Polypropylene

Geymer, D. O.

doi:10.1016/b978-0-12-219802-1.50008-3

Cited by 5 publications

(1 citation statement)

References 62 publications

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“…The molecular weight changes in PP following low‐dose irradiation have been monitored by osmometry, light scattering, solution viscosity, and melt rheology 12. These studies were consistent, with G ( S ) being slightly greater than G ( X ) but less than 4 G ( X ), so that the weight‐average molecular weight, M W , would become infinite at high doses 9.…”

Section: Introductionmentioning

confidence: 78%

A rheology study of high‐energy radiolysis of a semicrystalline ethylene‐propylene copolymer containing DOP mobilizer

Fuzail

Hill

Park

et al. 2006

J of Applied Polymer Sci

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ABSTRACT:The radiolysis of a poly(ethylene-co-propylene), Elpro grade P 750 J, marketed by Thai Polypropylene Co. Ltd. for the manufacture of medical goods, was investigated at ambient temperature and melt rheology measured. The roles of calcium stearate, blended with the Elpro as a processing aid, and dioctyl phthalate (DOP), added in various amounts as a radical scavenger, were assessed. Following radiolysis, GЈ and the viscosity of the polymer melts at 453 K both decreased with increasing radiation dose, even when the mobilizer was present. The results indicated that although the DOP did scavenge radicals, it did not protect the polymer from net chain scission in a low-dose regimen. The value of (G S Ϫ 4G X ) was approximately 0.6 -0.7.

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Section: Introductionmentioning

confidence: 78%

A rheology study of high‐energy radiolysis of a semicrystalline ethylene‐propylene copolymer containing DOP mobilizer

Fuzail

Hill

Park

et al. 2006

J of Applied Polymer Sci

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Propylene Polymers

Lieberman¹,

Stewart²

2004

Encyclopedia of Polymer Science and Technology

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Polypropylene is one of the most widely used thermoplastics, accounting for one sixth of total consumption of polymeric materials. Many automobiles, textiles, appliances, and other everyday items contain substantial amounts of these polymers. The ability to manufacture a broad variety of polypropylenes having properties tailored for specific applications is the primary factor in its widespread use. Polypropylene is a polymer whose stereoregularity can be controlled, and it exhibits a spectrum of structural variations, because of the ability to control the manner in which the asymmetrum monomer is incorporated into the growing chain, and through the use of comonomers, usually ethylene, which is often used to provide impact‐modified or lower melting polymers. The types of polymers produced, chain‐structural parameters which can be varied and means to characterize them, morophology, thermodynamic properties, processing methods, end use properties, and applications are discussed. Highly stereoselective Ziegler–Natta catalyst are primarily used to produce polypropylene and are the basis for most modern propylene polymerization processes. The historical development of these catalysts, from the early TiCl 3 systems to the modern, high yield MgCl 2 ‐supported systems, including proposed polymerization mechanisms, are discussed. These catalysts enabled the evolution of these polymerization processes from the early slurry process to the current liquid monomer or gas‐phase processes. Metallocene catalysts have increasingly been an area of emphasis and have provided further commerical advances recently. Most major polymerization process in use today are discussed, with the most notable being the Spheripol and Unipol process. Key input into these polypropylene technologies and economics are the technology and infrastructure associated with propylene monomer. The large expansion in polypropylene production in the late 1980s was facilitated by the availability of this newer, less costly polymerization technology. This expansion, well in excess of growth in consumption, caused a dramatic reduction in polypropylene prices in the 1990s, most dramatically in the Far East, where few polypropylene plants existed outside Japan before 1985. Current economic prospects and associated industry trends are discussed.

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The radiation crosslinking and scission of ethylene‐propylene copolymers studied by solid‐state nuclear magnetic resonance

O’Donnell

Whittaker

1985

Brit. Poly. J.

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Methyl groups from chain scission and H‐crosslinks have been identified by solid‐state nuclear magnetic resonance in amorphous ethylene‐propylene copolymers containing 23 and 36 mole % propylene after γ‐irradiation to 10 MGy at 30°C. G (scission) and G (crosslink) values determined from the n.m.r. spectra and by extraction are in agreement, which suggests that the crosslinks are not clustered. This may differ from the situation in polyethylene where there is a substantial crystalline content. G(S). G(X) and the ratio G(S)/G(X) increase with increasing propylene content of the copolymers.

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Polypropylene

Cited by 5 publications

References 62 publications

A rheology study of high‐energy radiolysis of a semicrystalline ethylene‐propylene copolymer containing DOP mobilizer

A rheology study of high‐energy radiolysis of a semicrystalline ethylene‐propylene copolymer containing DOP mobilizer

Propylene Polymers

The radiation crosslinking and scission of ethylene‐propylene copolymers studied by solid‐state nuclear magnetic resonance

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