Low viscosity polypropylene

Abstract

A polypropylene having about 30% and about 80% of all molecules within a molecular weight distribution at a molecular weight of greater than 10,000 g / mole; from about 30.0% to about 84% of all molecules within a molecular weight distribution at a critical molecular weight (Mc) of greater than 10,000 g / mole; and a peak molecular weight ranging from about 10,000 g / mol to about 50,000 g / mol. A homopolymer polypropylene, having (i) between about 30% and about 80% of all molecules within a molecular weight distribution at a molecular weight of greater than 10,000 g / mole; (ii) from about 30.0% to about 84.4% of all molecules within a molecular weight distribution at a critical molecular weight (Mc) of greater than 10,000 g / mole; and (iii) an isotactic pentad fraction of equal to or greater than about 94.0 mole% as measured by nuclear magnetic resonance (NMR).

Description

LOW VISCOSITY POLYPROPYLENECROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims benefit and priority of U.S. provisional patent application Serial No 63 / 702,028 filed on October 1 ,2024, and entitled “LOW VISCOSITY POLYPROPYLENE,” which is hereby incorporated herein by reference in its entirety for all purposes.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] Not applicable.TECHNICAL FIELD

[0003] The present disclosure relates generally to polymer compositions. More particularly, the present disclosure relates to polypropylene compositions having improved performance characteristics.BACKGROUND

[0004] Low viscosity polypropylene’s (LVPP), having melt flow rates greater than 100 dg / min, primary use is in melt blown applications. Beyond commercial melt blown polypropylene, there is another common application for low viscosity polypropylene, as polypropylene wax. The dividing line between conventional polypropylene and polypropylene wax is not sharply demarcated within the technical literature. However, the demarcation between these polypropylenes is believed to be substantially based on factors such as testing standards and material form.

[0005] It is contemplated that the technical dividing line may tie back to entanglement molecular weight. Herein the entanglement molecular weight is based on the observation that, for the most part, plastics have moderate to low chain persistence (chain rigidity). However, plastics typically display sufficient flexibility such that at some point in increasing molecular weight, different chains can physically interact with each other so that a mechanical stress can be transferred from one chain to another. The structural conformation that leads to the transfer of mechanical stress from one chain to another is termed an entanglement and the molecular weight at which this structural conformation occurs is termed the molecular weight of entanglement (Me). Polypropylene (PP) has an Meof approximately 4650 g / mol.

[0006] For an individual molecule chain to contribute to bulk physical properties of the polymer (e.g., tensile strength) the molecule chain should have a molecular weight of greater than or equal to 2 times Me, which is commonly called the critical molecular weight (Mc). The Mcrefers to the minimum molecular weight at which the polymer chains begin to significantly entangle with each other, leading to a noticeable change in its physical properties like increased viscosity, altered mechanical behavior. Essentially, the Mcindicates the point where the polymer starts to exhibit characteristics associated with a higher molecular weight than expected for a given number average molecular weight due to chain entanglement.

[0007] For simplicity, polypropylene’s Mccan be rounded up to 10,000 g / mol. Consequently, with greater than 2x Meas the technical foundation a polypropylene wax would comprise having greater than about 50% species with a molecular weight less than or equal to 10,000 g / mol. A conventional polypropylene, such as those used in melt blown applications, would comprise having equal to or greater than about 50% species with a molecular weight greater than 10,000 g / mol.

[0008] The benefits of a LVPP having greater than about 50% species with a molecular weight less than or equal to 10,000 g / mol could include increased process throughput and, reduced processing pressures. Consequently, it is of technical and commercial interest to develop new catalysts, processes, and / or technologies for manufacturing such low viscosity polypropylenes.SUMMARY

[0009] Disclosed herein is a polypropylene having about 30% and about 80% of all molecules within a molecular weight distribution at a molecular weight of greater than 10,000 g / mole; from about 30.0% to about 84% of all molecules within a molecular weight distribution at a critical molecular weight (Mc) of greater than 10,000 g / mole; and a peak molecular weight ranging from about 10,000 g / mol to about 50,000 g / mol.

[0010] Also disclosed herein is a homopolymer polypropylene, having (i) between about 30% and about 80% of all molecules within a molecular weight distribution at a molecular weight of greater than 10,000 g / mole; (ii) from about 30.0% to about 84.4% of all molecules within a molecular weight distribution at a critical molecular weight (Mc) of greater than 10,000 g / mole; and (iii) an isotactic pentad fraction of equal to or greater than about 94.0 mole% as measured by nuclear magnetic resonance (NMR).

[0011] Also disclosed herein is a rheology modifier comprising, a polypropylene having (i) from about 30% to about 80% of all molecules within a molecular weight distribution at a molecular weight of greater than 10,000 g / mole; (ii) from about 30.0% to about 84.4% of all molecules within a molecular weight distribution at a critical molecular weight (Me) of greater than 10,000 g / mole; and (iii) a peak molecular weight ranging from about 10,000 g / mol to about 50,000 g / mol.

[0012] Also disclosed herein is a meltbown fabric comprising a polypropylene having (i) from about 30% to about 80% of all molecules within a molecular weight distribution at a molecular weight of greater than about 10,000 g / mole; (ii) from about 30.0% to about 84.4% of all molecules within a molecular weight distribution at a critical molecular weight (Me) of greater than 10,000 g / mole; and (iii) a peak molecular weight ranging from about 10,000 g / mol to about 50,000 g / mol.

[0013] Also disclosed herein is a hot melt adhesive comprising, a polypropylene having (i) from about 30% to about 80% of all molecules within a molecular weight distribution at a molecular weight of greater than 10,000 g / mole; (ii) from about 30.0% to about 84.4% of all molecules within a molecular weight distribution at a critical molecular weight (Me) of greater than 10,000 g / mole; and (iii) a peak molecular weight ranging from about 10,000 g / mol to about 50,000 g / mol.

[0014] Also disclosed herein is polypropylene having a plurality of polymer populations wherein (i) at least one population has molecular chains with a Mw of less than 10,000 g / mol and present in an amount of equal to or greater than about 50% of the total polymer population; (ii) another population having molecular chains with a Mw of less than 1 ,000 g / mol present in an amount of equal to or greater than about 5% of the total polymer population wherein the polypropylene displays a peak molecular weight ranging from about 10,000 g / mol to about 50,000 g / mol.

