of 11.2 (IPCC 2021 report). The compound 1H,4H-octafluorobutane (HFC-338pcc) has a reported GWP-100 of 1119 (J. B. Burkholder et al. J. Phys. Chem. A 2020, 124, 4793-4800). The compound 1-methoxynonafluorobutane (HFC-449mcc or HFE-449s1 or HFE-7100) has a reported GWP-100 of 460 (IPCC 2021 report) and the compound 1-ethoxynonafluorobutane (HFC-569mcc or HFE-569sf2 or HFE-7200) has a reported GWP-100 of 60.7 (IPCC 2021 report).Accordingly, the azeotropic or azeotrope-like compositions combining the two compounds dichloromethane and 1H,4H-octafluorobutane or the two compounds dichloromethane and 1-methoxynonafluorobutane or the two compounds dichloromethane and 1-ethoxynonafluorobutane have a low global warming potential (GWP). In some embodiments, the azeotropic or azeotrope-like compositions comprising dichloromethane and 1H,4H-octafluorobutane have a GWP-100 (global warming potential over a 100-year period) of less than about 790, in other embodiments of less than about 655, in other embodiments of less than about 545, and in other embodiments of less than about 390. In some embodiments the azeotropic or azeotrope-like compositions comprising dichloromethane and 1-methoxynonafluorobutane have a GWP-100 (global warming potential over a 100-year period) of less than about 290, in other embodiments of less than about 255, in other embodiments of less than about 220, and in other embodiments of less than about 165. In some embodiments the azeotropic or azeotrope-like compositions comprising dichloromethane and 1-ethoxynonafluorobutane have a GWP-100 (global warming potential over a 100-year period) of less than about 34, in other embodiments of less than about 31, in other embodiments of less than about 23, and in other embodiments of less than about 20.The azeotropic or azeotrope-like compositions as described herein have the advantage of being homogeneous azeotropic or azeotrope-like compositions. For homogenous azeotropic or azeotrope-like compositions, the components of the composition at ambient temperatures and pressures form a single liquid phase. This is to be contrasted with heterogeneous azeotropic or azeotrope-like compositions, where, due to low miscibility of the components of the composition, the components of the composition undergo phase separation in the liquid phase. Phase separation is usually undesired since processes involving the composition are more complex and expensive. The homogeneous nature of the azeotropic or azeotrope-like compositions is achievable over a broad range of practical conditions including ambient pressure and temperature.The azeotropic or azeotrope-like compositions are useful in a wide range of applications. In some embodiments, the azeotropic or azeotrope-like compositions are used as spin agents for flash spinning, in other embodiments as cleaning agents, and in other embodiments as solvents.Spin Agents and Spin Fluids for Flash SpinningIn some embodiments, the azeotropic or azeotrope-like compositions are spin agents within spin fluids for flash spinning.In some embodiments, the spin fluid comprises (a) from about 6 to about 24 weight percent of a polyolefin, based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises or consists essentially of the azeotropic or azeotrope-like composition comprising dichloromethane and 1H,4H-octafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-methoxynonafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-ethoxynonafluorobutane. In other embodiments, the spin fluid comprises (a) from about 6 to about 20 weight percent of a polyolefin, based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises or consists essentially of the azeotropic or azeotrope-like composition comprising dichloromethane and 1H,4H-octafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-methoxynonafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-ethoxynonafluorobutane. In other embodiments, the spin fluid comprises (a) from about 8 to about 20 weight percent of a polyolefin, based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises or consists essentially of the azeotropic or azeotrope-like composition comprising dichloromethane and 1H,4H-octafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-methoxynonafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-ethoxynonafluorobutane. In other embodiments, the spin fluid comprises (a) from about 8 to about 16 weight percent of a polyolefin, based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises or consists essentially of the azeotropic or azeotrope-like composition comprising dichloromethane and 1H,4H-octafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-methoxynonafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-ethoxynonafluorobutane. In other embodiments, the spin fluid comprises (a) from about 8 to about 14 weight percent of a polyolefin, based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises or consists essentially of the azeotropic or azeotrope-like composition comprising dichloromethane and 1H,4H-octafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-methoxynonafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-ethoxynonafluorobutane.In some embodiments, the spin fluid comprises (a) from about 6 to about 24 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1, or a poly(4-methyl-1-pentene), based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises or consists essentially of the azeotropic or azeotrope-like composition comprising dichloromethane and 1H,4H-octafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-methoxynonafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-ethoxynonafluorobutane. In other embodiments, the spin fluid comprises (a) from about 6 to about 20 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1, or a poly(4-methyl-1-pentene), based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises or consists essentially of the azeotropic or azeotrope-like composition comprising dichloromethane and 1H,4H-octafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-methoxynonafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-ethoxynonafluorobutane. In other embodiments, the spin fluid comprises (a) from about 8 to about 20 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1, or a poly(4-methyl-1-pentene), based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises or consists essentially of the azeotropic or azeotrope-like composition comprising dichloromethane and 1H,4H-octafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-methoxynonafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-ethoxynonafluorobutane. In other embodiments, the spin fluid comprises (a) from about 8 to about 16 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1, or a poly(4-methyl-1-pentene), based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises or consists essentially of the azeotropic or azeotrope-like composition comprising dichloromethane and 1H,4H-octafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-methoxynonafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-ethoxynonafluorobutane. In other embodiments, the spin fluid comprises (a) from about 8 to about 14 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1, or a poly(4-methyl-1-pentene), based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises or consists essentially of the azeotropic or azeotrope-like composition comprising dichloromethane and 1H,4H-octafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-methoxynonafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-ethoxynonafluorobutane.In some embodiments, the spin fluid comprises from about 76 to about 94 weight percent of a spin agent, based on the total amount of the spin fluid. In some embodiments, the spin fluid comprises from about 80 to about 94 weight percent of a spin agent, based on the total amount of the spin fluid, in other embodiments from about 80 to about 92 weight percent, based on the total amount of the spin fluid, in other embodiments from about 84 to about 92 weight percent, based on the total amount of the spin fluid, and in other embodiments from about 86 to about 92 weight percent, based on the total amount of the spin fluid.In some embodiments, the spin agent consists essentially of from about 32 to about 62 weight percent dichloromethane and from about 68 to about 38 weight percent 1H,4H-octafluorobutane, in other embodiments from about 35 to about 58 weight percent dichloromethane and from about 65 to about 42 weight percent 1H,4H-octafluorobutane. In some embodiments, the spin agent consists essentially of from about 40 to about 61 weight percent dichloromethane and from about 60 to about 39 weight percent 1H,4H-octafluorobutane, in other embodiments from about 52 to about 60 weight percent dichloromethane and from about 48 to about 40 weight percent 1H,4H-octafluorobutane, and in other embodiments from about 48 to about 62 weight percent dichloromethane and from about 52 to about 38 weight percent 1H,4H-octafluorobutane.In some embodiments, the spin agent consists essentially of from about 46 to about 70 weight percent dichloromethane and from about 54 to about 30 weight percent 1-methoxynonafluorobutane. In some embodiments, the spin agent consists essentially of from about 48 to about 65 weight percent dichloromethane and from about 52 to about 35 weight percent 1-methoxynonafluorobutane, and in other embodiments from about 50 to about 65 weight percent dichloromethane and from about 50 to about 35 weight percent 1-methoxynonafluorobutane.In some embodiments, the spin agent consists essentially of from about 70 to about 85 weight percent dichloromethane and from about 30 to about 15 weight percent 1-ethoxynonafluorobutane. In some embodiments, the spin agent consists essentially of from about 75 to about 85 weight percent dichloromethane and from about 25 to about 15 weight percent 1-ethoxynonafluorobutane, and in other embodiments from about 75 to about 80 weight percent dichloromethane and from about 25 to about 20 weight percent 1-ethoxynonafluorobutane. In some embodiments, the spin agent consists essentially of from about 66 to about 70 weight percent dichloromethane and from about 34 to about 30 weight percent 1-ethoxynonafluorobutane.The spin fluid may include additives, such as antioxidants or acid scavengers in minor amounts, provided that their presence does not interfere with the azeotropic or azeotrope-like nature of the compositions of dichloromethane and 1H,4H-octafluorobutane, or dichloromethane and 1-methoxynonafluorobutane, or dichloromethane and 1-ethoxynonafluorobutane described herein. In some embodiments, the spin fluid comprises additives in an amount of about 1.5 weight percent or less of the total amount of the spin agent, and in other embodiments in an amount of about 0.1 weight percent or less of the total amount of the spin agent.In some embodiments, the spin agent consists of from about 32 to about 62 weight percent dichloromethane and from about 68 to about 38 weight percent 1H,4H-octafluorobutane, in other embodiments from about 35 to about 58 weight percent dichloromethane and from about 65 to about 42 weight percent 1H,4H-octafluorobutane. In some embodiments, the spin agent consists of from about 40 to about 61 weight percent dichloromethane and from about 60 to about 39 weight percent 1H,4H-octafluorobutane, in other embodiments from about 52 to about 60 weight percent dichloromethane and from about 48 to about 40 weight percent 1H,4H-octafluorobutane, and in other embodiments from about 48 to about 62 weight percent dichloromethane and from about 52 to about 38 weight percent 1H,4H-octafluorobutane.In some embodiments, the spin agent consists of from about 46 to about 70 weight percent dichloromethane and from about 54 to about 30 weight percent 1-methoxynonafluorobutane. In some embodiments, the spin agent consists of from about 48 to about 65 weight percent dichloromethane and from about 52 to about 35 weight percent 1-methoxynonafluorobutane, and in other embodiments from about 50 to about 65 weight percent dichloromethane and from about 50 to about 35 weight percent 1-methoxynonafluorobutane.In some embodiments, the spin agent consists of from about 70 to about 85 weight percent dichloromethane and from about 30 to about 15 weight percent 1-ethoxynonafluorobutane. In some embodiments, the spin agent consists of from about 75 to about 85 weight percent dichloromethane and from about 25 to about 15 weight percent 1-ethoxynonafluorobutane, and in other embodiments from about 75 to about 80 weight percent dichloromethane and from about 25 to about 20 weight percent 1-ethoxynonafluorobutane. In some embodiments, the spin agent consists of from about 66 to about 70 weight percent dichloromethane and from about 34 to about 30 weight percent 1-ethoxynonafluorobutane.The spin agent can be used for a broad range of different polyolefins and blends / mixtures thereof.In some embodiments, polyolefins are polyethylene (PE), polypropylene (PP), polybutene-1 (PB-1), poly(4-methyl-1-pentene) (P4M1P), and blends / mixtures thereof. In other embodiments, the polyolefins are blends comprising polyethylene, blends comprising polypropylene, blends comprising polybutene-1, or blends comprising poly(4-methyl-1-pentene). Particularly preferred polyolefins are polyethylene (PE), in particular