Plastomer and elastomer blend compositions

Abstract

A composition of a flexible extrude, wherein the composition includes about 60 to 90 weight percent of a propylene-based elastomer with a density between about 0.857 g / cm3 and 0.902 g / cm3, about 10 to 40 weight percent of an ethylene-based plastomer resin, wherein the total haze percentage as measured by ASTM D1003-A is between 40 percent to 80 percent, and wherein the tensile modulus as measured by ISO 37 is between 8 MPa and 11 MPa.

Description

PLASTOMER AND ELASTOMER BLEND COMPOSITIONSCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Application number 63 / 705,265, filed 9 October 2024, entitled “Plastomer and Elastomer Blend Compositions”, the entirety of which is incorporated by reference herein.FIELD

[0002] Embodiments of the present disclosure generally relate to polymer blends of low density plastomer and amorphous elastomers. In particular, embodiments provided herein relate to compositions of easily recyclable polyolefin blends of propylene-based elastomers and ethylenebased plastomer resins, that may be used for profile extrudates.BACKGROUND

[0003] Certain industrial systems may produce a variety of polymer mixtures, such as copolymers and copolymer mixtures, during operation of the industrial systems. In certain instances, the copolymers may be used in applications such as extrusions, tubing, and general polymer modification. Certain functional attributes (e.g., optical properties, flexibility, mechanical properties, strength, toughness, and compatibilization) are considered important and composition methods and processes need to address obtaining these considerations in a polymer blend. Additionally, environmentally sustainable and economic viable polymer mixtures are needed to move away from use of polyvinyl chloride (PVC) and styrene-ethylene-butylene-styrene (SEBS).SUMMARY

[0004] A summary of certain embodiments disclosed herein is set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of aspects that may not be set forth below.

[0005] In one embodiment, a composition of a flexible extrude, wherein the composition includes about 60 to 90 weight percent of a propylene-based elastomer with a density between about 0.857 g / cm3and 0.902 g / cm3, about 10 to 40 weight percent of an ethylene-based plastomer resin, wherein the total haze percentage as measured by ASTM D1003-A is between 40 percent to 80 percent, and wherein the tensile modulus as measured by ISO 37 is between 8 MPa and 11 MPa.

[0006] In one embodiment a flexible extrudate includes about 60 to 90 weight percent of a propylene-based elastomer, wherein the propylene-based elastomer comprises a density between about 0.857 g / cm3and 0.902 g / cm3, about 10 to 40 weight percent of an ethylene-based plastomer resin, wherein the total haze percentage as measured by ASTM D1003-A is between 40 percent to 80 percent, and wherein the tensile modulus as measured by ISO 37 is between 8 MPa and 11 MPa.

[0007] These and other features and attributes of the present disclosure and their advantageous applications and / or uses will be apparent from the detailed description which follows.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] To assist those of ordinary skill in the relevant art in making and using the subject matter hereof, reference is made to the appended drawings, wherein:

[0009] FIG. 1 is a block diagram of a process for producing a polyolefin blend that may be used to form an extrudates, in accordance with certain embodiments of the present disclosure;

[0010] FIG. 2 is a graph illustrating the haze percentage of a propylene-based elastomer and blends of a propylene-based elastomer, an ethylene-based plastomer resin, and one or more polyolefin blends produced using the techniques of FIG. 1, in accordance with certain embodiments of the present disclosure;

[0011] FIG. 3 is a graph illustrating differential scanning calorimetry (DSC) curves of a propylene-based elastomer, an ethylene-based plastomer resin, and a polyolefin blend produced using the techniques of FIG. 1, in accordance with certain embodiments of the present disclosure;

[0012] FIG. 4 is a graph illustrating differential scanning calorimetry (DSC) curves of a propylene-based elastomer and one or more polyolefin blends of a propylene-based elastomer andone or more ethylene-based plastomer resins, in accordance with certain embodiments of the present disclosure; and

[0013] FIG. 5 is a schematic illustration of a plurality of samples of tubing formed from a neat propylene-based blend and one or more polyolefin blends of a propylene-based elastomer and an ethylene-based plastomer resin, in accordance with certain embodiments of the present disclosure.DETAILED DESCRIPTION

[0014] One or more specific embodiments of the present disclosure will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation- specific decisions must be made to achieve the developers’ specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

[0015] When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. All numerical values within the detailed description herein are modified by “about” the indicated value, and take into account experimental error and variations that would be expected by a person having ordinary skill in the art. For example, “about” or “approximately” may refer to ±0.2%, ±0.5%, ±1%, ±2, ±5%, ±10%, or ±15%.

[0016] For purposes herein a “polymer” has two or more of the same or different monomer (“mer”) units. A “homopolymer” is a polymer having mer units that are the same. A “copolymer” is a polymer having two or more mer units that are different from each other. A “terpolymer” is a polymer having three mer units that are different from each other. “Different” in reference to merunits indicates that the mer units differ from each other by at least one atom or are different isomerically. Accordingly, copolymer, as used herein, can include terpolymers and the like. An "ethylene polymer" or "ethylene copolymer" is a polymer or copolymer comprising at least 50 mole% ethylene derived units, a "propylene polymer" or "propylene copolymer" is a polymer or copolymer comprising at least 50 mole% propylene derived units, and so on.

[0017] As used herein, “Tm” refers to the peak melting point (also referred to as melting point), “Tc” refers to the peak crystallization temperature (also referred to as crystallization temperature), “Tg” refers to the glass transition temperature, “Tonset” refers to onset of melting, “Tend refers to an end of melt based on the last temperate after Tm with an increase of enthalpy higher than 0.1%, “AHF” refers to the enthalpy change during heating, “AHc” refers to the enthalpy change during crystallization determined using the following DSC procedure according to ISO 11357. Data is reported based on the second DSC cycle. A temperature range between -110 °C to 200 °C with a ramp up and a ramp down rate of at 10 °C / min is used . Unless otherwise noted, all temperatures (e.g., Tm, Tc, Tg) are reported in Celsius.