[0015] Aspects described herein comprise a combination of features and characteristics intended to address various shortcomings associated with certain prior devices, systems, and methods. The foregoing has outlined rather broadly the features and technical characteristics of the disclosed aspects in order that the detailed description that follows may be better understood. The various characteristics and features described above, as well as others, will be readily apparent to those skilled in the art upon reading the following detailed description, and by referring to the accompanying drawings. It should be appreciated that the conception and the specific aspects disclosed may be readily utilized as a basis for modifying or designing otherstructures for carrying out the same purposes as the disclosed aspects. It should also be realized that such equivalent constructions do not depart from the spirit and scope of the principles disclosed herein.DETAILED DESCRIPTION

[0016] The following discussion is directed to various exemplary aspects. However, one skilled in the art will understand that the examples disclosed herein have broad application, and that the discussion of any aspect is meant only to be exemplary of that aspect, and not intended to suggest that the scope of the disclosure, including the claims, is limited to that aspect.

[0017] Certain terms are used throughout the following description and claims to refer to particular features or components. As one skilled in the art will appreciate, different persons may refer to the same feature or component by different names. This document does not intend to distinguish between components or features that differ in name but not function. The drawing figures are not necessarily to scale. Certain features and components herein may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in interest of clarity and conciseness.

[0018] Unless the context dictates the contrary, all ranges set forth herein should be interpreted as being inclusive of their endpoints, and open-ended ranges should be interpreted to include only commercially practical values. In addition, with respect to all ranges disclosed herein, such ranges are intended to include any combination of the mentioned upper and lower limits even if the particular combination is not specifically listed. All lists of values should be considered as inclusive of intermediate values unless the context indicates the contrary. Where numerical ranges or limitations are expressly stated, such express ranges or limitations should be understood to include iterative ranges or limitations of like magnitude falling within the expressly stated ranges or limitations (e.g., from about 1 to about 10 includes, 2, 3, 4, etc.; greater than 0.10 includes 0.11 , 0.12, 0.13, etc.).

[0019] In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to... .” As used herein, the phrases “consist(s) of” and “consisting of” are used to refer to exclusive components of a composition, meaning only those expressly recited components are included in the composition; whereas thephrases “consist(s) essentially of” and “consisting essentially of” are used to refer to the primary components of a composition, meaning that only small or trace amounts of components other than the expressly recited components (e.g., impurities, byproducts, etc.) may be included in the composition. For example, a composition consisting of X and Y refers to a composition that only includes X and Y, and thus, does not include any other components; and a composition consisting essentially of X and Y refers to a composition that primarily comprises X and Y, but may include small or trace amounts of components other than X and Y. In aspects described herein any such small or trace amounts of components other than those expressly recited following the phrase “consist (s) essentially of” or “consisting essentially of” preferably represent less than 5.0 wt.% of the composition, more preferably less than 4.0 wt.% of the composition even more preferably less than 3.0 wt.% of the composition, and still more preferably less than 1 .0 wt.% of the composition. Use of broader terms such as comprises, includes, having, etc. should be understood to provide support for narrower terms such as consisting of, consisting essentially of, comprised substantially of, etc. Use of the term "optionally" with respect to any element of a claim is intended to mean that the subject element is required, or additionally or alternatively , is not required. Both alternatives are intended to be within the scope of the claim. As used herein, the terms “approximately,” “about,” “substantially,” and the like mean within 10% (i.e., plus or minus 10%) of the recited value. Thus, for example, a recited angle of “about 80 degrees” refers to an angle ranging from 72 degrees to 88 degrees.

[0020] Disclosed herein are low viscosity polypropylene compositions characterized by a novel polymer architecture, Polymer architecture is a term that captures the molecular features of the bulk polymer. Molecular features of the bulk polymer include, but are not limited to, molecular weight distribution, tacticity, comonomer (if present) and how the comonomer (if present) is incorporated within the polymer chain. It is a term that is used to holistically capture how the monomers are polymerized together to from the bulk polymer.

[0021] In one or more aspects, the low viscosity polypropylene compositions disclosed herein are characterized by the presence equal to or greater than about 50% of the molecular chains having a weight average molecular weight (Mw) of less than about 10,000 g / mol. The low viscosity polypropylene compositions may have a plurality ofmolecular chain populations n where each population is characterized by (i) an upper limit of the Mwand (ii) the percentage of molecular chains having the upper limit of Mw.

[0022] In one or more aspects, the low viscosity polypropylene is characterized by the presence of a first population (P1 ) having molecular chains with a Mwof less than about 10,000 g / mol and a second population (P2) having molecular chains with a Mwof less than about 1000 g / mol. In such aspects, the low viscosity polypropylene comprises equal to or greater than about 50% of P1 and at least about 5% of P2. In other aspects, the low viscosity polypropylene comprises equal to or greater than about 50% of P1 and at least about 5%, or at least about 7.5%, or at least about 10% or at least about 12.5% or at least about 15% or at least about 20% of P2. It is contemplated that the low viscosity polypropylene may be characterized by the presence of 2 or more molecular chain populations, alternatively 3 or more molecular chain populations or alternatively 4 or more molecular chain populations. However, the remainder of the disclosure will refer to low viscosity polypropylene having a single population (P1 ) where equal to or greater than about 50% of the molecular chains have a Mwof less than about 10,000 g / mol designated LVPPi .

[0023] An LVPPi of the present disclosure may be described further by (i) molecular weight characteristics; (ii) melt behavior; (iii) percent crystallinity; (iv) isotacticity; (v) flexural modulus; (vi) zero shear viscosity or combinations of (i) through (vi). In one or more aspects, the LVPPi is a homopolymer polypropylene, an isotactic polypropylene or an isotactic homopolymer polypropylene. The expression "propylene homopolymer" refers to a polypropylene that consists substantially of propylene units (e.g., greater than about 95%). Herein the term “isotactic” refers to all the substituents on the polypropylene (methyl groups) being located on the same side of the macromolecular backbone.

[0024] Polymer molecular weight may be described utilizing parameters such as The number-average molecular weight (Mn) , weight average molecular weight (Mw), Z- average molecular weight (Mz) and peak weight (Mp) which can be determined using any suitable methodology such as gel permeation chromatography (GPC). For example, Mnis the number-average molecular weight of the individual polymers and is calculated by measuring the molecular weight M, of A / , polymer molecules, summing the weights g / mol, and dividing by the total number of polymer molecules, according to equation 1 :wherein Ni is the number of molecules of molecular weight Mi. In one or more aspects, GPC is used to determine the molecular weight characteristics of an LVPPi. GPC may be carried out using a Polymer Char GPC-IR equipped with three columns. Analysis of the elutriate were via an infrared detector. Polystyrene standards may be used for column calibration.

