Aliphatic polyolefins poly-

Polymers have been grouped into the following 10 categories aliphatic polyolefins, polystyrenes, polyvinyl halides, polyvinyl esters, cellulose esters, polyvinyl ethers, poly-ethers, aromatic polymers, copolymers and miscellaneous polymers. The molar cohesive energies (Eg) were calculated from their respective group increments according to the following equation ... 

These are the polymers which are based on unseparated aliphatic hydrocarbons containing are double bond in molecule. The important polyolefins are polyethylene, polypropylene, poly (isobutene) and poly (4-methyl 1-pentene). 

The principal polyolefins are low-density polyethylene (ldpe), high-density polyethylene (hope), linear low-density polyethylene (lldpe), polypropylene (PP), polyisobutylene (PIB), poly-1-butene (PB), copolymers of ethylene and propylene (EP), and proprietary copolymers of ethylene and alpha olefins. Since all these polymers are aliphatic hydrocarbons, the amorphous polymers are soluble in aliphatic hydrocarbon solvents with similar solubility parameters. Like other alkanes, they are resistant to attack by most ionic and most polar chemicals their usual reactions are limited to combustion, chemical oxidation, chlorination, nitration, and free-radical reactions. 

To understand these reactions, the so-called Bolland and Gee reaction scheme17-18 and its subsequent developments has been applied to explain the chain reaction characteristics of both thermal and photooxidation of polyolefins. The scheme (Scheme 2.1) has been found to be a useful model for many other polymers comprising significant aliphatic character, such as aliphatic polyamides and polyesters and certain polyvinyls including poly(vinyl chloride) (PVC). 

In the context of this chapter, the use of thermoplastic starch in blends with thermoplastic resins is of the main interest. As shown in Table 16.11, several blends have been developed, e.g., with vinyl alcohol copolymers (EVAl), polyolefins, aliphatic polyesters such as poly-e-caprolactone (PCL) and its copolymers, or polymers of glycols (e.g., 1,4-butanediol) with succinic, sebacic, adipic, azelaic, decanoic or brassihc acids, PCL + PVC. Compatibilization is possible by amylose/EVAl V-type complexes, starch grafted polyesters, chain extenders like diisocyanates, epoxies, etc. [Bastioli et al., 1992, 1993]. 

PCL -OCH CH CH CH CH CO-ln) is a partially-crystalline polyester that is biodegraded by microbial lipases and esterases. The plastic is made from petrochemical feedstocks. It has too low a melting point (60°C) to be useful in any packaging applications. Higher aliphatic polyesters such as poly(butylene succinate) (PBS) (-0(CH2) OC(CH2)2CO-)n and poly(ethylene succinate) (PES) (-OCCH l OOCCCH l CO-) are also biodegradable at a rate that depends on environmental factors (Kasuya et al., 1997). They have higher melting points of 112-114°C and 103-106°C, respectively, and the properties compare well to those of polyolefins. As succinic acid can be derived from plant sources, the polysuccinates can be potentially a bio-based polymer. 

Synthetic polymers are an integral part of everyday life. Synthetic polymers in the form of polyolefins such as polypropylene and polyethylene and other synthetic polymers such as poly(acrylate)s and poly(styrene)s (PSs) are predominantly used in packaging materials. Condensation polymers are produced in smaller amounts than addition polymers. Nevertheless, some condensation polymers such as polyesters with specific reference to poly(ethylene terephthalate) (PET) and aliphatic polyethers, aliphatic polyamides (i.e., nylons), and polysiloxanes are quite important. 

Polyolefins Polystyrenes Polyacrylates Polymethacrylates Polyacrylonitriles Polyacrylamides Poly(vinyl halides) Poly(vinylidene halides) Poly(vinyl ethers) Poly(vinyl ketones) Poly(vinyl esters) Poly(vinyl pyridines) Polydienes Polyethers Polyesters, aliphatic Polyesters, aromatic Polyamides Polysiloxanes Polyphosphazenes Polysulfones... 

For the purposes of this chapter, polyolefins are defined as polymers based on unsaturated aliphatic hydrocarbons containing one double bond per molecule. Polymers derived from unsaturated aromatic hydrocarbons and dienes are considered in later chapters. At the present time the principal commercial polyolefins are polyethylene (polythene), polypropylene, polyisobutene, polybut-l-ene and poly-4-methylpent-l-ene together with related copolymers. These polymers are considered individually in subsequent sections after a brief account of relevant raw materials. 

Poly ketone Resins n A new and unique family of aliphatic polymers composed of carbon monoxide, ethylene and minor amounts of other alpha olefins. This family of semicrystalline resins exhibits many of the properties of engineering resins while processing similarly to polyolefins. 

The commercial polyester elastomers are mostly based on poly(tetrameth-ylene oxide) (PTMO) as flexible segment and poly(butylene terephthalate) (PBT) as rigid segment. Yet, many chemical modifications of some particular segments and also segments of totally different chemical structure have been examined and applied. Thus, in addition to PTMO [1,2,11-16], poly(ethylene oxide) (PEO) [17-22], poly(aliphatic oxide) (C2-C4) copolymers [23-30], poly (butylene succinate), and other aliphatic polyesters [31-35], polycaprolac-tone (PCL), polypivalolactone (PVL) [36,37], aliphatic polycarbonates (PC) [38-41], dimerized fatty acid (DFA)-based polyesters [42-50], polyamide 66 and derivatives [47-57], polyolefins [58-60], rubbers [61-63], and polydimethyl-siloxane [64,65] are used as flexible segments of polyester elastomers. 

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