Crystalline order in copolymers of ethylene and propylene

Starkweather, Howard W.; Van-Catledge, F. A.; MacDonald, Robert N.

doi:10.1021/ma00234a027

Cited by 33 publications

(19 citation statements)

References 4 publications

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“…On irradiation, segments transition from a disordered modification to a more ordered goes through recrystallization. 29 Molecular mechanics calculations 30 on model compounds also indicated that isolated ethylene units and EPR may be embedded the PP matrix. It appears that the amorphous material on irradiation makes domains of the dispersed PE phase smaller and more uniform and therefore Xe increases.…”

Section: Changes In X-ray Diffractionmentioning

confidence: 99%

Effect of UV Irradiation on The Structure of Heterophasic Ethylene-Propylene Copolymers

Ramanathan

Singh

Sivaram

et al. 1994

Polym J

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ABSTRACT:Changes in [17] and crystallinity of commercial samples of isotactic polypropylene (i-PP), heterophasic ethylene-propylene copolymers [E-P copolymer] containing < 16mol% of ethylene and their fractions (having ethylene content 40.9 and 55. 7 mo!%) upon polychromatic irradiation in air at 55°C were studied by comparing unirradiated samples. Crystallinity was evaluated by DSC and X-ray diffraction. Viscosity results showed a decrease of molecular weight upon irradiation. DSC and X-ray studies revealed that the transition of ex-modification to /I-phase of polypropylene and also that crystallinity of the copolymer decreased initially upon irradiation. However, upon longer irradiation, the crystallinity increased again.

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Section: Changes In X-ray Diffractionmentioning

confidence: 99%

Effect of UV Irradiation on The Structure of Heterophasic Ethylene-Propylene Copolymers

Ramanathan

Singh

Sivaram

et al. 1994

Polym J

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“…However, deficiencies, such as natural brittleness, prohibit its broader application 23, 24. Numerous investigations on the toughening blends of PP with various elastomers, such as ethylene–propylene–diene block copolymer (EPDM), poly(ethylene‐ co ‐1‐octene) (POE), styrene–butadiene–styrene block copolymer (SBS) and so on, have been reported in the past decades 25–27. Although a satisfied toughening effect comes from these systems, the deterioration in tensile strengths and stiffness also fazes the developers.…”

Section: Introductionmentioning

confidence: 99%

Synchronous toughening and reinforcing of polypropylene with ultrahigh‐molecular‐weight polyethylene via melt blending: Mechanical properties, morphology, and rheology

Wang

Jin

2006

J of Applied Polymer Sci

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ABSTRACT:Blending systems based on polypropylene (PP) and ultrahigh-molecular-weight polyethylene (UHM-WPE) were prepared via a melt extrusion by the four-screw and the twin-screw extruders, respectively. The mechanical evaluation demonstrated that the synchronous toughening and reinforcing effects could be achieved from the combination of the PP and the UHMWPE, in which the toughness and the tensile properties could be improved with increasing the UHMWPE content, and achieved optimal values at a weight ratio of PP/UHMWPE (85/15). EPDM can be used as a compatibilizer to improve the compatibility and the interfacial adhesion between the PP and the UHMWPE. This resulted in more effective toughening and reinforcing effects. In contrast, for the PP/UHMWPE blends prepared by the normal twin-screw extruder, the poor dispersion capacity for the UHMWPE resulted in a deterioration of all mechanical parameters. Morphological observation revealed that the UHMWPE domain was well distributed as tiny particles in the PP matrix, which was confirmed by the differential scanning calorimetry analysis. The toughening effect was attributed to the energy dissipation caused by these rigid tiny particles that detached from the matrix to initiate the local matrix shear yield and formed the void. Rheological investigation demonstrated that there was an interesting composition dependence of viscosity, for which the melt viscosities of the PP/UHMWPE blends decreased when 5 wt % UHMWPE was added, and then began to increase as the UHMWPE content continued to increase. However, this dependence on composition became weaker because of the compatibilization of the EPDM.

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“…The participation of ethylene units in the propylene crystalline lattice is a subject of interest. On the basis of molecular mechanics calculations for model compounds 25 or on the invariance of the crystallinity and the crystal thickness with increasing ethylene content, 26 certain authors have concluded that the ethylene units are partially included in the crystal. In other reports, the decrease of the melting temperature with increasing comonomer concentration 27 has led to the conclusion that the ethylene units are rejected from the crystal.…”

Section: Tm-afm Morphological Analysismentioning

confidence: 99%

Morphological analysis of highly filled propylene/ethylene copolymers

Ionescu-Vasii

Wood‐Adams

Duchesne

et al. 2007

J of Applied Polymer Sci

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A series of particulate composites based on a new family of propylene/ethylene (P/E) copolymers produced by Dow Chemical Co. were studied with microscopy and differential scanning calorimetry (DSC). To understand the good processability exhibited by the composites, we studied the composite microstructure and the bulk rheological properties. Here we report the results of a study of the microstructure and thermal behavior. Electron micrographs of the composites showed a uniform dispersion of the particles in the copolymer matrices at all experimental concentrations with very little particle agglomeration. The images suggested low adhesion between the matrices and the particles. The copolymers were semicrystalline, and their morphologies changed with the ethylene content. An increase in the ethylene content led to a decrease in the crystallinity and changes in the shape and size of the crystallites. Tapping-mode atomic force microcopy images of a 9 wt % ethylene copolymer contained spherulites, lamellae, and a crosshatched structure characteristic of a-isotactic polypropylene. The crosshatched structure was not present at higher ethylene contents. A DSC study of the pure copolymers and their composites revealed that only very small modifications to the thermal behavior of the P/E copolymers were induced by calcium carbonate particles.

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Crystalline order in copolymers of ethylene and propylene

Cited by 33 publications

References 4 publications

Effect of UV Irradiation on The Structure of Heterophasic Ethylene-Propylene Copolymers

Effect of UV Irradiation on The Structure of Heterophasic Ethylene-Propylene Copolymers

Synchronous toughening and reinforcing of polypropylene with ultrahigh‐molecular‐weight polyethylene via melt blending: Mechanical properties, morphology, and rheology

Morphological analysis of highly filled propylene/ethylene copolymers

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