[0025] In one or more aspects, an LVPPi is characterized by having between about 30% and about 80% of all molecules within a molecular weight distribution at a molecular weight of greater than 10,000 g / mole, where the full molecular weight distribution counts all species with a molecular weight greater than 1000 g / mole. In one or more aspects, the LVPPi has between about 30.0% and about 84.4% of all molecules within a molecular weight distribution at a critical molecular weight (Mc) of greater than 10,000 g / mole, alternatively between about 74.4% and about 84.4%, alternatively between about 50% and about 74.4%, alternatively between about 76% and about 84.4%, alternatively between about 76% and about 82.4%, alternatively between about 76% and about 80.6%. In one or more aspects, the LVPPi has 30%, about 31 %, about 32%, about 33%, about 34%, about 35%, about 36%, about 37%, about 38%, about 39%, about 40%, about 41 %, about 42%, about 43%, about 44%, about 45%, about 46%, about 47%, about 48%, about 49%, about 50%, about 51 %, about 52%, about 53%, about 54%, about 55%, about 56%, about 57%, about 58%, about 59%, about 60%, about 61 %, about 62%, about 63%, about 64%, about 65%, about 66%, about 67%, about 68%, about 69%, about 70%, about 71 %, about 72%, about 73%, about 74%, about 75%, about 76%, about 77%, about 78%, about 79%, about 80%, about 81 %, about 82%, about 83%, about 84%, about 85%, about 86%, about 87%, about 88%, about 89%, about or about 90% of all molecules at a molecular weight of greater than about 10,000 g / mole, where the full molecular weight distribution counts all species with a molecular weight greater than 1000 g / mol.

[0026] The LVPPi may be characterized by a peak molecular weight (Mp) ranging from about 10,000 g / mol to about 50,000 g / mol, alternatively from about 10, 000 g / mol to about 45,900 g / mol, alternatively from about 10,000 g / mol to about 45,000g / mol, alternatively from about 25,200 g / mol to about 45,900 g / mol, alternatively from about30,000 g / mole to about 45,900 g / mol, alternatively from about 30,000 g / mol to about43,100 g / mol, alternatively from about 31 ,400 g / mol to about 40,500 g / mol, alternatively about 10,000 g / mol, 10,200 g / mol, 10,400 g / mol, 10,600 g / mol, 10,800 g / mol, 11 ,000 g / mol, 11 ,200 g / mol, 11 ,400 g / mol, 11 ,600 g / mol, 11 ,800 g / mol, 12,000 g / mol, 12,200g / mol, 12,400g / mol, 12,600g / mol, 12,800g / mol, 13,000g / mol,13,200g / mol, 13,400g / mol, 13,600g / mol, 13,800g / mol, 14,000g / mol, 14,200g / mol 14,400g / mol, 14,600g / mol, 14,800g / mol, 15,000g / mol, 15,200g / mol, 15,400g / mol 15,600g / mol, 15,800g / mol, 16,000g / mol, 16,200g / mol, 16,400g / mol, 16,600g / mol 16,800g / mol, 17,000g / mol, 17,200g / mol, 17,400g / mol, 17,600g / mol, 17,800g / mol 18,000g / mol, 18,200g / mol, 18,400g / mol, 18,600g / mol, 18,800g / mol, 19,000g / mol 19,200g / mol, 19,400g / mol, 19,600g / mol, 19,800g / mol, 20,000g / mol, 20,200g / mol 20,400g / mol, 20,600g / mol, 20,800g / mol, 21 ,000g / mol, 21 ,200g / mol, 21 ,400g / mol 21 ,600g / mol, 21 ,800g / mol, 22,000g / mol, 22,200g / mol, 22,400g / mol, 22,600g / mol 22,800g / mol, 23,000g / mol, 23,200g / mol, 23,400g / mol, 23,600g / mol, 23,800g / mol 24,000g / mol, 24,200g / mol, 24,400g / mol, 24,600g / mol, 24,800g / mol, 25,000g / mol 25,200g / mol, 25,400g / mol, 25,600g / mol, 25,800g / mol, 26,000g / mol, 26,200g / mol 26,400g / mol, 26,600g / mol, 26,800g / mol, 27,000g / mol, 27,200g / mol, 27,400g / mol 27,600g / mol, 27,800g / mol, 28,000g / mol, 28,200g / mol, 28,400g / mol, 28,600g / mol 28,800g / mol, 29,000g / mol, 29,200g / mol, 29,400g / mol, 29,600g / mol, 29,800g / mol 30,000g / mol, 30,200g / mol, 30,400g / mol, 30,600g / mol, 30,800g / mol, 31 ,000g / mol 31 ,200g / mol, 31 ,400g / mol, 31 ,600g / mol, 31 ,800g / mol, 32,000g / mol, 32,200g / mol 32,400g / mol, 32,600g / mol, 32,800g / mol, 33,000g / mol, 33,200g / mol, 33,400g / mol 33,600g / mol, 33,800g / mol, 34,000g / mol, 34,200g / mol, 34,400g / mol, 34,600g / mol 34,800g / mol, 35,000g / mol, 35,200g / mol, 35,400g / mol, 35,600g / mol, 35,800g / mol 36,000g / mol, 36,200g / mol, 36,400g / mol, 36,600g / mol, 36,800g / mol, 37,000g / mol 37,200g / mol, 37,400g / mol, 37,600g / mol, 37,800g / mol, 38,000g / mol, 38,200g / mol 38,400g / mol, 38,600g / mol, 38,800g / mol, 39,000g / mol, 39,200g / mol, 39,400g / mol 39,600g / mol, 39,800g / mol, 40,000g / mol, 40,200g / mol, 40,400g / mol, 40,600g / mol 40,800g / mol, 41 ,000g / mol, 41 ,200g / mol, 41 ,400g / mol, 41 ,600g / mol, 41 ,800g / mol 42,000g / mol, 42,200g / mol, 42,400g / mol, 42,600g / mol, 42,800g / mol, 43,000g / mol 43,200g / mol, 43,400g / mol, 43,600g / mol, 43,800g / mol, 44,000g / mol, 44,200g / mol 44,400g / mol, 44,600g / mol, 44,800g / mol, 45,000g / mol, 45,200g / mol, 45,400g / mol 45,600g / mol, 45,800g / mol, 46,000g / mol, 46,200g / mol, 46,400g / mol, 46,600g / mol 46,800g / mol, 47,000g / mol, 47,200g / mol, 47,400g / mol, 47,600g / mol, 47,800g / mol48,000g / mol, 48,200g / mol, 48,400g / mol, 48,600g / mol, 48,800g / mol, 49,000g / mol, 49,200g / mol, 49,400g / mol, 49,600g / mol, 49,800g / mol, or 50,000g / mol. The peak molecular weight Mp, refers to the molecular weight of the highest peak. The Mpof a polymer is the molecular weight at the peak of the distribution curve. The width of the peak indicates the width of the molecular weight distribution. A narrow peak indicates a narrow distribution, while a wide peak indicates a wide distribution. Therefore, Mpis the mode of the molecular weight distribution.

