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Many kinds of polyethylene are known, with most having the chemical formula (C 2 H 4) n. PE is usually a mixture of similar polymers of ethylene, with various values of n. It can be low-density or high-density and many variations thereof. Its properties can be modified further by crosslinking or copolymerization.
Polyethylene Polypropylene Polyisobutylene Polyurethane Polyester Polycarbonate Vinyl polymers PVC PVA ... block copolymer: A copolymer that is a block polymer.
The EVA copolymer which is based on a low proportion of VA (approximately up to 4%) may be referred to as vinyl acetate modified polyethylene. It is a copolymer and is processed as a thermoplastic material – just like low-density polyethylene. It has some of the properties of a low-density polyethylene but increased gloss (useful for film ...
Linear low-density polyethylene (LLDPE) granules. Linear low-density polyethylene (LLDPE) is a substantially linear polymer (polyethylene), with significant numbers of short branches, commonly made by copolymerization of ethylene with longer-chain olefins.
The development of coordination polymerization that enables copolymerization with polar monomers is more recent. [4] Examples of monomers that can be incorporated are methyl vinyl ketones, [5] methyl acrylate, [6] and acrylonitrile. [7] Illustrative metallocene-based coordination catalysts
Butyl rubber (IIR) by low temperature cationic copolymerization of isobutylene with isoprene in ethylene or methylchloride solution. Aromatic polyamides (e.g. Kevlar and Nomex) are made by polycondensation in N-methyl-pyrrolidone and calcium chloride solution.
There is a corresponding intense market for new processes as indicated by the fact that, in the US alone, 50,000 patents were issued between 1991-2007 on polyethylene and polypropylene. [ 1 ] Many methods exist to polymerize alkenes, including the traditional routes using Philips catalyst and traditional heterogeneous Ziegler-Natta catalysts ...
For the copolymerization of a given pair of monomers, the two experimental reactivity ratios r 1 and r 2 permit the evaluation of (Q 1 /Q 2) and (e 1 – e 2). Values for each monomer can then be assigned relative to a reference monomer, usually chosen as styrene with the arbitrary values Q = 1.0 and e = –0.8. [28]