high-density polyethylene (HDPE), and blends / mixtures of high-density polyethylene (HDPE) and low-density polyethylene (LDPE), in particular linear low-density polyethylene (LLDPE). In some embodiments, the polyolefin is a high-density polyethylene (HDPE).In some embodiments, the spin fluid comprises about 6 to about 24 weight percent, or about 6 to about 20 weight percent, or about 8 to about 20 weight percent, or about 8 to about 16 weight percent, or about 8 to about 14 weight percent of a polypropylene, a polybutene-1, or a poly(4-methyl-1-pentene), based on the total amount of the spin fluid, and a spin agent, wherein the spin agent consists essentially of or consists of from about 32 to about 62 weight percent dichloromethane and from about 68 to about 38 weight percent 1H,4H-octafluorobutane, or from about 35 to about 58 weight percent dichloromethane and from about 65 to about 42 weight percent 1H,4H-octafluorobutane, or from about 40 to about 61 weight percent dichloromethane and from about 60 to about 39 weight percent 1H,4H-octafluorobutane, or from about 52 to about 60 weight percent dichloromethane and from about 48 to about 40 weight percent 1H,4H-octafluorobutane, or from about 48 to about 62 weight percent dichloromethane and from about 52 to about 38 weight percent 1H,4H-octafluorobutane.In some embodiments, the spin fluid comprises about 6 to about 24 weight percent, or about 6 to about 20 weight percent, or about 8 to about 20 weight percent, or about 8 to about 16 weight percent, or about 8 to about 14 weight percent of a polypropylene, a polybutene-1, or a poly(4-methyl-1-pentene), based on the total amount of the spin fluid, and a spin agent, wherein the spin agent consists essentially of or consists of from about 46 to about 70 weight percent dichloromethane and from about 54 to about 30 weight percent 1-methoxynonafluorobutane, or from about 48 to about 65 weight percent dichloromethane and from about 52 to about 35 weight percent 1-methoxynonafluorobutane, or from about 50 to about 65 weight percent dichloromethane and from about 50 to about 35 weight percent 1-methoxynonafluorobutane.In some embodiments, the spin fluid comprises about 6 to about 24 weight percent, or about 6 to about 20 weight percent, or about 8 to about 20 weight percent, or about 8 to about 16 weight percent, or about 8 to about 14 weight percent of a polyethylene, based on the total amount of the spin fluid, and a spin agent, wherein the spin agent consists essentially of or consists of from about 70 to about 85 weight percent dichloromethane and from about 30 to about 15 weight percent 1-ethoxynonafluorobutane, or from about 75 to about 85 weight percent dichloromethane and from about 25 to about 15 weight percent 1-ethoxynonafluorobutane, or from about 75 to about 80 weight percent dichloromethane and from about 25 to about 20 weight percent 1-ethoxynonafluorobutane.In some embodiments, the spin fluid comprises about 6 to about 24 weight percent, or about 6 to about 20 weight percent, or about 8 to about 20 weight percent, or about 8 to about 16 weight percent, or about 8 to about 14 weight percent of a polypropylene, a polybutene-1, or a poly(4-methyl-1-pentene), based on the total amount of the spin fluid, and a spin agent, wherein the spin agent consists essentially of or consists of from about 66 to about 70 weight percent dichloromethane and from about 34 to about 30 weight percent 1-ethoxynonafluorobutane.In some embodiments, the spin fluid comprising the azeotropic or azeotrope-like composition as described herein exhibits a cloud point pressure of about 45 to about 300 bar, in other embodiments of about 50 to about 300 bar, and in other embodiments of about 70 to about 300 bar. In some embodiments, the spin fluid comprising the azeotropic or azeotrope-like composition as described herein exhibits a cloud point pressure of about 45 to about 250 bar, in other embodiments of about 50 to about 250 bar, and in other embodiments of about 70 to about 250 bar. In some embodiments, the spin fluid comprising the azeotropic or azeotrope-like composition as described herein exhibits a cloud point pressure of about 45 to about 200 bar, in other embodiments of about 50 to about 200 bar, and in other embodiments of about 70 to about 200 bar. The flash spinning process must take place at an operating pressure below the spin fluid's cloud point pressure but above the spin fluid's bubble point pressure. If the cloud point pressure is above about 300 bar, the flash spinning equipment must be built to withstand very high pressure which increases costs and operational constraints.When used as a spin agent, the homogeneous azeotropic or azeotrope-like compositions have the advantage that in the spin agent recovery process, upon condensation of the spin agent, no phase separation occurs. Furthermore, the azeotropic or azeotrope-like compositions described herein result in spin fluids with a cloud point pressures at or close to the azeotrope. This makes it easier to condense the used spin agent into a liquid with the same or substantially the same composition so that it can be re-used.Preparation of Plexifilamentary Film-fibril Strands of PolyolefinIn some embodiments, there is provided a process for the preparation of plexifilamentary fibrils of polyolefin. The process comprises the steps of:(i) generating a spin fluid comprising(a) about 6 to about 24 weight percent of a polyolefin, based on the total amount of the spin fluid, and(b) a spin agent, and(ii) flash spinning the spin fluid at a pressure above the vapor pressure of the spin fluid into a region of essentially atmospheric pressure to form plexifilamentary fibrils of the polyolefin;wherein the spin agent comprises or consists essentially of(1) an azeotropic or azeotrope-like composition comprising dichloromethane and 1H,4H-octafluorobutane,(2) an azeotropic or azeotrope-like composition comprising dichloromethane and 1-methoxynonafluorobutane, or(3) an azeotropic or azeotrope-like composition comprising dichloromethane and 1-ethoxynonafluorobutane.In some embodiments, the flash-spinning is performed at a pressure of about 45 to about 300 bar, or of about 50 to about 300 bar, or of about 70 to about 300 bar. In some embodiments, the flash-spinning is performed at a pressure of about 45 to about 250 bar, in other embodiments of about 50 to about 250 bar, and in other embodiments of about 70 to about 250 bar. In some embodiments, the flash-spinning is performed at a pressure of about 45 to about 200 bar, in other embodiments of about 50 to about 200 bar, and in other embodiments of about 70 to about 200 bar. The region of lower pressure into which flash spinning occurs is usually at or around atmospheric pressure.In some embodiments, the spin fluid comprises (a) from about 6 to about 20 weight percent of a polyolefin, based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises or consists essentially of the azeotropic or azeotrope-like composition comprising dichloromethane and 1H,4H-octafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-methoxynonafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-ethoxynonafluorobutane. In other embodiments, the spin fluid comprises (a) from about 8 to about 20 weight percent of a polyolefin, based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises or consists essentially of the azeotropic or azeotrope-like composition comprising dichloromethane and 1H,4H-octafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-methoxynonafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-ethoxynonafluorobutane. In other embodiments, the spin fluid comprises (a) from about 8 to about 16 weight percent of a polyolefin, based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises or consists essentially of the azeotropic or azeotrope-like composition comprising dichloromethane and 1H,4H-octafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-methoxynonafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-ethoxynonafluorobutane. In other embodiments, the spin fluid comprises (a) from about 8 to about 14 weight percent of a polyolefin, based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises or consists essentially of the azeotropic or azeotrope-like composition comprising dichloromethane and 1H,4H-octafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-methoxynonafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-ethoxynonafluorobutane.In some embodiments, the spin fluid comprises (a) from about 6 to about 24 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1, or a poly(4-methyl-1-pentene), based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises or consists essentially of the azeotropic or azeotrope-like composition comprising dichloromethane and 1H,4H-octafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-methoxynonafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-ethoxynonafluorobutane. In other embodiments, the spin fluid comprises (a) from about 6 to about 20 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1, or a poly(4-methyl-1-pentene), based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises or consists essentially of the azeotropic or azeotrope-like composition comprising dichloromethane and 1H,4H-octafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-methoxynonafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-ethoxynonafluorobutane. In other embodiments, the spin fluid comprises (a) from about 8 to about 20 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1, or a poly(4-methyl-1-pentene), based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises or consists essentially of the azeotropic or azeotrope-like composition comprising dichloromethane and 1H,4H-octafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-methoxynonafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-ethoxynonafluorobutane. In other embodiments, the spin fluid comprises (a) from about 8 to about 16 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1, or a poly(4-methyl-1-pentene), based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises or consists essentially of the azeotropic or azeotrope-like composition comprising dichloromethane and 1H,4H-octafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-methoxynonafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-ethoxynonafluorobutane. In other embodiments, the spin fluid comprises (a) from about 8 to about 14 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1, or a poly(4-methyl-1-pentene), based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises or consists essentially of the azeotropic or azeotrope-like composition comprising dichloromethane and 1H,4H-octafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-methoxynonafluorobutane, or the azeotropic or azeotrope-like composition comprising dichloromethane and 1-ethoxynonafluorobutane.In some embodiments, the spin fluid comprises from about 76 to about 94 weight percent of a spin agent, based on the total amount of the spin fluid. In some embodiments, the spin fluid comprises from about 80 to about 94 weight percent of a spin agent, based on the total amount of the spin fluid, in other embodiments from about 80 to about 92 weight percent, based on the total amount of the spin fluid, in other embodiments from about 84 to about 92 weight percent, based on the total amount of the spin fluid, and in other embodiments from about 86 to about 92 weight percent, based on the total amount of the spin fluid.In some embodiments, the spin agent consists essentially of from about 32 to about 62 weight percent dichloromethane and from about 68 to about 38 weight percent 1H,4H-octafluorobutane, in other embodiments from about 35 to about 58 weight percent dichloromethane and from about 65 to about 42 weight percent 1H,4H-octafluorobutane. In some embodiments, the spin agent consists essentially of from about 40 to about 61 weight percent dichloromethane and from about 60 to about 39 weight percent 1H,4H-octafluorobutane, in other embodiments from about 52 to about 60 weight percent dichloromethane and from about 48 to about 40 weight percent 1H,4H-octafluorobutane, and in other embodiments from about 48 to about 62 weight percent dichloromethane and from about 52 to about 38 weight percent 1H,4H-octafluorobutane.In some embodiments, the spin agent consists essentially of from about 46 to about 70 weight percent dichloromethane and from about 54 to about 30 weight percent 1-methoxynonafluorobutane. In some embodiments, the spin agent consists essentially of from about 48 to about 65 weight percent dichloromethane and from about 52 to about 35 weight percent 1-methoxynonafluorobutane, and in other embodiments from about 50 to about 65 weight percent dichloromethane and from about 50 to about 35 weight percent 1-methoxynonafluorobutane.In some embodiments, the spin agent consists essentially of from about 70 to about 85 weight percent dichloromethane and from about 30 to about 15 weight percent 1-ethoxynonafluorobutane. In some embodiments, the spin agent consists essentially of from about 75 to about 85 weight percent dichloromethane and from about 25 to about 15 weight percent 1-ethoxynonafluorobutane, and in other embodiments from about 75 to about 80 weight percent dichloromethane and from about 25 to about 20 weight percent 