[0027] In one or more aspects, the LVPPi is characterized by a polydispersity index ranging from greater than about 2.5 to about 10; additionally or alternatively from about 3 to about 10; additionally or alternatively from about 4 to about 10. The polydispersity index refers to a ratio of the Mwto the number average molecular weight Mnor Mw / Mn.

[0028] In alternative aspects, the polydispersity index ranges from about 3.0 to about9.5, alternatively from about 4.0 to about 8.5, alternatively from about 4.5 to about 8.0 alternatively from about 5.0 to about 7.5, alternatively from about 2.5 to about 8.5, alternatively from about 2.5 to about 7.0 or alternatively about 2.6, about 2.7, about 2.8, about 2.9, about 3, about 3.1 , about 3.2, about 3.3, about 3.4, about 3.5, about3.6, about 3.7, about 3.8, about 3.9, about 4, about 4.1 , about 4.2, about 4.3, about4.4, about 4.5, about 4.6, about 4.7, about 4.8, about 4.9, about 5, about 5.1 , about5.35, about 5.6, about 5.85, about 6.1 , about 6.35, about 6.6, about 6.85, about 7.1 , about 7.35, about 7.6, about 7.85, about 8.1 , about 8.35, about 8.6, about 8.85, about9.1 , about 9.35, about 9.6, about 9.85, or about 10.0.

[0029] In one or more aspects, the LVPPi comprises three discrete melting peaks, alternatively two discrete melting peaks or alternatively one discrete melting peak. In one or more aspects, the LVPPi has at least two melting peaks or alternatively at least three melting peaks which can be designated x and y if there are two peaks or x, y and z if there are three peaks. In such aspects, the value of x (the lowest peak melting temperature) is less than the value of y which is less than the value of z. In one or more aspects, x is equal to or greater than about 100°C. In such aspects, x, y or z may have values equal to greater than about 100°C, or alternatively about 101 °C, about 102°C, about 103°C, about 104°C, about 105°C, about 106°C, about 107°C, about108°C, about 109°C, about 110°C, about 111 °C, about 1 12°C, about 113°C, about114°C, about 115°C, about 116°C, about 117°C, about 1 18°C, about 119°C, about120°C, about 121 °C, about 122°C, about 123°C, about 124°C, about 125°C, about126°C, about 127°C, about 128°C, about 129°C, about 130°C, about 131 °C, about132°C, about 133°C, about 134°C, about 135°C, about 136°C, about 137°C, about138°C, about 139°C, about 140°C, about 141 °C, about 142°C, about 143°C, about144°C, about 145°C, about 146°C, about 147°C, about 148°C, about 149°C, about150°C, about 151 °C, about 152°C, about 153°C, about 154°C, about 155°C, about156°C, about 157°C, about 158°C, about 159°C, about 160°C, about 161 °C, about162°C, about 163°C, about 164°C, about 165°C, about 166°C, about 167°C, about168°C, about 169°C, about 170°C, about 171 °C, about 172°C, about 173°C, about174°C, about 175°C, about 176°C, about 177°C, about 178°C, about 179°C, about180°C, about 181 °C, about 182°C, about 183°C, about 184°C, about 185°C, or about 186 °C.

[0030] In one or more aspects, the LVPPi has at least two melting peaks one designated a primary peak with a melting temperature of equal to or greater than about 148 °C. The second peak which occurs at a higher temperature than the primary peak is designated the endset melting temperature which may be at a temperature of equal to or greater than about 155°C g / mol. For example, the primary peak melting temperature may be about 148 °C, 148.5°C g / mol, 149°, 149.5 °C ,150 °C , 150.5 °C, 151 °C , 151.5 °C, 152 °C ,152.5 °C ,153 °C ,153.5 °C ,154 °C ,154.5 °C .while the endset melting temperature may be about 155 °C , 155.5 °C , 156 °C , 156.5 °C , 157 °C ,157.5 °C ,158 °C ,158.5 °C , 159 °C ,159.5 °C ,160 °C ,160.5 °C ,161 °C ,161.5 °C ,162 °C ,162.5 °C ,163 °C ,163.5 °C ,164 °C ,164.5 °C ,165 °C ,165.5 °C ,166 °C ,166.5 °C ,167 °C ,167.5 °C , 168 °C ,168.5 °C ,169 °C ,169.5 °C ,170 °C ,170.5 °C ,171 °C ,171.5 °C ,172 °C ,172.5 °C ,173 °C ,173.5 °C ,174 °C ,174.5 °C ,175 °C ,175.5 °C ,176 °C ,176.5 °C , 177 °C ,177.5 °C ,178 °C ,178.5 °C, 179 °C ,179.50C ,180 °C , 180.5 °C ,181 °C ,181.5 °C ,182 °C ,182.5 °C , or 183 °C .

[0031] In one or more aspects, the LVPPi is characterized by a lowest melting temperature of equal to or greater than about 100°C or equal to or greater than about 115°C or equal to or greaterthan about 183°C. The LVPPi may have a highest melting temperature of equal to or greater than about 183°C. In one or more aspects, the LVPPi is characterized by a lowest peak Tmof equal to or greater than about 120°C. In such aspects all melting peaks may occur in temperatures ranging from about 100°C to about 183°C. In an alternative aspect, Tmis equal to or greater than about 130°C. In yet other aspects, Tmis equal to or greater than about 145°C. In such aspects all melting peaks may occur in temperatures between about 120°C and about 183°C.

[0032] In one or more aspects, the LVPPi has a percent crystallinity of equal to or greater than about 10% or alternatively equal to greater than about 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%. The percent crystallinity refers to the overall level of crystalline component in relationship to its amorphous component. The percent crystallinity is directly related to polymer properties such as brittleness, toughness, modulus, optical clarity, cold flow, long term stability and barrier resistance.

