ON THE STRUCTURE AND SOME PROPERTIES OF NYLON 66 COPOLYMERS

Abstract

Nylon 66 copolymers were prepared by substitutions up to 50 mol%, of diacid comonomers: terephthalic acid (T), isophthalic acid (I) and 1, 2-diphenoxyethane-p, p′-dicarboxylic acid (B), and diamine comonomers: p-xylylenediamine (PXD), m-xylylenediamine (MXD), p-phenylenediamine (P), m-phenylenediamine (M), 4, 4′-diaminodiphenylmethane (C), 4, 4′-diaminodiphenylether (0), 4, 4′-diaminodiphenylsulfone (S) and piperazine (Pip). The amorphous samples of these copolymers were subjected to the following measurements: glass transition temperature (Tg) and cold crystallization temperature (Tcc) by DTA method, and density.Tg's of N66-6I and N66-MXD6 conform to Gibbs-Dimarzio's equation and Wood's equation, whereas Tg's and densities of p-phenylene type copolymers (N66-6T, N66-PXD6 and N66-P6) are higher than those of corresponding m-phenylene type copolymers (N66-6I, N66-MXD6 and N66-M6). Tg's and densities of pdiphenylenediamine type copolymers increase in the following order: N66-C6<N66-06<N66-S6. Tg's of N66-6B are lower than those of above p-diphenylenediamine type copolymers. Tg's of N66-Pip6 are lowest among the copolymers studied. (Tg-Tcc) of N66-6T and N66-PXD6 are lower than those of N66-6I, N66-MXD6, N610-6T and N610-6I, which suggests that N66-PXD6 is isomorphous. The isomorphism of N66-PXD6 is supported by the fact that the results of dynamic viscoelastic measurement are similar to those of isomorphous N66-6T.