1-ethoxynonafluorobutane. In some embodiments, the spin agent consists essentially of from about 66 to about 70 weight percent dichloromethane and from about 34 to about 30 weight percent 1-ethoxynonafluorobutane.The spin fluid may include additives, such as antioxidants or acid scavengers in minor amounts, provided that their presence does not interfere with the azeotropic or azeotrope-like nature of the compositions of dichloromethane and 1H,4H-octafluorobutane, or dichloromethane and 1-methoxynonafluorobutane, or dichloromethane and 1-ethoxynonafluorobutane described herein. In some embodiments, the spin fluid comprises additives in an amount of about 1.5 weight percent or less of the total amount of the spin agent, and in other embodiments in an amount of about 0.1 weight percent or less of the total amount of the spin agent.In some embodiments, the spin agent consists of from about 32 to about 62 weight percent dichloromethane and from about 68 to about 38 weight percent 1H,4H-octafluorobutane, in other embodiments from about 35 to about 58 weight percent dichloromethane and from about 65 to about 42 weight percent 1H,4H-octafluorobutane. In some embodiments, the spin agent consists of from about 40 to about 61 weight percent dichloromethane and from about 60 to about 39 weight percent 1H,4H-octafluorobutane, in other embodiments from about 52 to about 60 weight percent dichloromethane and from about 48 to about 40 weight percent 1H,4H-octafluorobutane, and in other embodiments from about 48 to about 62 weight percent dichloromethane and from about 52 to about 38 weight percent 1H,4H-octafluorobutane.In some embodiments, the spin agent consists of from about 46 to about 70 weight percent dichloromethane and from about 54 to about 30 weight percent 1-methoxynonafluorobutane. In some embodiments, the spin agent consists of from about 48 to about 65 weight percent dichloromethane and from about 52 to about 35 weight percent 1-methoxynonafluorobutane, and in other embodiments from about 50 to about 65 weight percent dichloromethane and from about 50 to about 35 weight percent 1-methoxynonafluorobutane.In some embodiments, the spin agent consists of from about 70 to about 85 weight percent dichloromethane and from about 30 to about 15 weight percent 1-ethoxynonafluorobutane. In some embodiments, the spin agent consists of from about 75 to about 85 weight percent dichloromethane and from about 25 to about 15 weight percent 1-ethoxynonafluorobutane, and in other embodiments from about 75 to about 80 weight percent dichloromethane and from about 25 to about 20 weight percent 1-ethoxynonafluorobutane. In some embodiments, the spin agent consists of from about 66 to about 70 weight percent dichloromethane and from about 34 to about 30 weight percent 1-ethoxynonafluorobutane.The spin agent can be used for a broad range of different polyolefins and blends / mixtures thereof.In some embodiments, polyolefins are polyethylene (PE), polypropylene (PP), polybutene-1 (PB-1), poly(4-methyl-1-pentene) (P4M1P), and blends / mixtures thereof. In other embodiments, the polyolefins are blends comprising polyethylene, blends comprising polypropylene, blends comprising polybutene-1, or blends comprising poly(4-methyl-1-pentene). Particularly preferred polyolefins are polyethylene (PE), in particular high-density polyethylene (HDPE), and blends / mixtures of high-density polyethylene (HDPE) and low-density polyethylene (LDPE), in particular linear low-density polyethylene (LLDPE). In some embodiments, the polyolefin is a high-density polyethylene (HDPE).In some embodiments, the spin fluid comprises about 6 to about 24 weight percent, or about 6 to about 20 weight percent, or about 8 to about 20 weight percent, or about 8 to about 16 weight percent, or about 8 to about 14 weight percent of a polypropylene, a polybutene-1, or a poly(4-methyl-1-pentene), based on the total amount of the spin fluid, and a spin agent, wherein the spin agent consists essentially of or consists of from about 32 to about 62 weight percent dichloromethane and from about 68 to about 38 weight percent 1H,4H-octafluorobutane, or from about 35 to about 58 weight percent dichloromethane and from about 65 to about 42 weight percent 1H,4H-octafluorobutane, or from about 40 to about 61 weight percent dichloromethane and from about 60 to about 39 weight percent 1H,4H-octafluorobutane, or from about 52 to about 60 weight percent dichloromethane and from about 48 to about 40 weight percent 1H,4H-octafluorobutane, or from about 48 to about 62 weight percent dichloromethane and from about 52 to about 38 weight percent 1H,4H-octafluorobutane.In some embodiments, the spin fluid comprises about 6 to about 24 weight percent, or about 6 to about 20 weight percent, or about 8 to about 20 weight percent, or about 8 to about 16 weight percent, or about 8 to about 14 weight percent of a polypropylene, a polybutene-1, or a poly(4-methyl-1-pentene), based on the total amount of the spin fluid, and a spin agent, wherein the spin agent consists essentially of or consists of from about 46 to about 70 weight percent dichloromethane and from about 54 to about 30 weight percent 1-methoxynonafluorobutane, or from about 48 to about 65 weight percent dichloromethane and from about 52 to about 35 weight percent 1-methoxynonafluorobutane, or from about 50 to about 65 weight percent dichloromethane and from about 50 to about 35 weight percent 1-methoxynonafluorobutane.In some embodiments, the spin fluid comprises about 6 to about 24 weight percent, or about 6 to about 20 weight percent, or about 8 to about 20 weight percent, or about 8 to about 16 weight percent, or about 8 to about 14 weight percent of a polyethylene, based on the total amount of the spin fluid, and a spin agent, wherein the spin agent consists essentially of or consists of from about 70 to about 85 weight percent dichloromethane and from about 30 to about 15 weight percent 1-ethoxynonafluorobutane, or from about 75 to about 85 weight percent dichloromethane and from about 25 to about 15 weight percent 1-ethoxynonafluorobutane, or from about 75 to about 80 weight percent dichloromethane and from about 25 to about 20 weight percent 1-ethoxynonafluorobutane.In some embodiments, the spin fluid comprises about 6 to about 24 weight percent, or about 6 to about 20 weight percent, or about 8 to about 20 weight percent, or about 8 to about 16 weight percent, or about 8 to about 14 weight percent of a polypropylene, a polybutene-1, or a poly(4-methyl-1-pentene), based on the total amount of the spin fluid, and a spin agent, wherein the spin agent consists essentially of or consists of from about 66 to about 70 weight percent dichloromethane and from about 34 to about 30 weight percent 1-ethoxynonafluorobutane.In some embodiments, there is provided plexifilamentary fibrils of polyolefin obtainable by the process described herein.The shape of the assembly of plexifilamentary fibrils of polyolefin discharged from each spin orifice may be modified by any methods known in the art. In some embodiments, the plexifilamentary fibrils of polyolefin discharged from each spin orifice may be modified by passing into a shroud such as described on US 3,387,326, in other embodiments by passing into a slotted outlet such as described in US 3,467,744 or US 5,788,993, and in other embodiments passing into a slot fan jet as described in US 8,114,325. In some embodiments, streams of fibrils from multiple orifices may exit via a common slot as described in US 3,564,088.Preparation of Sheets of Nonwoven Flash-spun Plexifilamentary Fibrils by Collection, Consolidation, Bonding, Softening, and Articles Made from Sheets of Nonwoven Flash-spun Plexifilamentary FibrilsSheets comprising plexifilamentary fibrils of polyolefin can be formed by any method known in the art. In some embodiments, the stream of fibrils discharged from each spin orifice is directed towards a deflector device which alternately directs the stream of fibrils to the left and right onto a moving collecting device such that the fibrils accumulate in the form of a collected sheet of nonwoven flash-spun plexifilamentary fibrils, formed from fibrils oriented in an overlapping, multi-directional configuration. Deflection of the stream of fibrils may be achieved by any suitable means known in the art, including, but not limited to, those described in US 3,277,526 and US 3,387,326, US 3,169,899, US 3,497,918, US 3,456,156, US 3,593,074, US 3,851,023 and US 3,860,369, US 4,148,595, US 5,045,258, US 5,643,524, US 5,731,011, US 5,750,152 and WO92 / 20511. The stream of fibrils may also be laid down to form a collected sheet of nonwoven flash-spun plexifilamentary fibrils without deflection as described in US 5,788,993 and US 8,114,325. The method of forming a collected sheet of nonwoven flash-spun plexifilamentary fibrils may further utilize structures in the spin cell such as those described in US 5,123,983, US 5,296,172, and WO92 / 20511.In some embodiments, the streams of fibrils are discharged from spin orifices located on a rotating support, and the fibrils are collected on a collecting belt which surrounds the rotating arrangement circumferentially as described in US 7,118,698, US 7,621,731, US 7,786,034, and US 7,998,388.In some embodiments, the collected sheet of nonwoven flash-spun plexifilamentary fibrils formed by flash-spinning as described herein may be consolidated by applying a small amount of pressure to the sheet to form a consolidated sheet of nonwoven flash-spun plexifilamentary fibrils. In some embodiments, the sheet may be passed under a roller which applies pressure to the sheet to form a consolidated sheet.In some embodiments, a consolidated sheet as described herein is subjected to thermal or mechanical bonding as known in the art to form a thermally or mechanically bonded sheet. Bonding may also be achieved by impregnation of a consolidated sheet with a chemical bonding agent, either throughout the entire sheet, or at isolated points distributed over the sheet, or pattern-wise.In some embodiments, the bonded sheet is subjected to a mechanical softening process to obtain a softened sheet of nonwoven flash-spun plexifilamentary fibrils.In some embodiments, an antistatic treatment is applied to the bonded or softened sheet. In some embodiments, the antistatic treatment is applied by applying a coating composition comprising an antistatic compound.Further embodiments relate to a multilayer structure comprising at least one sheet of nonwoven flash-spun plexifilamentary fibrils as described herein, and at least one further sheet or a film. In some embodiments, the sheet of nonwoven flash-spun plexifilamentary fibrils as described herein is a collected sheet, a consolidated sheet, a bonded sheet or a softened sheet.The sheet of nonwoven flash-spun plexifilamentary fibrils as described herein has many uses and may be used in a variety of articles and applications, including, but not limited to, multilayer structures, garments (including, but not limited to, protective apparel), house wrap, roof lining, car covers, medical and non-medical packaging, filtration media, print media, tags and labels, and accessories.EXAMPLESA study has been performed for the phase behavior and flash spinning of polyethylene, ethylene-hexene copolymer, polypropylene, polybutene-1, and a poly(4-methyl-1-pentene) for azeotropic and azeotrope-like compositions. The experimental procedure and results are provided below. These examples are given to illustrate exemplary embodiments of the invention and should not be interpreted as limiting in any way.Materials UsedDichloromethane (DCM), CAS No. 75-09-2 has an atmospheric boiling point of 39.6 °C and a molecular weight of 84.93 g / mol. The dichloromethane used had a purity level above 99.5 percent by weight.1H,4H-octafluorobutane (HFC-338pcc), CAS No. 377-36-6, has an atmospheric boiling point of 44.8 °C and a molecular weight of 202.05 g / mol. The 1H,4H-octafluorobutane used had a purity level above 98 percent by weight.1-Methoxynonafluorobutane (HFC-449mccc or HFE-7100) has an atmospheric boiling point of 61 °C and a molecular weight of 250.06 g / mol. The 1-methoxynonafluorobutane used had a purity level above 99.5 percent by weight and was a mixture of two isomers, 45 to 10 wt% 1-methoxynonafluoro-n-butane (CAS No. 163702-07-6) and 55 to 90 wt% 1-methoxynonafluoroisobutane (CAS No. 163702-08-7).1-Ethoxynonafluorobutane (HFC-569mccc or HFE-7200) has an atmospheric boiling point of 76 °C and a molecular weight of 264.09 g / mol. The 1-ethoxynonafluorobutane used had a purity level above 99.5 percent by weight and was a mixture of two isomers, 45 to 10 wt% 1-ethoxynonafluoro-n-butane (CAS No. 163702-05-4) and 55 to 90 wt% 1-ethoxynonafluoroisobutane (CAS No. 163702-06-5).The following different polyethylenes were used:Polyethylene A was a polyethylene having a density of 0.957 g / cm³ (ISO 1183), a melting point of 134 °C, and a melt flow rate of 0.9 g / 10min (ISO 1133 - 190 °C / 2.16 kg).Polyethylene B was a polyethylene having a density of 0.954 g / cm³ (ISO 1183), a melting point of 133 °C, and a melt flow rate of 0.74 g / 10min (ISO 1133 - 190 °C / 2.16 kg).Polyethylene C was a polyethylene having a density of 0.96 g / cm³ (ISO 1183), a melting point of 134 °C, and a melt flow rate of 1.2 g / 10min (ISO 1133 - 190 °C / 2.16 