[0033] In one or more aspects, the LVPP1 is characterized by an isotactic pentad fraction (denoted mmmm) of equal to or greater than about 94.0% as measured by nuclear magnetic resonance (NMR). Herein the isotactic pentad fraction refers to a pentad polymer unit where each pair of methyl groups in the pentad has the same stereochemical configuration. In one or more aspects, the polypropylene has an isotactic pentad fraction of equal to or greater than about 94%, or equal to or greater than about 94.5%, or equal to or greater than about 95%, or equal to or greater than about 95.5%, or equal to or greater than about 96%, or equal to or greater than about 96.5%, or equal to or greater than about 97%, or equal to or greater than about 97.5%, or equal to or greater than about 98%, or equal to or greater than about 98.5%, or equal to or greater than about 99% or equal to or greater than about 99.5%. In one or more aspects, the LVPPi has a flexural modulus of from about 25 kilopound-force per square inch (kpsi) to about 400 kpsi, alternatively from about 50 kpsi to about 400 kpsi, alternatively about 50 kpsi to about 375 kpsi, alternatively about 75 kpsi to about 400 kpsi, alternatively about 75 kpsi to about 375 kpsi, alternatively about 100 kpsi to about 400 kpsi, alternatively about 100 kpsi to about 375 kpsi, alternatively about 200 kpsi to about 350 kpsi , alternatively about 150 kpsi to about 300 kpsi or about 25 kpsi, about 50 kpsi, about 75 kpsi, about 100 kpsi, about 125 kpsi, about 150 kpsi, about 175 kpsi, about 200 kpsi, about 225 kpsi, about 250 kpsi, about 275 kpsi, about 300 kpsi, about 325 kpsi, about 350 kpsi, about 375 kpsi, pr about 400 kpsi. The flexural modulus refers to the ability of a material to bend without deformation and may be determined in accordance with ASTM D790.

[0034] In one or more aspects, the LVPPi has a zero-shear viscosity between about 0.001 Pascal-seconds (Pa-s) to 100 Pascal-seconds at 190°C. The zero-shear viscosity (often called zero-shear rate viscosity) is a descriptor of the flow resistance of polymer melts and solutions, The zero-shear viscosity can be defined as a limiting value of viscosity or the viscosity of the material at rest. In one or more aspects, theLVPPi has a zero-shear viscosity at 190°C of from 0.01 Pa-s to about 100 Pa-s, alternatively about 0.1 Pa-s to about 100 Pa-s, alternatively about 1 Pa-s to about 100 Pa-s, alternatively about 5 Pa-s to about 100 Pa-s, alternatively about 10 Pa-s to about 100 Pa-s, alternatively about 20 Pa-s to about 100 Pa-s, alternatively about 30 Pa-s to about 100 Pa-s, alternatively about 45 Pa-s to about 100 Pa-s, alternatively about 50 Pa-s to about 100 Pa-s, alternatively about 80 Pa-s to about 100 Pa-s or alternatively about 0.001 Pa-s, about 0.003 Pa-s, about 0.006 Pa-s, about 0.01 OPa-s, about 0.03Pa-s, about 1 Pa-s, about 3 Pa-s, about 10 Pa-s, about 25 Pa-s, about 40 Pa-s, about 45 Pa-s, about 55 Pa-s, about 60 Pa-s, about 75 Pa-s, about 80 Pa-s, or about 100 Pa-s.

[0035] In an aspect, a method of the present disclosure comprises polymerization processes where a monomer (such as propylene), and, an optional comonomer, are introduced to (or contacted with) a catalyst system (e.g., metallocene catalyst) under conditions suitable for the formation of a LVPPi . Metallocene catalysts may be characterized generally as coordination compounds incorporating one or more cyclopentadienyl (Op) groups (which may be substituted or unsubstituted, each substitution being the same or different) coordinated with a transition metal through bonding. The substituent groups on Cp may be linear, branched or cyclic hydrocarbyl radicals, for example. The inclusion of cyclic hydrocarbyl radicals may transform the Cp into other contiguous ring structures, such as indenyl, azulenyl and fluorenyl groups, for example. These contiguous ring structures may also be substituted or unsubstituted by hydrocarbyl radicals, such as Ci to C20 hydrocarbyl radicals, for example. A specific, non-limiting, example of a metallocene catalyst is a bulky ligand metallocene compound generally represented by the formula:[LJmM]Aln; where L is a bulky ligand, A is a leaving group, M is a transition metal, R is a halogen, an alkoxy, or a hydrocarboxyl group and x is the valence of the transition metal. For example, x may be from 1 to 4.

[0036] The metal atom "M" of the metallocene catalyst compound may be selected from Groups 3 through 12 atoms and lanthanide Group atoms, or from Groups 3 through 10 atoms or from Sc, Ti, Zr, Hf, V, Nb, Ta, Mn, Re, Fe, Ru, Os, Co, Rh, Ir and Ni. The oxidation state of the metal atom "M" may range from 0 to +7 or is +1 , +2, +3, +4 or +5, for example. The bulky ligand generally includes a cyclopentadienyl group (Cp) or a derivative thereof The Cp ligands are distinct from the leaving groups boundto the catalyst compound in that they are not highly susceptible to substitution / abstraction reactions. Cp ligands may include ring(s) or ring system(s) including atoms selected from group 13 to 16 atoms, such as carbon, nitrogen, oxygen, silicon, sulfur, phosphorous, germanium, boron, aluminum and combinations thereof.

[0037] In one or more aspects, a catalyst composition for use in the present disclosure comprises a differentiated metallocene catalyst, a titanated solid oxide support; at least one optional activator; and at least one optional co-catalyst.

[0038] Exemplary optional comonomers may include ethylene, butene, pentene, hexene, heptene, octene, nonene, decene, undecene, dodecene, norbornene, ethylidenenorbornene, vinylnorbornene, norbomadiene, dicyclopentadiene, cyclopentene, cycloheptene, cyclooctene, cyclooctadiene cyclododecene, 7- oxanorbornene, 7-oxanorbornadiene, substituted derivatives thereof, and isomers thereof, such as hexene, heptene, octene, nonene, decene, dodecene, cyclooctene, 5-cyclooctadiene, 1 -hydroxy-4-cyclooctene, 1-acetoxy~4-cyclooctene, 5- methylcyclopentene, cyclopentene, dicyclopentadiene, norbornene, norbomadiene, butadiene, hexadiene, heptadiene, octadiene, nonadiene, decadiene, undecadiene, dodecadiene, and their respective homologs and derivatives, such as norbornene, norbomadiene, and dicyclopentadiene.

[0039] Polymerization processes of this present disclosure can be carried out in any suitable technology. Any suspension, bulk, slurry, or gas phase polymerization process known in the art can be used. Such processes can be run in a batch, semibatch, or continuous mode. Homogeneous polymerization processes and slurry processes can be employed. A homogeneous polymerization process refers to a process where at least 90 weight percent (wt.%) of the product is soluble in the reaction media. A homogeneous polymerization process can be a bulk homogeneous process. A bulk process refers to a process where monomer concentration in all feeds to the reactor is 70 volume percent (vol.%) or more. Alternatively, no solvent or diluent is present or added in the reaction medium, (except for the small amounts used as the carrier for the catalyst system or other additives, or amounts typically found with the monomer; e.g., propane in propylene).