[0018] As used herein, “Tc”, “peak crystallization temperature” or “crystallization temperature,” is the highest temperature peak among principal and secondary crystallization peaks as determined by DSC. For example, the polymer may a single crystallization peak. In some embodiments, the blend may have a secondary crystallization peaks adjacent to the principal peak. The highest of these peaks is considered the peak crystallization temperature. When the crystallinity of the first and the second polymer components is distinguishable, the polymer blend will show two individual peaks for each component. The Tm (e.g., melting temperatures) of the blend may reflect the degree of crystallinity of the crystalline polymer component in the blend. The term “blend” means two or more polymers in which the polymers are blended ex situ, such as by physically or mechanically blending in a mixer, extruder, or other similar device, dispersed and mechanically inseparable blend of two or more polymers produced in situ. In some embodiments, blends may be the result of a polymerization process where a first polymer component is produced in a first reactor and a second polymer component is produced in a second reactor in the presence of the first polymer component. Additionally, and / or alternatively, blends may be produced in a single reactor, a series of reactors, or parallel reactors. Blends may be produced by any suitablepolymerization method, including batch polymerization, semi-continuous polymerization, or continuous polymerization.

[0019] For purposes of this disclosure, a propylene-based polymer having a density of 0.890 g / cm3or less and a random ethylene distribution is referred to as propylene elastomer, propylene- based elastomer, or elastomer. An ethylene-based polymer having a density of more than 0.857 to less than 0.910 g / cm3is referred to as an ethylene-based plastomer resin, an ethylene alpha olefin copolymer, an ethylene plastomer, or plastomer. A high amorphous grade polymer is referred to as a polymer having a density below 0.87 g / cm3. For these definitions, density is determined using the method described in the experimental below.

[0020] A “composition” includes components of the composition and / or reaction products of two or more components of the composition.

[0021] “Pre-cure” refers to before the addition of a curative to the extrusion reactor. For example, pre-cure oil refers to the oil added to the extrusion reactor before the addition of a curative to the extrusion reactor. This pre-cure oil may also be referred to as a first amount of oil. “Postcure” refers to after the addition of a curative to the extrusion reactor.

[0022] All ranges expressed herein should include both end points as two specific embodiments unless specified or indicated to the contrary.

[0023] As mentioned above, industrial systems may produce a variety of polymer blends that may be used to form articles such as tubing, films, sheets, pipes, fibers, and one or more additional extrudates using extrusion processes, co-extrusion processes, blow molding, injection molding, rotary molding, and the like. Based on the desired product, it is generally desirable to control certain functional attributes (e.g., optical properties, flexibility, mechanical properties, strength, toughness, and compatibilization). For example, it may be desirable to form medical tubings that are optically transparent, kink resistant, biocompatible, chemically resistant, flexible, and durable.

[0024] Traditionally, polyvinyl chloride (PVC) resin-based extrudates (e.g., PVC medical grade tubing) are used in medical environments due to optical clarity, chemical resistance and flexibility. However, due to wide spread use of medical tubing and other PVC-based products, it is presently recognized that a sustainable process is desirable for establishing recyclability of medical tubingand other PVC-based products. The presence of chlorine in PVC-based extrudates and products may present challenges for achieving sustainable recycling systems. For example, incineration of PVC-based products including medical grade tubing is known to generate chlorine emissions (e.g., chlorine gas, chlorine-based compounds, hydrochloric acid, chlorinated organic materials, and the like). To comply with certain emission standards, it may be desirable to produce recyclable nonchlorine containing extrudates such as medical grade tubing.

[0025] Accordingly, the present disclosure is directed to techniques for generating a blend (e.g., dry blend, polymer blend) that may be used to form extrudates such as tubing (e.g., tube(s), a piece of tube, and the like), extrudate profiles, films, sheets, pipes, fibers, and the like with certain functional attributes (e.g., optical clarity, flexibility, kink resistance) that may be sustainably recycled via a polyolefin waste stream. In general, the disclosed blends include compositions of propylene-based elastomers and ethylene-based plastomer resins. It is presently recognized that using propylene-based elastomers and ethylene-based plastomer resin blends may provide compositions that may be used to form recyclable extrudates. For example, polyolefin-based articles, substantially free (e.g., containing less than or equal to about 0.1%) of plasticizer additives, may be recycled more readily as compared to traditional plasticizer modified plastics (e.g., SEBS, PVC). As such, the compositions disclosed herein are designed to be polyolefin- based and substantially free of plasticizer additives. The polyolefin-based compositions disclosed herein are designed to form kink resistance, flexible, and optically clear extrudates. Additionally, the present disclosure relates to systems and methods of forming extrudates, extrudate profiles, tubing and / or additional articles using dry blend extrusion. In particular’, it is presently recognized that dry blend extrusion may be advantageous to reduce pre-compounding steps traditionally used to produce PVC-based products.

[0026] Additionally, the disclosed techniques provide compositions with desirable mechanical properties (e.g., processability, dispersion, stability, toughness) and thermal properties (e.g., melting temperature, crystallization temperature), while also having optical clarity, flexibility and kink-resistance. For example, low density plastomers may be combined with high amorphous grade elastomers to generate blends used for extrusion of extrudates. In general, the disclosed blend may include about 60 weight percent (wt%) to 90 wt% of a propylene-based elastomer with a density between about 0.85 g / cm3and 0.90 g / cm3, more preferably between about 0.857 g / cc and0.902 g / cc, and about 10 to 40 wt% of an ethylene-based plastomer resin with a density between about 0.86 and 0.89 g / cm3. The blend may be extruded to form extrudate profiles, tubing, medical grade tubing, and / or one or more additional articles of manufacture. The extrudates generated from the blend may be kink resistance and may demonstrate a total haze percentage between 60 percent to 68 percent.

[0027] Reference is now made to the embodiments illustrated in FIGS. 1-7 wherein like numerals are used to designate like parts throughout.