kg).Polyethylene D was a polyethylene having a density of 0.957 g / cm³ (ISO 1183), a melting point of 134 °C, and a melt flow rate of 0.27 g / 10min (ISO 1133 - 190 °C / 2.16 kg).The ethylene-hexene copolymer used was an ethylene-hexene copolymer having a density of 0.934 g / cm³ (ISO 1183), a melting point of 124 °C, and a melt flow rate of 0.9 g / 10min (ISO 1133 190 °C / 2.16 kg).The polypropylene (PP) used was an isotactic polypropylene with a melting point of 163 °C and a melt flow rate is 4.5 g / 10 min (ISO 1133 - 230 °C / 2.16 kg / ).The polybutene-1 (PB-1) used has a melting point of 116 °C and a melt flow rate of 4 g / 10 min (ISO 1133 - 190°C / 2.16 kg).The poly(4-methyl-1-pentene) (P4M1P) used has a melting point of 233 °C and a melt flow rate of 5 g / 10 min (ISO 1133 - 260 °C / 2.16kg) and 23 g / 10 min (ISO 1133 - 260 °C / 5kg).All polymers were dried during a minimum of 8 hours in a vacuum oven at about 45-50 °C before use.Spinning EquipmentThe apparatus used consisted of two high pressure cylindrical chambers, each equipped with a piston which was adapted to apply pressure to the contents of the vessel. The cylinders had an inside diameter of 1.0 inch (25.4 mm) and each had an internal capacity of 50 cubic centimeters. The cylinders were connected to each other at one end through a 3 / 32 inch (2.3 mm) diameter channel and a mixing chamber containing a series of fine mesh screens was used as a static mixer. In the channel, a Type J thermocouple was in contact with the spin fluid to record the temperature. Mixing was accomplished by forcing the contents of the vessel back and forth between the two cylinders through the static mixer. A spinneret assembly with a quick-acting means for opening the orifice was attached to the channel through a tee. The spinneret assembly consisted of a lead hole with a diameter of 0.25 inch (6.3 mm) and a length of about 2.0 inch (50.8 mm), and a spinneret orifice with a diameter of 0.030 inch (0.762 mm) and a length of 0.030 inch (0.762 mm). A pressure transmitter calibrated at the spin temperature was mounted in the lead hole to measure the pressure of the spin fluid. The pistons were driven by a high-pressure hydraulic system.In operation, the apparatus was charged with polymer pellets and spin agent and a pressure of at least 50 bar was applied to the pistons to compress the charge and avoid the spin fluid from boiling during subsequent heating. The contents were then heated to mixing temperature and held at that temperature for about 30 to 45 minutes during which time a differential pressure was alternatively established between the two cylinders to repeatedly force the contents through the mixing channel from one cylinder to the other to provide mixing and effective formation of a spin fluid. The spin fluid temperature was then increased to the final spin temperature and held there for about 10 to 20 minutes to equilibrate. The pressure of the spin fluid was kept above the cloud point pressure during mixing and during the increase in temperature from the mixing temperature to the spin temperature. Mixing was continued throughout this period. At the end of the mixing cycle, the accumulator was set to the pressure desired for spinning. Next, the valve between the accumulator and the twin piston assembly was opened to reduce the pressure of the spin fluid to the desired spin pressure, and about two to five seconds later, the spinneret orifice was opened to release the spin fluid into conditions of atmospheric pressure. The delay of about two to five seconds corresponds to the residence time in the letdown chamber in a continuous spinning process. The resultant stream of flash-spun fibrils was collected in a stainless-steel open mesh screen basket. During spinning, the spin pressure was recorded just upstream of the spinneret.For cloud point pressure determination, the spinneret assembly was replaced with a view cell assembly containing a 1 / 2 inch (12.3 mm) diameter high-pressure sight glass, through which the contents of the cell could be viewed as they flow through the channel. The window was lit by means of a fiber optic light guide, while the view through the sight glass was displayed using a digital camera. In the cell, a Type J thermocouple was located about 5 mm behind the high-pressure sight glass. The Type J thermocouple and a pressure measuring device located in close proximity to the window measured the pressure and temperature inside the view cell behind the sight glass and the pressure and temperature were continuously monitored by a computer. When, after a period of mixing, a clear, homogeneous spin fluid was established, the temperature was held constant and the differential pressure applied to the pistons was equalized so that the pistons stopped moving. Then, the pressure applied to the spin fluid in the view cell was gradually decreased until phase separation was observed through the sight glass, as the initially clear, homogeneous spin fluid became cloudy in appearance. The temperature and pressure were recorded when the thermocouple became no longer visible. This pressure was the phase separation pressure or cloud point pressure for that spin fluid at that temperature. The pressure was then increased until the spin fluid returned to its transparent state, i.e., until the insoluble phase redissolved, and in this way, two or three repeat cloud point measurements could be made at an approximately constant temperature. Once this data was recorded, mixing was resumed while the spin fluid was heated to the next temperature at which the cloud point pressure was to be measured.ResultsExample 1: Vapor liquid equilibrium for the composition of dichloromethane and 1H,4H-octafluorobutaneFigure 1 shows the calculated vapor liquid equilibrium for the composition of dichloromethane and 1H,4H-octafluorobutane. The azeotropic composition of dichloromethane and 1H,4H-octafluorobutane at 40°C corresponds to about 42.0 wt% dichloromethane and about 58.0 wt% 1H,4H-octafluorobutane. The bubble point pressure for the azeotropic composition is equal to about 130.9 kPa. The azeotropic-like composition of dichloromethane and 1H,4H-octafluorobutane at a 5% deviation from the azeotrope point was found to be from about 29:71 wt% to about 58:42 wt%.Example 2: Cloud point study of polypropyleneFigure 2 shows the cloud point pressure curve of a spin fluid comprising 10 wt% polypropylene and a spin agent of dichloromethane and 1H,4H-octafluorobutane in a 60:40 ratio by weight. This spin fluid comprising 10 wt% polypropylene was found to show a cloud point pressure curve suitable for flash spinning.Example 3: Cloud point study of poly(4-methyl-1-pentene)Figure 3 shows the cloud point pressure curve of a spin fluid comprising 18 wt% poly(4-methyl-1-pentene) and a spin agent of dichloromethane and 1H,4H-octafluorobutane in a 42:58 ratio by weight. This spin fluid comprising 18 wt% polyethylene was found to show a cloud point pressure curve suitable for flash spinning.Examples 4 and 5: Flash spinning performance of polypropyleneIn Example 4 flash spinning was performed on the equipment described in the above for a spin fluid comprising 10 wt% polypropylene and a spin agent of dichloromethane and 1H,4H-octafluorobutane in a 50:50 ratio by weight at a spin temperature of about 210 °C and a spin pressure of about 165 bar.In Example 5 flash spinning was performed on the equipment described in the above for a spin fluid comprising 16 wt% of a polymer blend of polypropylene and poly(4-methyl-1-pentene) in a 80:20 ratio by weight and a spin agent of dichloromethane and 1H,4H-octafluorobutane in a 60:40 ratio by weight at a spin temperature of about 205 °C and a spin pressure of about 103 bar.Example 6: Vapor liquid equilibrium for the mixture dichloromethane and 1-methoxynonafluorobutaneFigure 4 shows the calculated vapor liquid equilibrium for the composition of dichloromethane and 1-methoxynonafluorobutane. The azeotropic composition of dichloromethane and 1-methoxynonafluorobutane at 40°C corresponds to about 54.0 wt% dichloromethane and about 46.0 wt% 1-methoxynonafluorobutane. The bubble point pressure for the azeotropic composition is equal to about 119.7 kPa. The azeotropic-like composition of dichloromethane and 1-methoxynonafluorobutane at a 5% deviation from the azeotrope point was found to be from about 46:54 wt% to about 70:30 wt%.Example 7: Cloud point study of polypropyleneFigure 5 shows the cloud point pressure curve of a spin fluid comprising 7 wt% polypropylene and a spin agent of dichloromethane and 1-methoxynonafluorobutane in a 54:46 ratio by weight. This spin fluid comprising 7 wt% polypropylene was found to show a cloud point pressure curve suitable for flash spinning.Example 8: Cloud point study of polybutene-1Figure 6 shows the cloud point pressure curve of a spin fluid comprising 12 wt% polybutene-1 and a spin agent of dichloromethane and 1-methoxynonafluorobutane in a 54:46 ratio by weight. This spin fluid comprising 12 wt% polybutene-1 was found to show a cloud point pressure curve suitable for flash spinning.Example 9: Cloud point study of poly(4-methyl-1-pentene)Figure 7 shows the cloud point pressure curve of a spin fluid comprising 20 wt% poly(4-methyl-1-pentene) and a spin agent of dichloromethane and 1-methoxynonafluorobutane in a 54:46 ratio by weight. This spin fluid comprising 20 wt% poly(4-methyl-1-pentene) was found to show a cloud point pressure curve suitable for flash spinning.Examples 10 and 11: Flash spinning performance of polypropyleneIn Example 10 flash spinning was performed on the equipment described in the above for a spin fluid comprising 10 wt% polypropylene and a spin agent of dichloromethane and 1-methoxynonafluorobutane in a 64:36 ratio by weight at a spin temperature of about 200 °C and a spin pressure of about 78 bar.In Example 11 flash spinning was performed on the equipment described in the above for a spin fluid comprising 15 wt% polypropylene and a spin agent of dichloromethane and 1-methoxynonafluorobutane in a 54:46 ratio by weight at a spin temperature of about 190 °C and a spin pressure of about 113 bar.Example 12: Vapor liquid equilibrium for the mixture dichloromethane and 1-ethoxynonafluorobutaneFigure 8 shows the calculated vapor liquid equilibrium for the composition of dichloromethane and 1-ethoxynonafluorobutane. The azeotropic composition of dichloromethane and 1-ethoxynonafluorobutane at 40°C corresponds to about 76.0 wt% dichloromethane and about 24.0 wt% 1-ethoxynonafluorobutane. The bubble point pressure for the azeotropic composition is equal to about 105.7 kPa. The azeotropic-like composition of dichloromethane and1-ethoxynonafluorobutane at a 5% deviation from the azeotrope point was found to be from about 65:35 wt% to about 99:1 wt%.Example 13: Cloud point study of polyethyleneFigure 9 shows the cloud point pressure curve of a spin fluid comprising 22 wt% polyethylene C and a spin agent of dichloromethane and1-ethoxynonafluorobutane in a 76:24 ratio by weight. This spin fluid comprising 22 wt% polyethylene was found to show a cloud point pressure curve suitable for flash spinning.Example 14: Cloud point study of ethylene-hexene copolymerFigure 10 shows the cloud point pressure curve of a spin fluid comprising 12 wt% ethylene-hexene copolymer and a spin agent of dichloromethane and 1-ethoxynonafluorobutane in a 76:24 ratio by weight. This spin fluid comprising 12 wt% ethylene-hexene copolymer was found to show a cloud point pressure curve suitable for flash spinning.Example 15: Cloud point study of polypropyleneFigure 11 shows the cloud point pressure curve of a spin fluid comprising 10 wt% polypropylene and a spin agent of dichloromethane and 1-ethoxynonafluorobutane in a 66:34 ratio by weight. This spin fluid comprising 10 wt% polypropylene was found to show a cloud point pressure curve suitable for flash spinning.Example 16: Cloud point study of polypropyleneFigure 12 shows the cloud point pressure curve of a spin fluid comprising 15 wt% polybutene-1 and a spin agent of dichloromethane and 1-ethoxynonafluorobutane in a 66:34 ratio by weight. This spin fluid comprising 15 wt% polybutene-1 was found to show a cloud point pressure curve suitable for flash spinning.Example 17: Cloud point study of poly(4-methyl-1-pentene)Figure 13 shows the cloud point pressure curve of a spin fluid comprising 22 wt% poly(4-methyl-1-pentene) and a spin agent of dichloromethane and 1-ethoxynonafluorobutane in a 66:34 ratio by weight. This spin fluid comprising 22 wt% poly(4-methyl-1-pentene) was found to show a cloud point pressure curve suitable for flash spinning.Examples 18, 19 and 20: Flash spinning performance of polyethyleneIn Example 18 flash spinning was performed on the equipment described in the above for a spin fluid comprising 7 wt% polyethylene A and a spin agent of dichloromethane and 1-ethoxynonafluorobutane in a 76:24 ratio by weight at a spin temperature of about 180 °C and a spin pressure of about 87 bar.In Example 19 flash spinning was performed on the equipment described in the above for a spin fluid comprising 16 wt% polyethylene B and a spin agent of dichloromethane and 1-ethoxynonafluorobutane in a 70:30 ratio by weight at a spin temperature of about 220 °C and a spin pressure of about 167 bar.In Example 20 flash spinning was performed on the equipment described in the above