[0040] Any suspension, slurry, high pressure tubular or autoclave process, or gas phase polymerization process known in the art can be used under polymerizable conditions. Such processes can be run in a batch, semi-batch, or continuous mode. Heterogeneous polymerization processes (such as gas phase and slurry phaseprocesses) are useful. A heterogeneous process is defined to be a process where the catalyst system is not soluble in the reaction media. Alternatively, in other aspects, the polymerization process is not homogeneous.

[0041] In one or more aspects, the polymerization is performed in the gas phase, such as, in a fluidized bed gas phase process. Generally, in a fluidized bed gas phase process used for producing polymers, a gaseous stream containing one or more monomers is continuously cycled through a fluidized bed in the presence of a metallocene catalyst under reactive conditions. The gaseous stream is withdrawn from the fluidized bed and recycled back into the reactor. Simultaneously, polymer product is withdrawn from the reactor and fresh monomer is added to replace the polymerized monomer.

[0042] In another aspect of the present disclosure, the polymerization is performed in the slurry phase. As used herein a “slurry polymerization process” refers to a polymerization process where a supported metallocene catalyst is employed and monomers are polymerized on the supported catalyst particles. At least 95 wt.% of polymer products derived from the supported metallocene catalyst are in granular from as solid particles (not dissolved in the diluent).

[0043] A slurry polymerization process generally operates between 1 to about 50 atmosphere pressure range (15 psi to 735 psi, 103 kPa to 5068 kPa) or even greater and temperatures as described above. In a slurry polymerization, a suspension of solid, particulate polymer is formed in a liquid polymerization diluent medium to which monomer and comonomers, along with catalysts, are added. The suspension including diluent is intermittently or continuously removed from the reactor where the volatile components are separated from the polymer and recycled, optionally after a distillation, to the reactor. The liquid diluent employed in the polymerization medium is typically an alkane having from 3 to 7 carbon atoms alternatively a branched alkane. The medium employed should be liquid under the conditions of polymerization and relatively inert.

[0044] In an aspect, a polymerization technique utilized is referred to as a particle from polymerization, or a slurry process where the temperature is kept below the temperature at which the polymer goes into solution. The temperature used in the particle from process may be within the range of about 85° C to about 110° C. Alternatively, the polymerization methods for the slurry process are those employing a loop reactor and those utilizing a plurality of stirred reactor in series, parallel, orcombinations thereof. Non-limiting examples of slurry processes include continuous loop or stirred tank processes. In another aspect, the slurry process is carried out continuously in a loop reactor. The metallocene catalyst, as a slurry in isobutane or as a dry free flowing powder, is injected regularly to the reactor loop, which is itself filled with circulating slurry of growing polymer particles in a diluent of isobutane containing monomer and comonomer.

[0045] Hydrogen, optionally, may be added as a molecular weight control. In one aspect 500 ppm or less of hydrogen is added, or 400 ppm or less or 300 ppm or less. In other aspects at least 50 ppm of hydrogen is added, or 100 ppm or more, or 150 ppm or more. Reaction heat is removed through the loop wall since much of the reactor is in the a double-jacketed pipe. The slurry is allowed to exit the reactor at regular intervals or continuously to a heated low pressure flash vessel , rotary dryer and a nitrogen purge column in sequence for removal of the isobutane diluent and all unreacted monomer and comonomers. The resulting hydrocarbon free powder is then compounded for use in various applications.

[0046] Suitable diluents / solvents for polymerization useful herein include noncoordinating, inert liquids. Nonlimiting examples include straight and branched-chain hydrocarbons, such as isobutane, butane, pentane, isopentane, hexanes, isohexane, heptane, octane, dodecane, and mixtures thereof; cyclic and alicyclic hydrocarbons, such as cyclohexane, cycloheptane, methylcyclohexane, methylcycloheptane, and mixtures thereof, such as can be found commercially (Isopar fluids); perhalogenated hydrocarbons, such as perfluorinated C4-C10 alkanes, chlorobenzene, and aromatic and alkylsubstituted aromatic compounds, such as benzene, toluene, mesitylene, and xylene. Nonlimiting example of solvents suitable for use in the polymerization process include liquid olefins which may act as monomers or comonomers including ethylene, propylene, 1 -butene, 1 -hexene, 1 -pentene, 3-methyl-1 -pentene, 4-methyl-1 -pentene, 1 -octene, 1 -decene, and mixtures thereof.

[0047] In at least one aspect, aliphatic hydrocarbon solvents are used as the solvent, such as isobutane, butane, pentane, isopentane, hexanes, isohexane, heptane, octane, dodecane, and mixtures thereof; cyclic and alicyclic hydrocarbons, such as cyclohexane, cycloheptane, methylcyclohexane, methylcycloheptane, and mixtures thereof.

[0048] Suitable polymerizations can be run at any temperature and / or pressure suitable to obtain the desired ethylene polymers. Suitable temperatures and / orpressures may include a temperature in the range of from about 0° C to about 300° C, such as about 20° C to about 200° C, such as about 35° C to about 150° C, such as from about 40° C to about 120° C, such as from about 45° C to about 80° C; and at a pressure in the range of from about 0.35 MPa to about 10 MPa, such as from about 0.45 MPa to about 6 MPa, such as from about 0.5 MPa to about 4 MPa.

[0049] In a suitable polymerization reaction, the run time of the reaction can be up to 300 minutes, such as in the range of from about 5 to 250 minutes or from about 10 to 120 minutes. In a continuous process the run time may be the average residence time of the reactor.

[0050] In at least one aspect, hydrogen is present in the polymerization reactor at a partial pressure of 0.001 to 50 psig (0.007 to 345 kPa), such as from 0.01 to 25 psig (0.07 to 172 kPa), such as 0.1 to 10 psig (0.7 to 70 kPa).

[0051] Other additives may also be used in the polymerization, as desired, such as one or more scavenger, promoters, modifiers, reducing agents, oxidizing agents, hydrogen, aluminum alkyls, silanes, or a combination thereof.

[0052] In one or more aspects, an olefin polymerization process comprises contacting a metallocene catalyst composition of the type disclosed herein with an olefin monomer, optionally hydrogen, and optionally one or more olefin comonomers; and polymerizing the monomer, and the optionally one or more olefin comonomers, in the presence of the metallocene catalyst composition of the type disclosed herein, and optional hydrogen, thereby obtaining an olefin polymer.

[0053] In one or more aspects, the LVPPi comprises a polypropylene that falls between the traditional domains of a PP wax and of a PP with a MFR of greater than about 2100 dg / min.