[0028] With this in mind, FIG. 1 illustrates a block diagram of a process 10 for producing a polyolefin blend 12 that may be used to form one or more extrudates 14, in accordance with certain embodiments of the present disclosure. As shown, the process 10 generally includes receiving, providing, or otherwise obtaining and utilizing a propylene-based elastomer 16 and an ethylenebased plastomer resin 18 to produce the polyolefin blend 12. In some embodiments, the polyolefin blend 12 may be a dry blend of the propylene-based elastomer 16 and the ethylene-based plastomer resin 18, which may reduce pre-compounding steps used in certain conventional processes for producing PVC-based products. Referring to the process 10, at block 20, the propylene-based elastomer 16 and the ethylene-based plastomer resin 18 may be blended and / or combined, thereby producing the polyolefin blend 12. In some embodiments, the polyolefin blend 12 may be produced by mixing the propylene-based elastomer 16, the ethylene-based plastomer resin 18, and, optionally, additives 19 together prior to being put into an extruder. In some embodiments, the propylene-based elastomer 16, and the ethylene-based plastomer resin 18, and the (optional) additives 19 may be mixed directly in an extruder. Additionally, and / or alternatively, the polyolefin blend 12 may be produced by mixing the propylene-based elastomer 16 and the ethylene-based plastomer resin 18 with the (optional) additives 19 in one or more reactors.

[0029] In some embodiments, the polyolefin blend 12 may be produced by mixing the propylene-based elastomer 16 and the ethylene-based plastomer resin 18, and optional additives 19 together. For example, the polyolefin blend 12 may be produced by dry blending the propylene- based elastomer 16, the ethylene-based plastomer resin 18, and the optional additives 19. As referred to herein, “dry blending” refers to a process of mixing solid reagents without solvent or substantially no solvent. In some embodiments, dry blending may include blending powders and / or pellets of the propylene-based elastomer 16, the ethylene-based plastomer resin 18, and oneor more optional additives 19 in a barrel of an extruder. In some embodiments, the extruder may include a single- screw extruder, a twin-screw extruder, a reactive extruder, a Haake extruder, and the like. The powders and / or pellets may be mixed to form a homogenous blend using mechanical forces, such as by turning of screws of a screw extruder (e.g., twin-screw, single-screw). For example, the propylene-based elastomer 16, the ethylene-based plastomer resin 18, and the optional additional additives 19 may be dry blended using a tumbler, a double-cone blender, a ribbon blender, or other suitable blender.

[0030] Alternatively, the powders and / or pellets may be directly mixed prior to introduction into an extrusion process. Additionally, and / or alternatively, the polyolefin blend 12 may be produced by melt mixing the propylene-based elastomer 16 and the ethylene -based plastomer resin 18 together directly in a mixer. As referred to herein, “melt mixing” polymers refers to melting two or more polymers and mixing the two or more polymers when the two or more polymers are in a liquid phase. The mixer may include a static mixer, a batch mixer, and the like. As such, the powders and / or pellets may be contacted in a blender prior to introduction to the extruder. For example, the propylene-based elastomer 16, the ethylene-based plastomer resin 18, and / or optional additional polymers, and optional additional additives 19 may be melt blended in an extruder or batch mixer.

[0031] In some embodiments, the additives 19 may include one or more polymer additives, such as reinforcing and non-reinforcing fillers, scratch resistant agents, antioxidants, heat stabilizers, extender oils, lubricants, antiblocking agents, antistatic agents, anti-fogging agent, waxes, foaming agents, pigments, flame / fire retardants, dyes and colorants and ultraviolet absorber. Other additives 19 include, for example, blowing agents, vulcanizing or curative agents, vulcanizing or curative accelerators, cure retarders, processing aids, tackifying, resins, and other processing aids known in the polymer compounding art. The lists described herein are not intended to be inclusive of all types of additives 19 which may be employed with the present techniques. Upon reading this disclosure, those of skilled in the ait will appreciate other additives 19 may be employed to enhance properties. As is understood by the skilled in the art, the blends of the present techniques may be modified to adjust the characteristics of the blends as desired. The aforementioned additives 19 may be either added independently or incorporated into an additiveor masterbatch. Such additives 19 may comprise up to about 70 wt%, more preferably up to about 65 wt%, of the total composition.

[0032] At block 22, the polyolefin blend 12 may be used to form the extrudates 14 and / or one or more additional components. The extrudates 14 may be formed by extrusion of the polyolefin blend 12. Extrusion may be performed at temperatures and pressures in which the polyolefin blend 12 is in solution. As such, blending may be performed at a temperature greater than the melting point of the propylene-based elastomer 16 and the ethylene-based plastomer resin 18. Extrusion of the polyolefin blend 12 may be used to continuously form the extrudates 14 and / or additional components (e.g., tubing). For example, the extrudates 14 may be formed through extrusion of the polyolefin blend 12 through an annular’ die mounted in-line with the extruder. Size and shape characteristics of the extrudates 14 may be controlled by a sizing process (e.g., sizing die, calibration disc) prior to cooling of the extrudates 14. Additionally, and / or alternatively, the extrudates 14 may be sized using plates and / or rings during cooling of the extrudates 14. In some embodiments, the annular die may be 12 mm by 2 mm with an entrance of 8.5 mm. Further, the sizing process may include an 8.3 mm calibration disc and the extrudates 14 may be cooled in a cooling bath at 30°C. The extrudates 14 may be produced at a haul off rate of about 4 m / min. It should be noted, that this is one non-limiting embodiments, and different annular dies, calibration discs, entrance sizes, cooling temperatures, and haul off rates are envisioned. It should be noted, that alternative components may be formed from the polyolefin blend 12. For example, the polyolefin blend 12 may be extruded to produce tubing, films, coatings, sheets, hollow articles, and the like. As such, extrusion may include blown film extrusion, flat film extrusion, injection moldings, extrusion blow molding, and the like.