for a spin fluid comprising 22 wt% polyethylene C and a spin agent of dichloromethane and 1-ethoxynonafluorobutane in a 76:24 ratio by weight at a spin temperature of about 210 °C and a spin pressure of about 91 bar.Example 21: Flash spinning performance of ethylene-hexene copolymerIn Example 21 flash spinning was performed on the equipment described in the above for a spin fluid comprising 12 wt% ethylene-hexene copolymer and a spin agent of dichloromethane and 1-ethoxynonafluorobutane in a 76:24 ratio by weight at a spin temperature of about 205 °C and a spin pressure of about 109 bar.Example 22: Flash spinning performance of polypropyleneIn Example 22 flash spinning was performed on the equipment described in the above for a spin fluid comprising 10 wt% polypropylene and a spin agent of dichloromethane and 1-ethoxynonafluorobutane in a 66:34 ratio by weight at a spin temperature of about 214 °C and a spin pressure of about 83 bar.Example 23: Flash spinning performance of a blend of polyethylene and polypropyleneIn Example 23 flash spinning was performed on the equipment described in the above for a spin fluid comprising 16 wt% of a polymer blend of polyethylene D and polypropylene in a 80:20 ratio by weight and a spin agent of dichloromethane and 1-ethoxynonafluorobutane in a 70:30 ratio by weight at a spin temperature of about 214 °C and a spin pressure of about 83 bar.Table 1: Summary of the flash spinning experiments of Examples 4, 5, 10, and 11.Example 4 5 10 11Spin agent component 1 (SA1) DCM DCM DCM DCMSpin agent component 2 (SA2) HFC-338ppc HFC-338ppc HFC-449mccc HFC-449mcccRatio SA1: SA2 (wt%) 50:50 60:40 64:36 54:46GWP* 565 454 173 218Polymer PP PP / P4M1P blend PP PPPolymer concentration (wt%) 10 16 10 15Cloud point pressure (bar) 177 n.a. 86 126Spin temperature (°C) 210 205 200 190Spin pressure (bar) 165 103 78 113* assuming a GWP of 11.2 for the dichloromethane, a GWP of 1119 for the 1H,4H-octafluorobutane (HFC-338ppc) and a GWP of 460 for the 1-methoxynonafluorobutane (HFC-449mccc)Table 2: Summary of the flash spinning experiments of Examples 18, 19, 20, 21, 22 and 23.Example 18 19 20 21 22 23Spin agent component 1 (SA1) DCM DCM DCM DCM DCM DCMSpin agent component 2 (SA2) HFC-569mccc HFC-569mccc HFC-569mccc HFC-569mccc HFC-569mccc HFC-569mcccRatio SA1: SA2 (wt%) 76:24 70:30 76:24 76:24 66:34 70:30GWP* 23 26 23 23 26Polymer PE A PE B PE C ethylene-hexene copolymer PP PE / PP Blend**Polymer concentration (wt%) 7 16 22 12 10 16Cloud point pressure (bar) 105 197 115 126 91 n.a.Spin temperature (°C) 180 220 210 205 214 210Spin pressure (bar) 87 167 91 109 83 166* assuming a GWP of 11.2 for the dichloromethane and a GWP of 60.7 for the 1-ethoxynonafluorobutane (HFC-569mccc)The above examples illustrate that the azeotropic or azeotrope-like compositions of dichloromethane and 1H,4H-octafluorobutane, azeotropic or azeotrope-like compositions of dichloromethane and 1-methoxynonafluorobutane, and azeotropic or azeotrope-like compositions of dichloromethane and 1-ethoxynonafluorobutane can be used as a spin agent for the flash spinning process of different polyolefins, including copolymers and blends for different polymer concentrations, spin temperatures, and spin pressures. This allows an efficient preparation of plexifilamentary fibrils of polyolefins.In addition, the azeotropic or azeotrope-like compositions exhibit a desirably low GWP value of less than 570, or less than 220, or even less than 30. This makes these compositions suitable as replacement for currently used spin agents.Furthermore, the azeotropic or azeotrope-like compositions form a positive homogenous azeotrope with an advantageously low boiling temperature of 40 °C. Such low boiling temperature correlates to a pressure around (or only slightly above) atmospheric pressure.The azeotrope-like compositions which are centered around the azeotrope point exhibit only small differences between the bubble point pressure and the dew point pressure. This has the advantage that the azeotropic or azeotrope-like compositions do not change significantly during the different steps of the spin agent recovery process and thus allow the spin agent to be re-used / recycled in a commercial process.OTHER EMBODIMENTS1. In some embodiments, the present application provides an azeotropic or azeotrope-like composition comprising(1) dichloromethane and 1H,4H-octafluorobutane,(2) dichloromethane and 1-methoxynonafluorobutane, or(3) dichloromethane and 1-ethoxynonafluorobutane.2. The azeotropic or azeotrope-like composition of embodiment 1 comprising from about 18 to about 63 weight percent dichloromethane and from about 82 to about 37 weight percent 1H,4H-octafluorobutane.3. The azeotropic or azeotrope-like composition of embodiment 2 consisting essentially of or consisting of from about 18 to about 63 weight percent dichloromethane and from about 82 to about 37 weight percent 1H,4H-octafluorobutane.4. The azeotropic or azeotrope-like composition of any one of embodiments 2 to 3 comprising from about 24 to about 54 weight percent dichloromethane and from about 76 to about 46 weight percent 1H,4H-octafluorobutane.5. The azeotropic or azeotrope-like composition of embodiment 4 consisting essentially of or consisting of from about 24 to about 54 weight percent dichloromethane and from about 76 to about 46 weight percent 1H,4H-octafluorobutane.6. The azeotropic or azeotrope-like composition of any one of embodiments 2 to 5 boiling at a temperature of about -20 °C to about 100 °C at a pressure of about 8 kPa to about 715 kPa.7. The azeotropic or azeotrope-like composition of any one of embodiments 2 to 6 comprising from about 24 to about 61 weight percent dichloromethane and from about 76 to about 39 weight percent 1H,4H-octafluorobutane.8. The azeotropic or azeotrope-like composition of embodiment 7 consisting essentially of or consisting of from about 24 to about 61 weight percent dichloromethane and from about 76 to about 39 weight percent 1H,4H-octafluorobutane.9. The azeotropic or azeotrope-like composition of any one of embodiments 7 to 8 comprising from about 30 to about 53 weight percent dichloromethane and from about 70 to about 47 weight percent 1H,4H-octafluorobutane.10. The azeotropic or azeotrope-like composition of embodiment 9 consisting essentially of or consisting of from about 30 to about 53 weight percent dichloromethane and from about 70 to about 47 weight percent 1H,4H-octafluorobutane.11. The azeotropic or azeotrope-like composition of any one of embodiments 7 to 10 boiling at a temperature of about -20 °C to about 60 °C at a pressure of about 8 kPa to about 245 kPa.12. The azeotropic or azeotrope-like composition of any one of embodiments 2 to 11 comprising from about 29 to about 58 weight percent dichloromethane and from about 71 to about 42 weight percent 1H,4H-octafluorobutane.13. The azeotropic or azeotrope-like composition of embodiment 12 consisting essentially of or consisting of from about 29 to about 58 weight percent dichloromethane and from about 71 to about 42 weight percent 1H,4H-octafluorobutane.14. The azeotropic or azeotrope-like composition of any one of embodiments 12 to 13 comprising from about 32 to about 52 weight percent dichloromethane and from about 68 to about 48 weight percent 1H,4H-octafluorobutane.15. The azeotropic or azeotrope-like composition of embodiment 14 consisting essentially of or consisting of from about 32 to about 52 weight percent dichloromethane and from about 68 to about 48 weight percent 1H,4H-octafluorobutane.16. The azeotropic or azeotrope-like composition of any one of embodiments 12 to 15 boiling at a temperature of about -20 °C to about 40 °C at a pressure of about 8 kPa to about 131 kPa.17. The azeotropic composition of any one of the embodiments 2 to 16 consisting essentially of or consisting of from about 38 to about 45 weight percent dichloromethane and from about 62 to about 55 weight percent 1H,4H-octafluorobutane.18. The azeotropic composition of embodiment 17 boiling at a temperature of about -20 °C to about 100 °C at pressure of about 8 kPa to about 715 kPa.19. The azeotropic composition of any one of the embodiments 2 to 18 consisting essentially of or consisting of about 45.0 weight percent dichloromethane and about 55.0 weight percent 1H,4H-octafluorobutane.20. The azeotropic composition of embodiment 19 boiling at temperature of about -20 °C at a pressure of about 8.9 kPa.21. The azeotropic composition of any one of the embodiments 2 to 18 consisting essentially of or consisting of about 43.0 weight percent dichloromethane and about 57.0 weight percent 1H,4H-octafluorobutane.22. The azeotropic composition of embodiment 21 boiling at temperature of about 20 °C at a pressure of about 62.0 kPa.23. The azeotropic composition of any one of the embodiments 2 to 18 consisting essentially of or consisting of about 42.0 weight percent dichloromethane and about 58.0 weight percent 1H,4H-octafluorobutane.24. The azeotropic composition of embodiment 23 boiling at temperature of about 40 °C at a pressure of about 130.9 kPa.25. The azeotropic composition of any one of the embodiments 2 to 18 consisting essentially of or consisting of about 40.7 weight percent dichloromethane and about 59.3 weight percent 1H,4H-octafluorobutane.26. The azeotropic composition of embodiment 25 boiling at temperature of about 60 °C at a pressure of about 248.7 kPa.27. The azeotropic composition of any one of the embodiments 2 to 18 consisting essentially of or consisting of about 38.1 weight percent dichloromethane and about 61.9 weight percent 1H,4H-octafluorobutane.28. The azeotropic composition of embodiment 27 boiling at temperature of about 100 °C at a pressure of about 715 kPa.29. The azeotropic composition of any one of the embodiments 2 to 18 consisting essentially of or consisting of about 42.4 weight percent dichloromethane and about 57.6 weight percent 1H,4H-octafluorobutane.30. The azeotropic composition of embodiment 29 boiling at temperature of about 32.8 °C at a pressure of about 101.3 kPa.31. The azeotropic or azeotrope-like composition of embodiment 1 comprising from about 38 to about 72 weight percent dichloromethane and from about 62 to about 28 weight percent 1-methoxynonafluorobutane.32. The azeotropic or azeotrope-like composition of embodiment 31 consisting essentially of or consisting of from about 38 to about 72 weight percent dichloromethane and from about 62 to about 28 weight percent 1-methoxynonafluorobutane.33. The azeotropic or azeotrope-like composition of embodiment 31 or 32 comprising from about 41 to about 66 weight percent dichloromethane and from about 59 to about 34 weight percent 1-methoxynonafluorobutane.34. The azeotropic or azeotrope-like composition of embodiment 32 consisting essentially of or consisting of from about 41 to about 66 weight percent dichloromethane and from about 59 to about 34 weight percent 1-methoxynonafluorobutane.35. The azeotropic or azeotrope-like composition of any one of embodiments 31 to 34 boiling at a temperature of about 0 °C to about 100 °C at a pressure of about 21 kPa to about 698 kPa.36. The azeotropic or azeotrope-like composition of any one of embodiments 31 to 35 comprising from about 43 to about 72 weight percent dichloromethane and from about 57 to about 28 weight percent 1-methoxynonafluorobutane.37. The azeotropic or azeotrope-like composition of embodiment 36 consisting essentially of or consisting of from about 43 to about 72 weight percent dichloromethane and from about 57 to about 28 weight percent 1-methoxynonafluorobutane.38. The azeotropic or azeotrope-like composition of embodiment 36 or 37 comprising from about 45 to about 66 weight percent dichloromethane and from about 55 to about 34 weight percent 1-methoxynonafluorobutane.39. The azeotropic or azeotrope-like composition of embodiment 38 consisting essentially of or consisting of from about 45 to about 66 weight percent dichloromethane and from about 55 to about 34 weight percent 1-methoxynonafluorobutane.40. The azeotropic or azeotrope-like composition of any one of embodiments 36 to 39 boiling at a temperature of about 0 °C to about 60 °C at a pressure of about 21 kPa to about 232 kPa.41. The azeotropic or azeotrope-like composition of any one of embodiments 31 to 40 comprising from about 46 to about 72 weight percent dichloromethane and from about 54 to about 28 weight percent 1-methoxynonafluorobutane.42. The azeotropic or azeotrope-like composition of embodiment 41 consisting essentially of or consisting of from about 46 to about 72 weight percent dichloromethane and from about 54 to about 28 weight percent 1-methoxynonafluorobutane.43. The azeotropic or azeotrope-like composition of embodiment 41 or 42 comprising from about 48 to about 66 weight percent dichloromethane and from about 52 to about 34 weight percent 1-methoxynonafluorobutane.44. The azeotropic or azeotrope-like composition of embodiment 43 consisting essentially of or consisting of from about 48 to about 66 weight percent dichloromethane and from about 52 to about 34 weight percent 1-methoxynonafluorobutane.45. The azeotropic or azeotrope-like composition of any one of embodiments 41 to 44 boiling at a temperature of about 0 °C to about 40 °C at a pressure of about 21 kPa to about 120 kPa.46. The azeotropic composition of any one of the embodiments 31 to 45 consisting