Configurational characteristics of ethylene-vinyl chloride copolymers

Abstract

Rotational isomeric state theory has been used to calculate mean-square unperturbed dimensions r2> and dipole moments 2> of ethylene-vinyl chloride copolymers as a function of chemical composition, chemical sequence distribution, and stereochemical composition of the vinyl chloride sequences. As was previously found for several other copolymeric chains, 2> is much more sensitive to chemical composition and chemical sequence distribution than is r2>0. The present calculations also indicate that both r2>0 and 2> are most strongly dependent on chemical sequence distribution for ethylene-vinyl chloride chains having vinyl chloride sequences which are significantly syndiotactic in structure. In the case of ethylene-vinyl chloride copolymers in which the chemical sequences are relatively short and the vinyl chloride sequences are significantly isotactic, both r2>0 and 2> depend on chemical composition in an unexpectedly complex manner; under the cited conditions both of these statistical properties display a maximum and minimum in their variation with chemical composition.