[0033] In some embodiments, the polyolefin blend 12 may be produced by blending 60 weight percent (wt%) to 90 wt% of the propylene-based elastomer 16 and about 10 wt% to 40 wt% of the ethylene-based plastomer resin 18. In other embodiments, the propylene-based elastomer 16 may be present in the polyolefin blend 12 from about 65 wt% to 90 wt%, 65 wt% to 85 wt%, 70 wt% to 90 wt%, 70 wt% to 85 wt%, 70 wt% to 80 wt%, or 75 wt% to 80 wt%. The optical clarity of the extrudates 14 may be influenced by the propylene-based elastomer 16 content. In some embodiments, the ethylene-based plastomer resin 18 may be present in the polyolefin blend 12 from about 10 wt% to 35 wt%, 15 wt% to 35 wt%, 20 wt% to 35 wt%, 20 wt% to 30 wt%, 15 wt%to 30 wt%, or 15 wt% to 20 wt%. Without wishing to be bound by theory, it is believed that the flexibility of the extrudates 14 may be influenced by the ethylene-based plastomer resin 18 content. Further, in some embodiments, the relatively low-density of the polyolefin blend 12 may influence the properties of the extrudates 14.

[0034] In some embodiments, the chemical and physical properties (e.g., tensile properties, hardness, thermal behavior, optical properties) of the extrudates 14 may be tuned by the density of the propylene-based elastomer 16 and the ethylene-based plastomer resin 18. It is presently recognized that selecting the propylene-based elastomer 16 and the ethylene-based plastomer resin 18 such that they have certain densities may tune the chemical and physical properties of the extrudates 14. The density of the propylene -based elastomer 16 may range between about 0.86 g / cm3and 0.89 g / cm3, 0.86 and 0.88 g / cm3, or 0.86 and 0.87 g / cm3. Further, the density of the propylene-based elastomer 16 may range between 0.860 and 0.870 g / cm3, 0.862 and 0.869 g / cm3, 0.860 and 0.868 g / cm3, 0.868 and 0.869 g / cm3, or 0.860 and 0.862 g / cm3. The density of the ethylene-based plastomer resin 18 may range between 0.85 and 0.92 g / cm3, between 0.86 and 0.90 g / cm3, between 0.88 and 0.90 g / cm3, between 0.86 and 0.89 g / cm3, between 0.86 and 0.88 g / cm3, or between 0.86 and 0.87 g / cm3. Further, the ethylene-based plastomer resin 18 may range between about 0.865 and 0.900 g / cm3, 0.895 and 0.900 g / cm3, 0.866 and 0.868 g / cm3, 0.868 and 0.872 g / cm3, or 0.868 and 0.870 g / cm3

[0035] Additionally, the tensile properties may be tuned by varying the ratio of the propylene- based elastomer 16 and the ethylene-based plastomer resin 18. Measured tensile properties may include tensile modulus, stress at break, and / or elongation at break. The tensile properties of the extrudates 14 may provide information related to the rigidity, and flexibility (e.g., ductility) of the extrudates 14. The tensile modulus the extrudates 14 may range between 9 to 12 MPa, or 10 to 11 MPa. The stress at break of the extrudates 14 may range between 15 to 19 MPa, or 16 to 18 MPa. The elongation at break the extrudates 14 may range between 850 to 880%, or 870 to 880%.

[0036] The hardness of the extrudates 14 may be tuned by varying the ratio of the propylene- based elastomer 16 and the ethylene-based plastomer resin 18. Measured hardness may include shore hardness measurements. The hardness of the extrudates 14 may provide information related to the deformation and / or resistance to indentation of the extrudates 14. The shore hardness of the extrudates 14 may range between 58 to 62, or 60 to 62. Additionally, the thermal behavior maybe controlled by varying the ratio of the propylene -based elastomer 16 and the ethylene-based plastomer resin 18. Measured thermal behavior of the extrudates 14 may include differential scanning calorimetry (DSC) measurements. The DSC measurements may provide information related to glass transition temperature (Tg), peak melting temperature (Tm), melting enthalpy, peak crystallization temperature, crystallization enthalpy, and the like. The thermal behavior of the extrudates 14 may provide information related to the processability of the polyolefin blend 12, curing behavior of the extrudates 14, and the like.

[0037] The optical properties of the extrudates 14 may be tuned by varying the ratio of the propylene-based elastomer 16 and the ethylene-based plastomer resin 18. Measured optical properties may include haze measurements. Haze measurements measure a degree of scattering of a material as light passes through a sample. It should be noted, that a haze percentage of 0 % is indicative of a material being perfectly clear, that is, that there is no haze present. A haze percentage of 100 % is indicative of a material being perfectly opaque, that is that no light is transmitted through the sample. The optical properties of the extrudates 14 may provide information related to optical clarity and / or optical transparency of the extrudates 14. The haze percentage of the extrudates 14 may range between 50 to 70 %, or 60 to 65 %.

[0038] Table 1 shows a first set of example chemical and physical characteristics of one or more extrudate profiles of the extrudates 14 formed in block 22 of the process 10 of FIG. 1. Measurements were conducted using extrudate profiles with a strip width of approximately 1 mm. In general, Table 1 shows density, melt flow rate (MFR), tensile modulus, stress at break, elongation at break, shore hardness, haze, Tg, TonSet, Tm, Tend, melting enthalpy, peak crystallization temperature, and crystallization enthalpy of the extrudate profile formed by the polyolefin blend 12. Table 1 includes conventional samples of the propylene-based elastomer 16 as illustrated in row 1 and 2 corresponding to Samples Cl and C2. Sample Cl is a neat sample of the propylene- based elastomer 16 of a single density. Sample C2 is a combination of two propylene-based elastomers of different densities. Table 1 also include conventional samples of the ethylene-based plastomer resin 18 corresponding to rows 3 and 4, Samples C3 and C4. As shown, sample C3 has a higher density than Sample C4.

