Configurational characteristics of ethylene- vinyl chloride copolymers
نویسنده
چکیده
Rotational isomeric state theory has been used to calculate mean-square unperturbed dimensions (r2>0 and dipole moments (/~> 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, (/z2> 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 (/z~) 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 (rZ)o and (/z z) 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.
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