essentially of or consisting of from about 50 to about 58 weight percent dichloromethane and from about 50 to about 42 weight percent 1-methoxynonafluorobutane.47. The azeotropic composition of embodiment 46 boiling at a temperature of about 0°C to about 100 °C at pressure of about 22 kPa to about 698 kPa.48. The azeotropic composition of any one of the embodiments 31 to 47 consisting essentially of or consisting of about 58.0 weight percent dichloromethane and about 42.0 weight percent 1-methoxynonafluorobutane.49. The azeotropic composition of embodiment 48 boiling at temperature of about 0 °C at a pressure of about 22.2 kPa.50. The azeotropic composition of any one of the embodiments 31 to 47 consisting essentially of or consisting of about 56.0 weight percent dichloromethane and about 44.0 weight percent 1-methoxynonafluorobutane.51. The azeotropic composition of embodiment 50 boiling at temperature of about 20 °C at a pressure of about 55.3 kPa.52. The azeotropic composition of any one of the embodiments 31 to 47 consisting essentially of or consisting of about 54.0 weight percent dichloromethane and about 46.0 weight percent 1-methoxynonafluorobutane.53. The azeotropic composition of embodiment 52 boiling at temperature of about 40 °C at a pressure of about 119.7 kPa.54. The azeotropic composition of any one of the embodiments 31 to 47 consisting essentially of or consisting of about 52.0 weight percent dichloromethane and about 48.0 weight percent 1-methoxynonafluorobutane.55. The azeotropic composition of embodiment 54 boiling at temperature of about 60 °C at a pressure of about 232 kPa.56. The azeotropic composition of any one of the embodiments 31 to 47 consisting essentially of or consisting of about 50.0 weight percent dichloromethane and about 50.0 weight percent 1-methoxynonafluorobutane.57. The azeotropic composition of embodiment 56 boiling at temperature of about 100 °C at a pressure of about 689 kPa.58. The azeotropic composition of any one of the embodiments 31 to 47 consisting essentially of or consisting of about 54.0 weight percent dichloromethane and about 46.0 weight percent 1-methoxynonafluorobutane.59. The azeotropic composition of embodiment 58 boiling at temperature of about 35.4 °C at a pressure of about 101.3 kPa.60. The azeotropic or azeotrope-like composition of embodiment 1 comprising from about 54 to about 99 weight percent dichloromethane and from about 46 to about 1 weight percent 1-ethoxynonafluorobutane.61. The azeotropic or azeotrope-like composition of embodiment 60 consisting essentially of or consisting of from about 54 to about 99 weight percent dichloromethane and from about 46 to about 1 weight percent 1-ethoxynonafluorobutane.62. The azeotropic or azeotrope-like composition of embodiment 60 or 61 comprising from about 57 to about 99 weight percent dichloromethane and from about 43 to about 1 weight percent 1-ethoxynonafluorobutane.63. The azeotropic or azeotrope-like composition of embodiment 62 consisting essentially of or consisting of from about 57 to about 99 weight percent dichloromethane and from about 43 to about 1 weight percent 1-ethoxynonafluorobutane.64. The azeotropic or azeotrope-like composition of any one of embodiments 60 to 63 boiling at a temperature of about -20 °C to about 100 °C at a pressure of about 6 kPa to about 604 kPa.65. The azeotropic or azeotrope-like composition of any one of embodiments 60 to 64 comprising from about 61 to about 99 weight percent dichloromethane and from about 39 to about 1 weight percent 1-ethoxynonafluorobutane.66. The azeotropic or azeotrope-like composition of embodiment 65 consisting essentially of or consisting of from about 61 to about 99 weight percent dichloromethane and from about 39 to about 1 weight percent 1-ethoxynonafluorobutane.67. The azeotropic or azeotrope-like composition of embodiment 65 or 66 comprising from about 64 to about 99 weight percent dichloromethane and from about 36 to about 1 weight percent 1-ethoxynonafluorobutane.68. The azeotropic or azeotrope-like composition of embodiment 67 consisting essentially of or consisting of from about 64 to about 99 weight percent dichloromethane and from about 36 to about 1 weight percent 1-ethoxynonafluorobutane.69. The azeotropic or azeotrope-like composition of any one of embodiments 65 to 68 boiling at a temperature of about -20 °C to about 60 °C at a pressure of about 6 kPa to about 205 kPa.70. The azeotropic or azeotrope-like composition of any one of embodiments 60 to 69 comprising from about 65 to about 99 weight percent dichloromethane and from about 35 to about 1 weight percent 1-ethoxynonafluorobutane.71. The azeotropic or azeotrope-like composition of embodiment 70 consisting essentially of or consisting of from about 65 to about 99 weight percent dichloromethane and from about 35 to about 1 weight percent 1-ethoxynonafluorobutane.72. The azeotropic or azeotrope-like composition of embodiment 70 or 71 comprising from about 67 to about 99 weight percent dichloromethane and from about 33 to about 1 weight percent 1-ethoxynonafluorobutane.73. The azeotropic or azeotrope-like composition of embodiment 72 consisting essentially of or consisting of from about 67 to about 99 weight percent dichloromethane and from about 33 to about 1 weight percent 1-ethoxynonafluorobutane.74. The azeotropic or azeotrope-like composition of any one of embodiments 70 to 73 boiling at a temperature of about -20 °C to about 40 °C at a pressure of about 6 kPa to about 106 kPa.75. The azeotropic composition of any one of the embodiments 60 to 74 consisting essentially of or consisting of from about 67 to about 84 weight percent dichloromethane and from about 33 to about 16 weight percent 1-ethoxynonafluorobutane.76. The azeotropic composition of embodiment 75 boiling at a temperature of about -20 °C to about 100 °C at pressure of about 6 kPa to about 604 kPa.77. The azeotropic composition of any one of the embodiments 60 to 76 consisting essentially of or consisting of about 84.0 weight percent dichloromethane and about 16.0 weight percent 1-ethoxynonafluorobutane.78. The azeotropic composition of embodiment 77 boiling at temperature of about -20 °C at a pressure of about 6.6 kPa.79. The azeotropic composition of any one of the embodiments 60 to 76 consisting essentially of or consisting of about 79.0 weight percent dichloromethane and about 21.0 weight percent 1-ethoxynonafluorobutane.80. The azeotropic composition of embodiment 79 boiling at temperature of about 20 °C at a pressure of about 48.9 kPa.81. The azeotropic composition of any one of the embodiments 60 to 76 consisting essentially of or consisting of about 76.0 weight percent dichloromethane and about 24.0 weight percent 1-ethoxynonafluorobutane.82. The azeotropic composition of embodiment 81 boiling at temperature of about 40 °C at a pressure of about 105.7 kPa.83. The azeotropic composition of any one of the embodiments 60 to 76 consisting essentially of or consisting of about 73.0 weight percent dichloromethane and about 27.0 weight percent 1-ethoxynonafluorobutane.84. The azeotropic composition of embodiment 83 boiling at temperature of about 60 °C at a pressure of about 205 kPa.85. The azeotropic composition of any one of the embodiments 60 to 76 consisting essentially of or consisting of about 66.9 weight percent dichloromethane and about 33.1 weight percent 1-ethoxynonafluorobutane.86. The azeotropic composition of embodiment 85 boiling at temperature of about 100 °C at a pressure of about 604 kPa.87. The azeotropic composition of any one of the embodiments 60 to 76 consisting essentially of or consisting of about 76.0 weight percent dichloromethane and about 24.0 weight percent 1-ethoxynonafluorobutane.88. The azeotropic composition of embodiment 87 boiling at temperature of about 38.8 °C at a pressure of about 101.3 kPa.89. In some embodiments, the present application provides a spin fluid for flash spinning comprising(a) from about 6 to about 24 weight percent weight percent of a polyolefin, based on the total amount of the spin fluid, and(b) a spin agent, wherein the spin agent comprises or consists essentially of an azeotropic or azeotrope-like composition comprising(1) dichloromethane and 1H,4H-octafluorobutane,(2) dichloromethane and 1-methoxynonafluorobutane, or(3) dichloromethane and 1-ethoxynonafluorobutane.90. The spin fluid of embodiment 89 comprising from about 6 to about 20 weight percent of a polyolefin, based on the total amount of the spin fluid, or from about 8 to about 20 weight percent of a polyolefin, based on the total amount of the spin fluid, or from about 8 to about 16 weight percent of a polyolefin, based on the total amount of the spin fluid, or from about 8 to about 14 weight percent of a polyolefin, based on the total amount of the spin fluid.91. The spin fluid of embodiment 89 or 90 comprising (a) from about 6 to about 20 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1, or a poly(4-methyl-1-pentene), based on the total amount of the spin fluid, or from about 8 to about 20 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1, or a poly(4-methyl-1-pentene), based on the total amount of the spin fluid, or from about 8 to about 16 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1, or a poly(4-methyl-1-pentene), based on the total amount of the spin fluid, or from about 8 to about 14 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1, or a poly(4-methyl-1-pentene), based on the total amount of the spin fluid; and (b) a spin agent, wherein the spin agent comprises or consists essentially of an azeotropic or azeotrope-like composition comprising dichloromethane and 1-methoxynonafluorobutane.92. The spin fluid of any one of embodiments 89 to 91 comprising from about 76 to about 94 weight percent of the spin agent, based on the total amount of the spin fluid, or from about 80 to about 94 weight percent of the spin agent, based on the total amount of the spin fluid, or from about 80 to about 92 weight percent of the spin agent, based on the total amount of the spin fluid, or from about 84 to about 92 weight percent of the spin agent, based on the total amount of the spin fluid, or from about 86 to about 92 weight percent of the spin agent, based on the total amount of the spin fluid.93. The spin fluid of any one of embodiments 89 to 92, wherein the spin agent consists essentially of or consists of from about 32 to about 62 weight percent dichloromethane and from about 68 to about 38 weight percent 1H,4H-octafluorobutane, or from about 35 to about 58 weight percent dichloromethane and from about 65 to about 42 weight percent 1H,4H-octafluorobutane.94. The spin fluid of any one of embodiments 89 to 92, wherein the spin agent consists essentially of or consists of from about 40 to about 61 weight percent dichloromethane and from about 60 to about 39 weight percent 1H,4H-octafluorobutane, or from about 52 to about 60 weight percent dichloromethane and from about 48 to about 40 weight percent 1H,4H-octafluorobutane, or from about 48 to about 62 weight percent dichloromethane and from about 52 to about 38 weight percent 1H,4H-octafluorobutane.95. The spin fluid of any one of embodiments 89 to 92, wherein the spin agent consists essentially of or consists of from about 46 to about 70 weight percent dichloromethane and from about 54 to about 30 weight percent 1-methoxynonafluorobutane, or from about 48 to about 65 weight percent dichloromethane and from about 52 to about 35 weight percent 1-methoxynonafluorobutane, or from about 50 to about 65 weight percent dichloromethane and from about 50 to about 35 weight percent 1-methoxynonafluorobutane.96. The spin fluid of any one of embodiments 89 to 92, wherein the spin agent consists essentially of or consists of from about 70 to about 85 weight percent dichloromethane and from about 30 to about 15 weight percent 1-ethoxynonafluorobutane, or from about 75 to about 85 weight percent dichloromethane and from about 25 to about 15 weight percent 1-ethoxynonafluorobutane, or from about 75 to about 80 weight percent dichloromethane and from about 25 to about 20 weight percent 1-ethoxynonafluorobutane.97. The spin fluid of any one of embodiments 89 to 92, wherein the spin agent consists essentially of or consists of from about 66 to about 70 weight percent dichloromethane and from about 34 to about 30 weight percent 1-ethoxynonafluorobutane.98. The spin fluid of any one of embodiments 89 to 97, wherein the polyolefin is selected from the group consisting of polyethylene, polypropylene, polybutene-1, poly(4-methyl-1-pentene), and blends / mixtures thereof.99. The spin fluid of embodiment 98, wherein the polyethylene is a high-density polyethylene (HDPE), a blend of a high-density polyethylene (HDPE) with a low-density polyethylene (LDPE), or a blend of a high-density polyethylene (HDPE) with a linear low-density polyethylene (LLDPE).100. The spin fluid of any one of embodiments 89 to 99 comprising about 6 to about 24 weight percent, or about 6 to about 20 weight percent, or about 8 to about 20 weight percent, or about 8 to about 16 weight percent, or about 8 to about 14 weight percent of a polyethylene, based on the total amount of the spin fluid, and a spin agent, wherein the spin agent consists essentially of or consists of from about 70 to about 85 weight percent dichloromethane and from about 30 