SYNTHESIS AND CHARACTERIZATION OF GLYCINE COPOLYMERS OF NYLON-6 AND NYLON-12

Copolymers of glycine and 6-aminohexanoic or 12-aminododecanoic acid within a range of molar compositions from 80/20 to 5/95 were prepared by solution polycondensation of the adequate proportion of the respective pentachlorophenyl ester hydrobromides. Despite their random composition, the copolymers obtained were found to be highly crystalline. Intrinsic viscosities of 2/6 and 2/12 copolyamides were similar and rather low (M(n), ca. 3000-5000). Thermal post-polycondensation allowed to increase the molecular weight of 2/12 copolyamides, so that fibers could be prepared. The composition and sequence distributions were evaluated by means of H-1- and C-13-NMR spectroscopies. Copolyamides were also characterized in terms of thermal properties. Melting and glass transition temperatures are reported. Crystallinity was evaluated from heats of fusion. Crystalline structure was examined by infrared spectroscopy and wide-angle x-ray diffraction. The presence of structures related to the polyglycine I and to alpha/gamma-nylons was confirmed depending on the molar composition. Highly oriented fibers with good tensile properties were obtained from the nylon 2/12 (10 : 90) copolymer. (C) 1995 John Wiley & Sons, Inc.