[0039] Additionally, Table 1 includes physical and chemical properties of the extrudate profile formed by various composition of the propylene-based elastomer 16 and the ethylene-basedplastomer resin 18 the propylene-based elastomer 16 represented in rows 5 through 7 of Table 1, wherein Sample El through Sample E3 correspond to examples of the disclosed extrudate profile formed from the polyolefin blend 12. The composition of Sample El is formed through blending approximately 70% of Sample Cl and approximately 30% of Sample C4. Sample E2 is formed through blending approximately 80% of Sample Cl and approximately 20% of Sample C4. Sample E3 is formed through blending approximately 90% of Sample Cl and approximately 10% of Sample C4. Table 1 also includes in row 8, Sample Nl. Sample N1 is a negative example of a composition of the propylcnc-bascd elastomer 16 and an cthylcnc-bascd plastomer resin of a higher density. Sample Nl is formed through blending approximately 80% of Sample Cl and approximately 20% of Sample C3.

[0040] Samples Cl through C4, samples El through E3, and sample Nl were prepared for measurement through Haake extrusion of the propylene-based elastomer 16, the ethylene-based plastomer resin 18, and the polyolefin blend 12. A grating screw with a 3: 1 compression ratio was used with a braker plate during extrusion. During extrusion of the extrudate profile a temperature profile of 200°C to 210°C, a melt temperature between about 197°C and 198°C, a torque between about 20nm to 26nm, a pressure between about 50°C and 55°C, and an output between about 1.3 kg / h and 1.4 kg / h were used.blends

[0041] Table 1 includes the density and MFR of Samples Cl, C3, and C4. The density of Sample Cl is 0.862 g / cm3. The density of Sample C3 is 0.900 g / cm3. The density of Sample C4is 0.868 g / cm3. The melt flow rate (MFR, 2.16 kg weight at 230° C) is measured according to the ASTM D-1238-13. The MFR of Sample Cl is 3.0 g / 10 min. The MFR of Sample C3 is 2.3 g / 10 min. The MFR of Sample C4 is 2.3 g / 10 min.

[0042] Table 1 includes the tensile properties, including tensile modulus, stress at break, elongation at break, as determined according to ISO 37, type 1, using a pull speed of 500 mm / min. A minimum of five specimens from each sample were tested, the results being reported as the average value. All stresses quoted were calculated based upon the original cross-sectional area of the specimen, taking no account of reduced cross-section as a function of increasing strain. Tensile strength is defined as the maximum tensile stress. Table 1 includes the polyolefin blend 12 tensile modulus of approximately between 4.0 and 13.2 MPa. However, it should be noted that the chemical and physical characteristics shown in Table 1 are meant to be non-limiting. For example, the tensile modulus may range between 9.0 to 10.0 MPa, 10.1 to 10.9 MPa, 10.0 to 11.4 MPa, or 10.2 to 11.3 MPa, or approximately 10.5 MPa, approximately 10.7 MPa, approximately 11.4 MPa.

[0043] Table 1 also includes the stress at break of the polyolefin blend 12, approximately between 15.0 and 22.0 MPa. However, it should be noted that the chemical and physical characteristics shown in Table 1 are meant to be non-limiting. For example, the stress at break may range between 15.0 to 20.0 MPa, 16.2 to 19.2 MPa, 16.1 to 18.7 MPa, 17.4 to 18.7 MPa, approximately 17.4 MPa, approximately 16.2 MPa, or approximately 19.0 MPa. Further, Table 1 includes the elongation at break of the polyolefin blend 12, approximately between 783 and 910 %. For example, the elongation at break may range between 861 and 891%, 850 and 890%, 855 and 885%, approximately 876%, approximately 880%, approximately, 886%, or approximately 875% MPa.

[0044] Table 1 also includes the shore hardness of the polyolefin blend 12, approximately between 53 and 63, as determined according to ISO 868, with a test time of 15 seconds. The extrusion profile was plied four times, using a Shore Durometer A device. The shore hardness may range between 59 to 64, 58.6 to 63.8, 53.2 to 63.8, approximately 60, or approximately 61.

[0045] Table 1 includes optical properties of the extrudate profiles formed by the polyolefin blend 12 as determined according to ASTM D1003-A. The optical properties of the extrudates 14 include the haze percentage. It should be noted that the chemical and physical characteristicsshown in Table 1 are meant to be non-limiting. For example, the haze may range between 45 to 68%, 63 to 66%, 60 to 75%, or approximately 65%, approximately 64.8%, or approximately 67%.

[0046] FIG. 2 is a graph 40 illustrating the haze percentage of a propylene-based elastomer and blends of the propylene-based elastomer 16, the ethylene-based plastomer resin 18, and one or more polyolefin blends, in accordance with certain embodiments using the method of FIG. 1. As shown in the graph 40 and included in Table 1 the haze of Samples Cl, C4, and C2 demonstrate that the ratio of the propylene-based elastomer 16 and the ethylene-based plastomer resin 18 in the polyolefin blend 12 may contribute to the haze of tubing. Further, Sample Nl, made of a composition of Samples Cl with a higher density ethylene-based plastomer resin, Sample C3, may increase the haze percentage of the extrudates 14. As such, it may be advantageous to use Sample C4, a lower density ethylene-based plastomer resin, to generate extrudates 14 such as tubing with improved optical clarity.

[0047] Returning to Table 1 , the effect of varying the ratio of the propylene-based elastomer 16 and the ethylene-based plastomer resin 18 of the thermal properties of the extrudate profiles are reported. The thermal properties are measured based on ISO 11357. The thermal properties were reported using the second cycle with a temperature range between -110 °C to 200 °C and a ramp up and a ramp down rate of 10 °C / min. The thermal properties of the extrudate profiles may provide information related to the flexibility and processability of the extrudates 14 and effects of increasing and / or decreasing the amount of the propylene-based elastomer 16. The Tg of the extrudate profiles made from the polyolefin blend 12 may range between about -30 and -32°C. However, it should be noted that the chemical and physical characteristics shown in Table 1 are meant to be non-limiting. For example, Tgmay range between -25 and -32°C, -30.0 and -31.9°C, -30.5 and -31.0°C, -30.5 and -30.9°C, approximately -3O.8°C, approximately -30.7°C, or approximately -32°C. Further, Table 1 includes the Tmof the polyolefin blend 12, approximately between 58 and 106°C. For example, a first Tmpoint may range between 58 and 60°C, approximately 60°C, approximately 59°C, or approximately 59.6°C. A second Tmpoint may range between 105 and 106°C, approximately 105°C, approximately 106°C, or approximately 105.9°C.