to about 15 weight percent 1-ethoxynonafluorobutane, or from about 75 to about 85 weight percent dichloromethane and from about 25 to about 15 weight percent 1-ethoxynonafluorobutane, or from about 75 to about 80 weight percent dichloromethane and from about 25 to about 20 weight percent 1-ethoxynonafluorobutane.101. The spin fluid of any one of embodiments 89 to 98 comprising about 15 to about 24 weight percent of a polypropylene, a polybutene-1, or a poly(4-methyl-1-pentene), based on the total amount of the spin fluid, and a spin agent, wherein the spin agent consists essentially of or consists of from about 32 to about 62 weight percent dichloromethane and from about 68 to about 38 weight percent 1H,4H-octafluorobutane, or from about 35 to about 58 weight percent dichloromethane and from about 65 to about 42 weight percent 1H,4H-octafluorobutane, or from about 40 to about 61 weight percent dichloromethane and from about 60 to about 39 weight percent 1H,4H-octafluorobutane, or from about 52 to about 60 weight percent dichloromethane and from about 48 to about 40 weight percent 1H,4H-octafluorobutane, or from about 48 to about 62 weight percent dichloromethane and from about 52 to about 38 weight percent 1H,4H-octafluorobutane.102. The spin fluid of any one of embodiments 89 to 98 comprising about 15 to about 24 weight percent of a polypropylene, a polybutene-1, or a poly(4-methyl-1-pentene), based on the total amount of the spin fluid, and a spin agent, wherein the spin agent consists essentially of or consists of from about 46 to about 70 weight percent dichloromethane and from about 54 to about 30 weight percent 1-methoxynonafluorobutane, or from about 48 to about 65 weight percent dichloromethane and from about 52 to about 35 weight percent 1-methoxynonafluorobutane, or from about 50 to about 65 weight percent dichloromethane and from about 50 to about 35 weight percent 1-methoxynonafluorobutane.103. The spin fluid of any one of embodiments 89 to 98 comprising about 15 to about 24 weight percent of a polypropylene, a polybutene-1, or a poly(4-methyl-1-pentene), based on the total amount of the spin fluid, and a spin agent, wherein the spin agent consists essentially of or consists of from about 66 to about 70 weight percent dichloromethane and from about 34 to about 30 weight percent 1-ethoxynonafluorobutane.104. The spin fluid of any one of embodiments 89 to 103, wherein the spin agent additionally comprises an additive, selected from antioxidants, acid scavengers, and blends thereof.105. In some embodiments, the present application provides a process for the preparation of plexifilamentary fibrils of polyolefin comprising the steps of:(i) generating a spin fluid comprising(a) about 6 to about 24 weight percent of a polyolefin, based on the total amount of the spin fluid, and(b) a spin agent, and(ii) flash spinning the spin fluid at a pressure above the vapor pressure of the spin fluid into a region of essentially atmospheric pressure to form plexifilamentary fibrils of the polyolefin;wherein the spin agent comprises or consists essentially of(1) an azeotropic or azeotrope-like composition comprising dichloromethane and 1H,4H-octafluorobutane,(2) an azeotropic or azeotrope-like composition comprising dichloromethane and 1-methoxynonafluorobutane, or(3) an azeotropic or azeotrope-like composition comprising dichloromethane and 1-ethoxynonafluorobutane.106. The process of embodiment 105, wherein the spin fluid comprises from about 6 to about 20 weight percent of a polyolefin, based on the total amount of the spin fluid, or from about 8 to about 20 weight percent of a polyolefin, based on the total amount of the spin fluid, or from about 8 to about 16 weight percent of a polyolefin, based on the total amount of the spin fluid, or from about 8 to about 14 weight percent of a polyolefin, based on the total amount of the spin fluid.107. The process of embodiment 105 or 106, wherein the spin fluid comprises (a) from about 6 to about 20 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1, or a poly(4-methyl-1-pentene), based on the total amount of the spin fluid, or from about 8 to about 20 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1, or a poly(4-methyl-1-pentene), based on the total amount of the spin fluid, or from about 8 to about 16 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1, or a poly(4-methyl-1-pentene), based on the total amount of the spin fluid, or from about 8 to about 14 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1, or a poly(4-methyl-1-pentene), based on the total amount of the spin fluid; and (b) a spin agent, wherein the spin agent comprises or consists essentially of an azeotropic or azeotrope-like composition comprising dichloromethane and 1-methoxynonafluorobutane.108. The process of any one of embodiments 105 to 107, wherein the spin fluid comprises from about 76 to about 94 weight percent of the spin agent, based on the total amount of the spin fluid, or from about 80 to about 94 weight percent of the spin agent, based on the total amount of the spin fluid, or from about 80 to about 92 weight percent of the spin agent, based on the total amount of the spin fluid, or from about 84 to about 92 weight percent of the spin agent, based on the total amount of the spin fluid, or from about 86 to about 92 weight percent of the spin agent, based on the total amount of the spin fluid.109. The process of any one of embodiments 105 to 108, wherein the spin agent consists essentially of or consists of from about 32 to about 62 weight percent dichloromethane and from about 68 to about 38 weight percent 1H,4H-octafluorobutane, or from about 35 to about 58 weight percent dichloromethane and from about 65 to about 42 weight percent 1H,4H-octafluorobutane.110. The process of any one of embodiments 105 to 109, wherein the spin agent consists essentially of or consists of from about 40 to about 61 weight percent dichloromethane and from about 60 to about 39 weight percent 1H,4H-octafluorobutane, or from about 52 to about 60 weight percent dichloromethane and from about 48 to about 40 weight percent 1H,4H-octafluorobutane, or from about 48 to about 62 weight percent dichloromethane and from about 52 to about 38 weight percent 1H,4H-octafluorobutane.111. The process of any one of embodiments 105 to 109, wherein the spin agent consists essentially of or consists of from about 46 to about 70 weight percent dichloromethane and from about 54 to about 30 weight percent 1-methoxynonafluorobutane, or from about 48 to about 65 weight percent dichloromethane and from about 52 to about 35 weight percent 1-methoxynonafluorobutane, or from about 50 to about 65 weight percent dichloromethane and from about 50 to about 35 weight percent 1-methoxynonafluorobutane.112. The process of any one of embodiments 105 to 109, wherein the spin agent consists essentially of or consists of from about 70 to about 85 weight percent dichloromethane and from about 30 to about 15 weight percent 1-ethoxynonafluorobutane, or from about 75 to about 85 weight percent dichloromethane and from about 25 to about 15 weight percent 1-ethoxynonafluorobutane, or from about 75 to about 80 weight percent dichloromethane and from about 25 to about 20 weight percent 1-ethoxynonafluorobutane.113. The process of any one of embodiments 105 to 109, wherein the spin agent consists essentially of or consists of from about 66 to about 70 weight percent dichloromethane and from about 34 to about 30 weight percent 1-ethoxynonafluorobutane.114. The process of any one of embodiments 105 to 113, wherein the polyolefin is selected from the group consisting of polyethylene, polypropylene, polybutene-1, poly(4-methyl-1-pentene), and blends / mixtures thereof.115. The process of embodiment 114, wherein the polyethylene is a high-density polyethylene (HDPE), a blend of a high-density polyethylene (HDPE) with a low-density polyethylene (LDPE), or a blend of a high-density polyethylene (HDPE) with a linear low-density polyethylene (LLDPE).116. The process of any one of embodiments 105 to 115, wherein the spin fluid comprises about 6 to about 24 weight percent, or about 6 to about 20 weight percent, or about 8 to about 20 weight percent, or about 8 to about 16 weight percent, or about 8 to about 14 weight percent of a polyethylene, based on the total amount of the spin fluid, and a spin agent, wherein the spin agent consists essentially of or consists of from about 70 to about 85 weight percent dichloromethane and from about 30 to about 15 weight percent 1-ethoxynonafluorobutane, or from about 75 to about 85 weight percent dichloromethane and from about 25 to about 15 weight percent 1-ethoxynonafluorobutane, or from about 75 to about 80 weight percent dichloromethane and from about 25 to about 20 weight percent 1-ethoxynonafluorobutane.117. The process of any one of embodiments 105 to 114, wherein the spin fluid comprises about 15 to about 24 weight percent of a polypropylene, a polybutene-1, or a poly(4-methyl-1-pentene), based on the total amount of the spin fluid, and a spin agent, wherein the spin agent consists essentially of or consists of from about 32 to about 62 weight percent dichloromethane and from about 68 to about 38 weight percent 1H,4H-octafluorobutane, or from about 35 to about 58 weight percent dichloromethane and from about 65 to about 42 weight percent 1H,4H-octafluorobutane, or from about 40 to about 61 weight percent dichloromethane and from about 60 to about 39 weight percent 1H,4H-octafluorobutane, or from about 52 to about 60 weight percent dichloromethane and from about 48 to about 40 weight percent 1H,4H-octafluorobutane, or from about 48 to about 62 weight percent dichloromethane and from about 52 to about 38 weight percent 1H,4H-octafluorobutane.118. The process of any one of embodiments 105 to 114, wherein the spin fluid comprises about 15 to about 24 weight percent of a polypropylene, a polybutene-1, or a poly(4-methyl-1-pentene), based on the total amount of the spin fluid, and a spin agent, wherein the spin agent consists essentially of or consists of from about 46 to about 70 weight percent dichloromethane and from about 54 to about 30 weight percent 1-methoxynonafluorobutane, or from about 48 to about 65 weight percent dichloromethane and from about 52 to about 35 weight percent 1-methoxynonafluorobutane, or from about 50 to about 65 weight percent dichloromethane and from about 50 to about 35 weight percent 1-methoxynonafluorobutane.119. The process of any one of embodiments 105 to 114, wherein the spin fluid comprises about 15 to about 24 weight percent of a polypropylene, a polybutene-1, or a poly(4-methyl-1-pentene), based on the total amount of the spin fluid, and a spin agent, wherein the spin agent consists essentially of or consists of from about 66 to about 70 weight percent dichloromethane and from about 34 to about 30 weight percent 1-ethoxynonafluorobutane.120. The process of any one of embodiments 105 to 119, wherein the spin agent additionally comprises an additive, selected from antioxidants, acid scavengers, and blends thereof.121. In some embodiments, the present application provides a use of the spin fluid of any of embodiments 89 to 104 for preparing of plexifilamentary fibrils of polymer by flash spinning.122. The plexifilamentary fibrils of polymer obtainable by the process of any one of embodiments 105 to 120.123. A sheet of nonwoven flash-spun plexifilamentary fibrils comprising plexifilamentary fibrils of polymer of embodiment 122.124. The sheet of embodiment 123, wherein the sheet is a collected sheet, a consolidated sheet, a bonded sheet, or a softened sheet.125. A bonded sheet obtainable by thermally or mechanically bonding the consolidated sheet of embodiment 124.126. A softened sheet obtainable by softening the consolidated sheet of embodiment 124 or by softening the bonded sheet of embodiment 125.127. A multilayer sheet comprising two or more sheets wherein at least one sheet is a sheet according to any one of embodiments 123 to 126.128. An article comprising plexifilamentary fibrils of polymer of embodiment 122 and / or a sheet of any one of embodiments 123 to 126 and / or a multilayer sheet of embodiment 127.129. The article of embodiment 128 which is selected from garment, protective apparel, house wrap, roof lining, car covers, cargo covers, medical and non-medical packaging, filtration media, print media, tags and labels, and accessories.130. The article of embodiment 129 wherein the garment is protective apparel.While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example, and not limitation. It will be apparent to persons skilled in the relevant art(s) that various changes in form and detail can be made therein without departing from the spirit and scope of the present invention. Thus, it should be appreciated that, while the invention has been described with reference to the above exemplary embodiments, other embodiments are within the scope of the claims. Moreover, it should be understood that the exemplary embodiments described herein may be combined to form other embodiments. After reading the above description, it will be apparent to one skilled in the relevant art(s) how to implement the invention in alternative embodiments. Thus, the present invention should not be limited by any of the above-described exemplary embodiments.

