D. Heinze, Th. Mang, C. Popescu, O. Weichold
Thermochim. Acta 2016, 637, 143–153
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Effect of side chain length and degree of polymerization on the decomposition and crystallization behaviour of chlorinated poly(vinyl ester) oligomers
ABSTRACT: Four members of a homologous series of chlorinated poly(vinyl ester) oligomers CCl3–(CH2CH(OCO(CH2)mCH3))n–Cl with degrees of polymerization of 10 and 20 were prepared by telomerisationusing carbon tetrachloride. The number of side chain carbon atoms ranges from 2 (poly(vinyl acetate) to 18 (poly(vinyl stearate)). The effect of the n-alkyl side chain length and of the degree of polymerizationon the thermal stability and crystallization behaviour of the synthesized compounds was investigated.All oligomers degrade in two major steps by first losing HCl and side chains with subsequent breakdownof the backbone. The members with short side chains, up to poly(vinyl octanoate), are amorphous andshow internal plasticization, whereas those with high number of side chain carbon atoms are semi-crystalline due to side-chain crystallization. A better packing for poly(vinyl stearate) is also noticeable.The glass transition and melting temperatures as well as the onset temperature of decomposition areinfluenced to a larger extent by the side chain length than by the degree of polymerization. Thermalstability is improved if both the size and number of side chains increase, but only a long side chaincauses a significant increase of the resistance to degradation. This results in a stabilization of PVAc sothat oligomers from poly(vinyl octanoate) on are stable under atmospheric conditions. Thus, the way todesign stable, chlorinated PVEs oligomers is to use a long n-alkyl side chain.