X-ray Analysis of the Structure of Wholly Aromatic Copolyamides and Copolyester Carbonates

Abstract

AbstractThis paper summarizes our work on the structures of two wholly aromatic copolymers: the copolyamide prepared from terephthalic acid, phenylene diamine, and 3,4'-diaminodiphenyl ether (mole ratio 50/25/25) and the copolyester carbonate prepared from p-hydroxy benzoic acid and hydroquinone, with the introduction of carbonate units (mole ratio 60/20/20). X-ray fiber diagrams of both copolymers exhibit a number of aperiodic meridional maxima that are similar to those reported for a series of wholly aromatic copolyesters. The latter systems have been shown to consist of arrays of parallel chains of completely random comonomer sequence: the aperiodic maxima arise due to structural correlations along the extended random sequences. The structures studied in the present paper are more complex due to the presence of kinked units, i.e. the 1,3 phenylenes and ether linkages of the copolyamide, and the carbonate groups of the copolyester carbonate. The results obtained show that the x-ray data can be explained by completely random monomer sequences. However, the chains are significantly distorted in order to produce more extended conformations than might be expected for isolated chains. These distortions minimize the effects of the kinked units and lead to better chain packing.