[0048] Table 1 also includes the Tend of the polyolefin blend 12. For example, the Tend may range between 114 to 119°C. However, it should be noted that the chemical and physical characteristics shown in Table 1 are meant to be non-limiting. For example, Tend may rangebetween 117.8 and 118.7°C, 117.89 and 118.60°C, 117.8 and 118.5°C, approximately 118.5°C, approximately 119°C, or approximately 118.55°C.

[0049] Table 1 also includes the change in the melting enthalpy (e.g., AHF) of the polyolefin blend 12. For example, the melting enthalpy may range between 6 and 26 J / g. In other nonlimiting embodiments, the melting enthalpy may range between 6 and 12 J / g, 7 and 11 J / g, 9 and 11 J / g, approximately 10 J / g, approximately 11 J / g, or approximately 12 J / g. In some embodiments, the melting enthalpy may range between 6.97 and 12.07 J / g, approximately 6.97 J / g, approximately 10.82 J / g, or approximately 12.04 J / g. Further, Table 1 includes the Tc of the polyolefin blend 12, approximately between 40 and 62°C. For example, a first Tc point may range between 40 and 41 °C, approximately 40.0°C, approximately 41.6°C, approximately 40°C, or approximately 41°C. In some embodiments, the Tc point may range between 39.99 and 40.66°C, approximately 39.99 °C, approximately 40.66°C, or approximately 40.59°C. The change in the crystallization enthalpy (e.g., AHc) of the polyolefin blend 12 may range between 3 and 22 J / g. In other non-limiting embodiments, the crystallization enthalpy may range between 3 and 10 J / g, 4 and 9 J / g, approximately 9 J / g, approximately 10 J / g, or approximately 9.0 J / g. In some embodiments, the crystallization enthalpy may range between 3.70 and 9.77 J / g, 3.70 and 8.96 J / g, approximately 9.77 J / g, approximately 8.96 J / g, or approximately 3.70 J / g.

[0050] FIG. 3 is a graph 60 illustrating differential scanning calorimetry (DSC) curves of the propylene-based elastomer 16, the ethylene-based plastomer resin 18, and a polyolefin blend, in accordance with certain embodiments using the method of FIG. 1. As shown, the graph 60 has a y-axis corresponding to a heat flow (W / g) and an x-axis corresponding to a temperature (°C). During acquisition of the DSC curves a temperature ramp of 10°C per min to 200°C was initiated from an equilibrium temperature of 40°C, followed by a 5 min isothermal, a ramp of 10°C per min to -110°C, a 5 min isothermal, and a temperature ramp of 10°C per min to 200°C.

[0051] FIG. 3 includes various isotherms (e.g., DSC curves) including a Sample Cl isotherm 62, a Sample C4 isotherm 64, and a Sample E2 isotherm 66. The Sample Cl isotherm 62 has a midpoint inflection point 68 corresponding to the Tg of -30.4°C. Additionally, the Sample Cl isotherm 62 has a cold crystallization peak temperature point 70 of 9.3°C. The Sample Cl isotherm 62 has a peak Tm point 72 of 107°C with a normalized melting enthalpy of 3.5 J / g based on an onset at -5.5°C and integration under the curve of the peak Tm point 72.

[0052] The Sample C4 isotherm 64 has a midpoint inflection point 74 corresponding to the Tg of -53.9°C. Additionally, the Sample C4 isotherm 64 has a peak Tm point 76 of 58°C with a normalized melting enthalpy of 53 J / g based on an onset at - 13.4°C and integration under the curve of the peak Tm point 76. The Sample C4 also has a Tc point 78 of 41°C with a crystallization enthalpy of 52.9 J / g based on an onset at 43.9°C and integration under the curve of the peak Tc point 78.

[0053] The Sample E2 isotherm 66 has a midpoint inflection point 80 corresponding to the Tg of -30.8°C. Additionally, the Sample E2 isotherm 66 has a cold crystallization peak temperature point 82 of 8.0°C. Further, Sample E2 isotherm 66 has a first peak Tm point 84 of 59.6°C and a second peak Tm point 86 of 105.9°C with a normalized melting enthalpy of 10.8 J / g based on an onset at 19.9°C and integration under the curve of the first peak Tm 84 and the second peak Tm point 86. The Sample E2 isotherm 66 also has a peak Tc point 88 of 40.6°C with a crystallization enthalpy of 8.9 J / g based on an onset at 43.0°C and integration under the curve of the peak Tc point 88.

[0054] As shown in the graph 60, Sample E2 demonstrates thermal characteristics of both Sample Cl and C4. For example, the peak Tc point 88 of Sample E2 demonstrates characteristics similar’ to Sample C4, indicative that Sample C4 dominates the crystallization character of Sample E2. Similarity of the Tc between Sample C4 and Sample E2 may be indicative of a curing rate of Sample E2 similar to Sample C4. Further the crystallization enthalpy provides insight to heat of cure, with Sample E2 having a lower heat of cure relative to Sample C4. As such, curing behavior of Sample E2 may be dominated by Sample C4. Further, the Tm of Sample E2 is dominated by the Tm of Sample C4. As shown in FIG. 2, the midpoint inflection point 80 corresponding to the Tg point of Sample E2 demonstrates similar- behavior to the midpoint inflection point 68 of Sample Cl. As Tg is a function of molecular weight of the polymer, Sample Cl dominates behavior of the Sample E2. A similar Tg to Sample Cl may lead Sample E2 to have a similar- processability when compared to Sample Cl.