Claims

1. An azeotropic or azeotrope-like composition comprising(1) dichloromethane and 1H,4H-octafluorobutane,(2) dichloromethane and 1-methoxynonafluorobutane, or(3) dichloromethane and 1-ethoxynonafluorobutane.

2. The azeotropic or azeotrope-like composition of claim 1 comprising from about 18 to about 63 weight percent dichloromethane and from about 82 to about 37 weight percent 1H,4H-octafluorobutane.

3. The azeotropic composition of any one of claims 1 or 2 consisting essentially of from about 38 to about 45 weight percent dichloromethane and from about 62 to about 55 weight percent 1H,4H-octafluorobutane.

4. The azeotropic composition of claim 3 boiling at a temperature of about -20 °C to about 100 °C at a pressure of about 8 kPa to about 715 kPa.

5. The azeotropic or azeotrope-like composition of claim 1 comprising from about 38 to about 72 weight percent dichloromethane and from about 62 to about 28 weight percent 1-methoxynonafluorobutane.

6. The azeotropic composition of any one of claims 1 or 5 consisting essentially of from about 50 to about 58 weight percent dichloromethane and from about 50 to about 42 weight percent 1-methoxynonafluorobutane.

7. The azeotropic composition of claim 6 boiling at a temperature of about -20 °C to about 100 °C at a pressure of about 21 kPa to about 698 kPa.

8. The azeotropic or azeotrope-like composition of claim 1 comprising from about 54 to about 99 weight percent dichloromethane and from about 46 to about 1 weight percent 1-ethoxynonafluorobutane.

9. The azeotropic composition of any one of claims 1 or 8 consisting essentially of from about 67 to about 84 weight percent dichloromethane and from about 33 to about 16 weight percent 1-ethoxynonafluorobutane.

10. The azeotropic composition of claim 9 boiling at a temperature of about -20 °C to about 100 °C at a pressure of about 6 kPa to about 604 kPa.

11. A spin fluid for flash spinning comprising(a) from about 6 to about 24 weight percent of a polyolefin, based on the total amount of the spin fluid, and(b) a spin agent, wherein the spin agent comprises an azeotropic or azeotrope-like composition comprising(1) dichloromethane and 1H,4H-octafluorobutane,(2) dichloromethane and 1-methoxynonafluorobutane, or(3) dichloromethane and 1-ethoxynonafluorobutane.

12. The spin fluid of claim 11 comprising from about 76 to about 94 weight percent of the spin agent, based on the total amount of the spin fluid, or from about 80 to about 94 weight percent of the spin agent, based on the total amount of the spin fluid.

13. The spin fluid of claims 11 or 12, wherein the polyolefin is selected from the group consisting of polyethylene, polypropylene, polybutene-1, poly(4-methyl-1-pentene), and blends / mixtures thereof.

14. The spin fluid of any one of claims 11 to 13, wherein the spin agent comprises an azeotropic or azeotrope-like composition which(1) consists essentially of or consists of from about 32 to about 62 weight percent dichloromethane and from about 68 to than about 38 weight percent 1H,4H-octafluorobutane,(2) consists essentially of or consists of from about 46 to about 70 weight percent dichloromethane and from about 54 to about 30 weight percent 1-methoxynonafluorobutane, or(3) consists essentially of or consists of from about 66 to about 85 weight percent dichloromethane and from about 34 to about 15 weight percent 1-ethoxynonafluorobutane.

15. A process for the preparation of plexifilamentary fibrils of polyolefin which comprises the steps of:(i) generating a spin fluid comprising(a) from about 6 to about 24 weight percent of a polyolefin, based on the total amount of the spin fluid, and(b) a spin agent, and(ii) flash-spinning the spin fluid at a pressure that is above the vapor pressure of the spin fluid into a region of essentially atmospheric pressure to form plexifilamentary fibrils of the polyolefin;wherein the spin agent comprises an azeotropic or azeotrope-like composition comprising dichloromethane and 1H,4H-octafluorobutane, or wherein the spin agent comprises an azeotropic or azeotrope-like composition comprising dichloromethane and 1-methoxynonafluorobutane, or wherein the spin agent comprises an azeotropic or azeotrope-like composition comprising dichloromethane and 1-ethoxynonafluorobutane.

16. The process of claim 15, wherein the spin fluid comprises from about 76 to about 94 weight percent of the spin agent, based on the total amount of the spin fluid, or from about 80 to about 94 weight percent of the spin agent, based on the total amount of the spin fluid.

17. The process of claim 15 or 16, wherein the polyolefin is selected from the group consisting of polyethylene, polypropylene, polybutene-1, poly(4-methyl-1-pentene), and blends / mixtures thereof.

18. The process of any one of claims 15 to 17, wherein the spin agent comprises an azeotropic or azeotrope-like composition which(1) consists essentially of or consists of from about 32 to about 62 weight percent dichloromethane and from 68 to than about 38 weight percent 1H,4H-octafluorobutane,(2) consists essentially of or consists of from about 46 to about 70 weight percent dichloromethane and from about 54 to about 30 weight percent 1-methoxynonafluorobutane, or(3) consists essentially of or consists of from about 66 to about 85 weight percent dichloromethane and from about 34 to about 15 weight percent 1-ethoxynonafluorobutane.

19. Use of the spin fluid of any one of claims 11 to 14 for preparing of plexifilamentary fibrils of polyolefin by flash spinning.

20. Plexifilamentary fibrils of polyolefin obtainable by the process of any one of claims 15 to 18.

21. A sheet of nonwoven flash-spun plexifilamentary fibrils comprising plexifilamentary fibrils of polyolefin of claim 20.

22. The sheet of claim 21, wherein the sheet is a collected sheet, a consolidated sheet, a bonded sheet, or a softened sheet.

23. An article comprising the plexifilamentary fibrils of polyolefin of claim 20 and / or the sheet of claim 21 or claim 22.

24. The article of claim 23 which is selected from garment, protective apparel, packaging material, house wrap, roof lining, car covers, medical and non-medical packaging, filtration media, print media, tags and labels, and accessories.

Images