[0054] In one or more aspects, an LVPPi comprises a reactor-grade isotactic homopolymer polypropylene. Reactor grade polypropylene refers to a polypropylene that has a molecular architecture that matches the polymer immediately after the polymerization reaction.

[0055] In other aspects, the LVPPi comprises a post reactor modified polypropylene. Post-reactor modification could include intentional chemical modification with a 1 ) degradant, 2) crosslinker or 3) reactive branching agent. Polymer modification with a chemical degradant is typically called vis-breaking (viscosity breaking) or controlled rheology (CRing). Another intentional modification would be gamma irradiation, which could induce chain scission or long chain branching. Incidental molecular architecturemodification, such as mild degradation that is inherent under in conventional melt processing conditions, is not considered intentional modification.

[0056] An LVPPi of the type disclosed herein may find utility in applications meltblown fabric manufacturing and as viscosity modifiers in polymer compounds, including compounds containing recycled polypropylene. In one or more aspects, the LVPPi is used in the production of an end use article such as a fiber. Fiber applications are broad and include geotextiles, monofilament, strapping, staple fiber, rope, raffia, carpet backing, carpet face yarn, and spunbond. In other aspects, the LVPPi is used to create a nonwoven article. The nonwovens market is an important segment within the fiber market for polypropylene and the production of articles such as bags, totes, diapers, face masks, medical gowns, filter media, oil absorbent wipes and other articles. The LVPPi because of the melting point and decreased waxy species, provides superior nonwoven fabric performance such as strength and barrier, desirable characteristics for final applications.

[0057] In one or more aspects, a LVPPi of the present disclosure is a component of a formulation that functions as a rheology modifier. In one or more aspects, a LVPPi of the present disclosure is a component of a compounded composition.

[0058] An LVPPi may find utility in the production of low viscosity compounds, such as recycled polymer compositions and hot melt compositions. In such aspects, use of the LVPPi may result in products substantially free of impurities such as peroxide residuals or peroxide byproducts. In one or more aspects, the LVPPi is utilized in automotive compounding. Automotive compounding often has a sophisticated array of physical property and performance requirements.ADDITIONAL DISCLOSURE

[0059] The following are nonlimiting exemplary aspects of the presently disclosed subject matter.

[0060] A first aspect which is a polypropylene having about 30% and about 80% of all molecules within a molecular weight distribution at a molecular weight of greater than 10,000 g / mole; from about 30.0% to about 84% of all molecules within a molecular weight distribution at a critical molecular weight (Mc) of greater than 10,000 g / mole; and a peak molecular weight ranging from about 10,000 g / mol to about 50,000 g / mol.

[0061] A second aspect which is the polypropylene of the first aspect having a polydispersity index ranging from greater than about 2.5 to about 10.

[0062] A third aspect which is the polypropylene of any of the first through second aspects having three or fewer melting peaks.

[0063] A fourth aspect which is the polypropylene of any of the first through third aspects having a first peak at melting temperature of equal to or greater than about 100 °C.

[0064] A fifth aspect which is the polypropylene of any of the first through fourth aspects having the lowest melting temperature of equal to or greater than about 115°C.

[0065] A sixth aspect which is the polypropylene of any of the first through fifth aspects having lowest melting temperature of equal to or greater than about 130 °C.

[0066] A seventh aspect which is the polypropylene of any of the first through sixth aspects having a highest melting temperature no greater than about 183 °C.

[0067] An eighth aspect which is the polypropylene of any of the first through seventh aspects having a highest melting equal to or less than about 170°C.

[0068] A ninth aspect which is the polypropylene of any of the first through eighth aspects having a percent crystallinity of equal to or greater than about 10%.

[0069] A tenth aspect which is the polypropylene of any of the first through ninth aspects having a zero-shear viscosity between about 0.001 Pascal-seconds (Pa-s) to 100 Pascal-seconds at 190°C.

[0070] An eleventh aspect which is the polypropylene of any of the first through tenth aspects having a flexural modulus of from about 25 kpsi to about 400 kpsi.

[0071] A twelfth aspect which is a homopolymer polypropylene, having (i) between about 30% and about 80% of all molecules within a molecular weight distribution at a molecular weight of greater than 10,000 g / mole; (ii) from about 30.0% to about 84.4% of all molecules within a molecular weight distribution at a critical molecular weight (Mc) of greater than 10,000 g / mole; and (iii) an isotactic pentad fraction of equal to or greater than about 94.0 mole% as measured by nuclear magnetic resonance (NMR).

[0072] A thirteenth aspect which is a method of preparing a low viscosity polypropylene, comprising contacting a propylene monomer and optional copolymer with a metallocene catalyst under conditions suitable for the formation of a polypropylene, and recovering the polypropylene.

[0073] A fourteenth aspect which is the method of the thirteenth aspect, wherein the metallocene catalyst is supported.

[0074] A fifteenth aspect which is the method of any of the thirteenth through fourteenth aspects wherein the metallocene catalyst comprises substituted cyclopentadienyl ligands, unsubstituted cyclopentadienyl ligands, or combinations thereof.

[0075] A sixteenth aspect which is a rheology modifier comprising, a polypropylene having (i) from about 30% to about 80% of all molecules within a molecular weight distribution at a molecular weight of greater than 10,000 g / mole; (ii) from about 30.0% to about 84.4% of all molecules within a molecular weight distribution at a critical molecularweight (Mc) of greater than 10,000 g / mole; and (iii) a peak molecular weight ranging from about 10,000 g / mol to about 50,000 g / mol.

[0076] A seventeenth aspect which is the rheology modifier of the sixteenth aspect wherein the polypropylene has a polydispersity index ranging from greater than about 2.5 to about 10.

[0077] An eighteenth aspect which is the rheology modifier of the seventeenth aspect wherein the polypropylene has a primary peak with a melting temperature of equal to or greater than about 148 °C.

[0078] A nineteenth aspect which is the rheology modifier of any of the seventeenth through eighteenth aspects wherein the polypropylene is a metallocene-catalyzed polymer.

[0079] A twentieth aspect which is a meltbown fabric comprising a polypropylene having (i) from about 30% to about 80% of all molecules within a molecular weight distribution at a molecular weight of greater than about 10,000 g / mole; (ii) from about 30.0% to about 84.4% of all molecules within a molecular weight distribution at a critical molecular weight (Mc) of greater than 10,000 g / mole; and (iii) a peak molecular weight ranging from about 10,000 g / mol to about 50,000 g / mol.

[0080] A twenty-first aspect which is a hot melt adhesive comprising, a polypropylene having (i) from about 30% to about 80% of all molecules within a molecular weight distribution at a molecularweight of greater than 10,000 g / mole; (ii) from about 30.0% to about 84.4% of all molecules within a molecular weight distribution at a critical molecular weight (Mc) of greater than 10,000 g / mole; and (iii) a peak molecular weight ranging from about 10,000 g / mol to about 50,000 g / mol.