[0055] FIG. 4 is a graph 100 illustrating differential scanning calorimetry (DSC) curves of a propylene-based elastomer and one or more polyolefin blends of a propylene-based elastomer and one or more ethylene-based plastomer resins, in accordance with certain embodiments using the method of FIG. 1. As shown, the graph 100 has a y-axis corresponding to a heat flow (W / g) andan x-axis corresponding to a temperature (°C). During acquisition of the DSC curves a temperature ramp of 10°C per min to 200°C was initiated from an equilibrium temperature of 40°C, followed by a 5 min isothermal, a ramp of 10°C per min to -110°C, a 5 min isothermal, and a temperature ramp of 10°C per min to 200°C.

[0056] FIG. 4 includes various isotherms (e.g., DSC curves) including a Sample Cl isotherm 62, a Sample E2 isotherm 66, and a Sample N1 isotherm 102. The Sample Cl isotherm 62 has a midpoint inflection point 68 corresponding to the Tg of -30.4°C. Additionally, the Sample Cl isotherm 62 has a cold crystallization peak temperature point 70 of 9.3°C. The Sample Cl isotherm 62 has a peak Tm point 72 of 107°C with a normalized melting enthalpy of 3.5 J / g based on an onset at -5.5°C and integration under the curve of the peak Tm point 72.

[0057] The Sample E2 isotherm 66 has a midpoint inflection point 80 corresponding to the Tg of -30.8°C. Additionally, the Sample E2 isotherm 66 has a cold crystallization peak temperature point 82 of 8.0°C. Further, Sample E2 isotherm 66 has a first peak Tm point 84 of 59.6°C and a second peak Tm point 86 of 105.9°C with a normalized melting enthalpy of 10.8 J / g based on an onset at 19.9°C and integration under the curve of the first peak Tm 84 and the second peak Tm point 86. The Sample E2 isotherm 66 also has a peak Tc point 88 of 40.6°C with a crystallization enthalpy of 8.9 J / g based on an onset at 43.0°C and integration under the curve of the peak Tc point 88.

[0058] The Sample N1 isotherm 102 has a midpoint inflection point 104 corresponding to the Tg of -31.5°C. Additionally, the Sample N1 isotherm 102 has a peak Tm point 106 of 91°C with a normalized melting enthalpy of 25.6 J / g based on an onset at 71.1 °C and integration under the curve of the peak Tm 106. The Sample N1 isotherm 102 also has a peak Tc point 108 of 61.1 °C with a crystallization enthalpy of 21.7 J / g based on an onset at 64.5°C and integration under the curve of the peak Tc point 108.

[0059] As shown in the graph 100, the density of the ethylene-based plastomer resin 18 may affect the thermal properties of the polyolefin blend 12. Sample E2 has a lower density ethylenebased plastomer resin than Sample Nl. In general, the density of the ethylene-based plastomer resin 18 within the polyolefin blend 12 used to generate Sample E2 is approximately 0.86 g / cm3while the density of the ethylene-based plastomer resin 18 within the polyolefin blend 12 used togenerate Sample N1 is approximately 0.90 g / cm3. Density of the ethylene-based plastomer resin 18 within the polyolefin blend 12 may affect the Tc peak and the Tm peak. For example, the peak Tc point 108 of Sample N1 is greater than the peak Tc point 88 of Sample E2. Without wishing to be bound by theory, the increase in Tc upon increase of density of the ethylene-based plastomer resin 18 in Sample N1 may produce crystals larger in size when compared to crystals generated at the lower Tc of Sample E2. Larger crystal size may reduce an optical transparency of the extrudates 14 generated from Sample N1 as the larger crystal sizes scatter light more efficiently. Table 1 demonstrates that the haze measurements of Sample N1 arc larger than Sample E2, indicative of reduced optical clarity. As such, it may be advantageous to use the ethylene -based plastomer resin 18 of a lower density when forming the polyolefin blend 12.

[0060] As discussed above, it is presently recognized that selecting a propylene-based elastomer 16 and the ethylene-based plastomer resin 18 such that they have certain densities may provide tuning of certain mechanical and / or physical properties. The extrudates 14 generated from the polyolefin blend 12 may have certain advantageous composition characteristics that may include increased recyclability due to an absence of plasticizer additives. As such, the polyolefin blend 12 disclosed herein may be used to form extrudates 14 with physical characteristics and mechanical characteristics suitable for usage in medical environments. As such, it may be desirable to form the extrudates 14 from the polyolefin blend 12 to generate extrudates 14 with improved flexibility, kink resistance, and optical clarity relative to a comparative propylene-based tubing.

[0061] With this in mind, FIG. 5 is a schematic illustration 120 of a plurality of samples of extrudates 14 in the form of tubing 122 formed from a neat propylene-based blend and one or more polyolefin blends 12 of the propylene-based elastomer 16 and the ethylene -based plastomer resin 18, in accordance with the present disclosure. FIG. 5 illustrates a first tubing 124 generated from neat (e.g., 100%) of the propylene-based elastomer 16, referred herein as Sample Cl, a second tubing 126 generated from a blend or mixture having a ratio of more of the ethylene-based plastomer resin 18 relative to the propylene-based elastomer 16 (e.g., greater than 50%, preferably greater than 75%), and a third tubing 128 generated from a ratio of less of the ethylene-based plastomer resin 18 relative to the propylene-based elastomer 16 (e.g., less than 50%, preferably less than 25%).

[0062] The schematic illustration 120 shows that the first tubing 124 is not flexible, the second tubing 126 is flexible but not kink resistant, and the third tubing 128 is flexible and kink resistant. As described herein, it may be desirable for the extrudates 14 to be flexible, kink resistant, and demonstrate optically clarity. For example, the second tubing 126 is deformed about an inflection point 130. At the inflection point 130, the second tubing 126 generally bends inwards or folds, which may prevent a fluid flows through the deformed tubing. The third tubing 128 curves about an inflection point 132. As such, fluid flows through the curved tubing allowing a flow of fluid about the inflection point 132. Accordingly, the third tubing 128 has a higher degree of kink resistance as compared to the second tubing 126. As shown, the second tubing 126 may include a bend path 134 with a radius of curvature 136. The third tubing 128 may include a bend path 138 with a radius of curvature 140. The radius of curvature 140 of the third tubing 128 is greater than the radius of curvature 136 of the second tubing 126. As such, the flexibility of the third tubing 128 is greater about the point of inflection point 132 as compared to the second tubing 126. The third tubing 128 is representative of tubing extruded using the composition of Sample E2. The third tubing 128 generated through extrusion of Sample E2 is flexible and kink resistant.

