Unique copolymers comprising propylene, ethylene and/or one or more unsaturated comonomers are characterized as having: at least one, preferably more than one, of the following properties: (i) 13C NMR peaks corresponding to a regio-error at about 14.6 and about 15.7 ppm, the peaks of about equal intensity, (ii) a B-value greater than about 1.4 when the comonomer content of the copolymer is at least about 3 wt%, (iii) a skewness index, S?ix?, greater than about -1.20, (iv) a DSC curve with a Tme that remains essentially the same and a Tmax that decreases as the amount of comonomer in the copolymer is increased, and (v) an X-ray diffraction pattern that reports more gamma-form crystals than a comparable copolymer prepared with a Ziegler-Natta catalyst. These polypropylene polymers are made using a nonmetallocene, metal-centered, heteroaryl ligand catalyst. These polymers can be blended with other polymers, and are useful in the manufacture of films, sheets, foams, fibers and molded articles.

Isotactic propylene copolymers, their preparation and use

The present invention relates to plasticized polyolefin compositions comprising a polyolefin and a non-functionalized hydrocarbon plasticizer.

Plasticized polyolefin compositions

Strain-induced crystallization of natural rubber was discovered in 1925 by the means of x-ray diffraction and has been widely investigated by this technique until today. The studies devoted to the structure of the crystalline phase of natural rubber are first reviewed. This structure is strongly anisotropic and can be related to the exceptionally good strength and fatigue properties of this material. The relationships between strain-induced crystallization of natural rubber and its mechanical response, during static or tension-retraction tests, are also reviewed and discussed; in particular, the hysteresis of the stress-strain curve is mainly explained by strain-induced crystallization. The kinetics of crystallization under both static and cyclic deformation is also discussed, as well as the influence of different factors, depending either on material composition (crosslink density, carbon black fillers) or on external parameters (temperature, strain rate…).

/pdf/strain-induced-crystallization-of-natural-rubber-a-review-of-1ilgu4ftrw.pdf

Strain-induced crystallization of natural rubber: a review of x-ray diffraction investigations

Fibers comprising a propylene homopolymer or a copolymer of propylene and at least one of ethylene and one or more unsaturated comonomers exhibit desirable properties. The homopolymers are characterized as having 13C NMR peaks corresponding to a regio-error at about 14.6 and about 15.7 ppm, the peaks of about equal intensity. The copolymers are characterized as (A) comprising at least about 60 weight percent (wt%) of units derived from propylene, and (B) having at least one of the following properties: (i) 13C NMR peaks corresponding to a regio-error at about 14.6 and about 15.7 ppm, the peaks of about equal intensity, (ii) a 13-value greater than about 1.4 when the comonomer content of the copolymer is at least about 3 wt%, (iii) a skewness index, S?ix?, greater than about -1.20, (iv) a DSC curve with a Tme that remains essentially the same and a Tmax that decreases as the amount of comonomer in the copolymer is increased, and (v) an X-ray diffraction pattern that reports more gamma-form crystals than a comparable copolymer prepared with a Ziegler-Natta (Z-N) catalyst.

Isotactic propylene copolymer fibers, their preparation and use

Fibrous structures that exhibit a novel combination of properties and to methods for making such fibrous structures are provided.

Fibrous structures and methods for making same

Articles and nonwoven fabrics having improved elasticity manufactured from compositions, for example, made from 5 wt % to 100 wt % of a first polymer component of polymers selected from homopolymers of propylene and random copolymers of propylene and from 95 wt % to 0 wt % of a second polymer component of polymers selected from propylene homopolymers and propylene copolymers.

Elastic nonwoven fabrics made from blends of polyolefins and processes for making the same

In-situ structural evolution during uniaxial extension and subsequent retraction of a thermoplastic elastomer (TPE) based on propylene-dominant ethylene−propylene (EP) copolymer was studied. Combined measurements of time-resolved wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) as well as stress−strain curves revealed molecular mechanism responsible for the elastic behavior. During the first cycle of deformation, a fraction of the crystals was destroyed, while the rest was reoriented. At strains larger than 1.0, strain-induced α-crystals in the lamellar form took place, resulting in the creation of a network with well-oriented lamellae having their normals parallel to the stretching direction. With the increase of strain, more crystals were induced, forming an enhanced network with strain-hardening behavior. During retraction and even after complete relaxation to zero stress, the majority of the strain-induced crystalline network remains in tact as being “permanent set”, where l...

Structure Evolution during Cyclic Deformation of an Elastic Propylene-Based Ethylene-Propylene Copolymer

Hetero phase polymer blends are contemplated having a continuous phase of a propylene rich polymer and a dispersed phase of an ethylene polymer, or the dispersed phase can be another propylene rich polymer, or the dispersed phase may be a blend of an ethylene rich polymer and a propylene rich polymer. The crystallinity type of the continuous and dispersed phases are different. The blends exhibit ratio of the 500 % tensile modulus of the blend to the 500 % tensile modulus of the propylene rich polymer component (of the continuous phase), unblended, of ≤ 1.6 at a tension set of ≤ 98 %. The blends may exhibit low flexural modulus properties, generally ≤ 140,000 psi. The propylene rich polymer of the continuous phase also may exhibit a heptane insoluble level < 88 %. Films, fibers, fabrics, and molded articles are among the contemplated uses of the polymer blends.

Elastic blends comprising elastic crystalline polymer and crystallizable polymers for ethylene

The present invention is directed to polymer blend compositions for use as viscosity modifiers comprising at least three ethylene-based copolymer components. The viscosity modifiers described herein comprise a first ethylene-based copolymer having an ethylene content of from about 35 to about 55 wt% and/or a heat of fusion of from about 0 to about 30 J/g, a second ethylene-based copolymer having an ethylene content of from about 55 to about 85 wt% and/or a heat of fusion of from about 30 to about 50 J/g, and a third ethylene-based copolymer having an ethylene content of from about 65 to about 85 wt% and/or a heat of fusion of from about 40 to about 70 J/g. The invention is also directed to lubricant compositions comprising a lubricating basestock and a polymer blend as described herein.

Viscosity modifiers comprising blends of ethylene-based copolymers

This disclosure in certain embodiments relates to thermoplastic sheet compositions and applications incorporating such materials. More specifically this disclosure addresses thermoplastic sheets comprising: a) from 5 to 98.5 wt % of an essentially uncross-linked, random ethylene copolymer having from 20 wt % to 90 wt % repeat units from ethylene and from 10 wt % to 80 wt % of repeat units from one or more other ethylenically unsaturated monomers based upon the weight of the random ethylene copolymer; b) from 0.3 to 83.5 wt % of a polypropylene-based thermoplastic; and c) from 0.3 to 24.5 wt % of a vulcanized rubber dispersed phase. The disclosure also relates to methods of making the sheet compositions. One method includes incorporating a thermoplastic vulcanizate to provide the c) vulcanized rubber and in come cases, to supplement the b) polypropylene thermoplastic. Another method relates to melt blending polymer blends in appropriate proportions in the presence of a curing agent to effect dynamic vulcanization of a cross-linkable rubber component. Improved welding characteristics and weld strength of the sheets and reduced blocking in the extrusion step of producing the sheets is achieved.

Sudhin Datta

Papers

Elastic nonwoven fabrics made from blends of polyolefins and processes for making the same

Structure Evolution during Cyclic Deformation of an Elastic Propylene-Based Ethylene-Propylene Copolymer

Elastic blends comprising elastic crystalline polymer and crystallizable polymers for ethylene

Viscosity modifiers comprising blends of ethylene-based copolymers

Weldable thermoplastic sheet compositions