[0081] A twenty-second aspect which is a polypropylene having a plurality of polymer populations wherein (i) at least one population has molecular chains with a Mw of less than 10,000 g / mol and present in an amount of equal to or greater than about 50% of the total polymer population; (ii) another population having molecular chains with a Mwof less than 1 ,000 g / mol present in an amount of equal to or greater than about 5% of the total polymer population wherein the polypropylene displays a peak molecular weight ranging from about 10,000 g / mol to about 50,000 g / mol.

[0082] While various aspects have been shown and described, modifications thereof can be made by one skilled in the art without departing from the spirit and teachings of the disclosure. The aspects described herein are exemplary only and are not intended to be limiting. Many variations and modifications of the aspects disclosed herein are possible and are within the scope of the disclosure. Where numerical ranges or limitations are expressly stated , such express ranges or limitations should be understood to include iterative ranges or limitations of like magnitude falling within the expressly stated ranges or limitations (e.g. , from about 1 to about 10 includes, 2, 3, 4, etc.; greaterthan 0.10 includes 0.11 , 0.12, 0.13, etc.). Use of the term "optionally" with respect to any element of a claim is intended to mean that the subject element is required, or alternatively , is not required. Both alternatives are intended to be within the scope of the claim. Use of broader terms such as comprises, includes, having, etc. should be understood to provide support for narrower terms such as consisting of, consisting essentially of, comprised substantially of, etc. All test methods are those in effect as of the filing date of this disclosure.

[0083] Accordingly, the scope of protection is not limited by the description set out above but is only limited by the claims which follow, that scope including all equivalents of the subject matter of the claims. Each and every claim is incorporated into the specification as an aspect of the present disclosure. Thus, the claims are a further description and are an addition to the aspects disclosed herein. The discussion of a reference herein is not an admission that it is prior art to the present disclosure, especially any reference that may have a publication date after the priority date of this application. The disclosures of all patents, patent applications, and publications cited herein are hereby incorporated by reference, to the extent that they provide exemplary, procedural or other details supplementary to those set forth herein.

Claims

CLAIMSWhat is claimed is:1 . A polypropylene having: about 30% and about 80% of all molecules within a molecular weight distribution at a molecular weight of greater than 10,000 g / mole: from about 30.0% to about 84% of all molecules within a molecular weight distribution at a critical molecular weight (Mc) of greater than 10,000 g / mole; and a peak molecular weight ranging from about 10,000 g / mol to about 50,000 g / mol.

2. The polypropylene of claim 1 , having a polydispersity index ranging from greater than about 2.5 to about 10.

3. The polypropylene of claim 1 , having three or fewer melting peaks.

4. The polypropylene of claim 1 , having a first peak at melting temperature of equal to or greater than about 100 °C.

5. The polypropylene of claim 1 , having the lowest melting temperature of equal to or greater than about 115°C.

6. The polypropylene of claim 1 , having lowest melting temperature of equal to or greater than about 130 °C.

7. The polypropylene of claim 1 , having a highest melting temperature no greater than about 183 °C.

8. The polypropylene of claim 1 , having a highest melting equal to or less than about 170°C.

9. The polypropylene of claim 1 , having a percent crystallinity of equal to or greater than about 10%.

10. The propylene of claim 1 , having a zero-shear viscosity between about 0.001 Pascal-seconds (Pa-s) to 100 Pascal-seconds at 190°C.11 . The propylene of claim 1 , having a flexural modulus of from about 25 kpsi to about 400 kpsi.

12. A homopolymer polypropylene having:(i) between about 30% and about 80% of all molecules within a molecular weight distribution at a molecular weight of greater than 10,000 g / mole;(ii) from about 30.0% to about 84.4% of all molecules within a molecular weight distribution at a critical molecular weight (Mc) of greater than 10,000 g / mole; and(iii) an isotactic pentad fraction of equal to or greater than about 94.0 mole% as measured by nuclear magnetic resonance (NMR).

13. A method of preparing a low viscosity polypropylene, comprising: contacting a propylene monomer and optional copolymer with a metallocene catalyst under conditions suitable for the formation of a polypropylene, and recovering the polypropylene.

14. The method of claim 13, wherein the metallocene catalyst is supported.

15. The method of claim 13, wherein the metallocene catalyst comprises substituted cyclopentadienyl ligands, unsubstituted cyclopentadienyl ligands, or combinations thereof.

16. A rheology modifier comprising, a polypropylene having:(i) from about 30% to about 80% of all molecules within a molecular weight distribution at a molecular weight of greater than 10,000 g / mole;(ii) from about 30.0% to about 84.4% of all molecules within a molecular weight distribution at a critical molecular weight (Mc) of greater than 10,000 g / mole; and(iii) a peak molecular weight ranging from about 10,000 g / mol to about 50,000 g / mol.

17. The rheology modifier of claim 17, wherein the polypropylene has a polydispersity index ranging from greater than about 2.5 to about 10.

18. The rheology modifier of claim 17, wherein the polypropylene has a primary peak with a melting temperature of equal to or greater than about 148 °C.

19. The rheology modifier of claim 17, wherein the polypropylene is a metallocene- catalyzed polymer.

20. A meltbown fabric comprising a polypropylene having:(i) from about 30% to about 80% of all molecules within a molecular weight distribution at a molecular weight of greater than about 10,000 g / mole;(ii) from about 30.0% to about 84.4% of all molecules within a molecular weight distribution at a critical molecular weight (Mc) of greater than 10,000 g / mole; and(iii) a peak molecular weight ranging from about 10,000 g / mol to about 50,000 g / mol.21 . A hot melt adhesive comprising a polypropylene having:(i) from about 30% to about 80% of all molecules within a molecular weight distribution at a molecular weight of greater than 10,000 g / mole;(ii) from about 30.0% to about 84.4% of all molecules within a molecular weight distribution at a critical molecular weight (Mc) of greater than 10,000 g / mole; and(iii) a peak molecular weight ranging from about 10,000 g / mol to about 50,000 g / mol.

22. A polypropylene having a plurality of polymer populations wherein (i) at least one population has molecular chains with a Mw of less than 10,000 g / mol and present in an amount of equal to or greater than about 50% of the total polymer population; (ii) another population having molecular chains with a Mw of less than 1 ,000 g / mol present in anamount of equal to or greater than about 5% of the total polymer population wherein the polypropylene displays a peak molecular weight ranging from about 10,000 g / mol to about 50,000 g / mol.

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