[0063] In some embodiments, the third tubing 128 may have a bend diameter 142. The bend diameter 142 may be based on a degree of curvature of the third tubing 128 when a first portion 144 and a second portion 148 of the third tubing 128 are positioned at a fixed distance. In some embodiments, the bend diameter 142 may be less than 100 mm, the bend diameter 142 may range between 30 mm and 60 mm, or 30 and 50 mm. The bend diameter 142 may be approximately 50 mm, approximately 45mm, or approximately 40 mm.

[0064] Without wishing to be bound by theory, physical and chemical properties of the extrudates 14 generated from the polyolefin blend 12 may be influenced by the ratio of the propylene-based elastomer 16 and the ethylene-based plastomer resin 18 content. As such, by varying the amount ratio of the ethylene-based plastomer resin 18 to the propylene-based elastomer 16 as discussed in regards to FIGS. 1 to 3 and Table 1 may provide tuning of the physical and chemical properties of the extrudates 14. In particular, varying the amount of ratio of the ethylenebased plastomer resin 18 to the propylene-based elastomer 16 may produce a tubing 122 having a relatively high kink resistance. As such, the tubing 122 may be used in medical grade applicationswithout the presence of chloride and / or alternative plasticizing agents to improve recyclability and sustainability of the extrudates 14.

[0065] Technical effects of the disclosed embodiments include formation of articles from a polyolefin blend 12 made of a ratio of a propylene-based elastomer 16, an ethylene-based plastomer resin 18, and one or more optional additives 19. Articles formed from the polyolefin blend 12 may include extrudates 14 such as tubing 122 that may be used in the context of medical environments. The extrudates 14 may be formed using dry blending of components of the polyolefin blend 12 and extrusion of the extrudates 14. The extrudates 14 may be flexible, kink resistant, and demonstrate optical clarity. The polyolefin blend 12 may include low density ethylene-based resin to improve flexibility and optical clarity of the extrudates 14. By generating the polyolefin blend 12 for use in production of extrudates 14, overall viability of total recyclability of flexible, kink resistance, and optically clear tubing is improved. The disclosed techniques may result in reduced need for PVC-based tubing. Further, deployment of the presently disclosed techniques may provide improved efficiency of the formation of tubing for widened use across various applications.

[0066] While only certain features of disclosed embodiments have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the present disclosure.

Claims

CLAIMS:

1. A composition of a flexible extrudate, the composition comprising: about 60 to 90 weight percent of a propylene-based elastomer, wherein the propylene-based elastomer comprises a density between about 0.857 g / cm and 0.902 g / cm3; about 10 to 40 weight percent of an ethylene-based plastomer resin; wherein the total haze percentage as measured by ASTM D1003-A is between 40 percent to 80 percent; and wherein the tensile modulus as measured by ISO 37 is between 8 MPa and 11 MPa.

2. The composition of claim 1, wherein the peak crystallization temperature as measure by ISO 11357is between 35°C and 45°C.

3. The composition of claim 1, wherein the density of the ethylene -based plastomer resin is between about 0.860 and 0.890 g / cm3.

4. The composition of claim 1, comprising about 75 to 85 weight percent of the propylene-based elastomer.

5. The composition of claim 4, comprising about 20 weight percent of the ethylene-based plastomer.

6. The composition of claim 1, wherein the melting enthalpy as measured by ISO 11357 is between 8 J / g to 12 J / g.

7. The composition of claim 1 , comprising about 80 weight present of the propylene- based elastomer and approximately 10 to 30 weight percent of the ethylene-based plastomer resin.

8. The composition of claim 1, wherein the density of the propylene-based elastomer is between about 0.860 and 0.870 g / cm3.

9. The composition of claim 1, wherein the flexible extrudate comprises a total haze percentage as measured by ASTM D 1003- A between 60 percent to 68 percent.

10. The composition of claim 1, wherein the flexible extrudate formed from a blend of the propylene-based elastomer and the ethylene-based plastomer resin is kink resistant and optically clear.

11. The composition of claim 1, wherein the composition is a reactor blend or a physical blend.

12. A flexible extrudate, comprising about 60 to 90 weight percent of a propylene -based elastomer, wherein the propylene-based elastomer comprises a density between about 0.857 g / cm3and 0.902 g / cm3; about 10 to 40 weight percent of an ethylene-based plastomer resin; wherein the total haze percentage as measured by ASTM D1003-A is between 40 percent to 80 percent; and wherein the tensile modulus as measured by ISO 37 is between 8 MPa and 11 MPa.

13. The flexible extrudate of claim 12, wherein the extrudate profile comprises a stress at break as measured by ISO 37 between 16 MPa and 22 MPa.

14. The flexible extrudate of claim 12, wherein the extrudate profile comprises an elongation at break as measured by ISO 37 greater than 866 percent.

15. The flexible extradate of claim 12, wherein the extradate profile comprises a shore A hardness as measured by ISO 868 between 58 and 65.

16. The flexible extrudate of claim 12, wherein the extrudate profile comprises a glass transition temperature as measured by ISO 11357 between -25°C and -32°C.

17. The flexible extrudate of claim 12, wherein the extrudate profile is a medical grade tubing.

18. The flexible extrudate of claim 12, comprising a melting enthalpy as measured by ISO 11357 between 8 J / g to 11 J / g.

19. The flexible extrudate of claim 12, comprising a crystallization enthalpy as measured by ISO 11357 between 7 J / g to 12 J / g.

20. The flexible extrudate of claim 12, wherein the density of the ethylene-based plastomer resin is between about 0.860 and 0.890 g / cm3.

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