Differential thermal analysis of high polymers. III. Polyamides

Abstract

Abstract Differential thermal analysis has been used to study melting and glass transitions in various homo‐ and copolyamides, as well as crystallite disorientation in nylon monofilaments. Transition temperatures obtained from the thermograms of the commoner polyamides agree well with literature values, but the less common polyamides gave slightly higher melting points. Heats of fusion of polyamides 66 and 610 were obtained from the thermograms by calibration with a calorimetric standard. These values together with the independently determined degree of crystallinity have been used to calculate the true heats of fusion. The thermograms of two series of copolyamides, the adipamide–sebacamides and adipamide–terephthalamides, showed changes in peak shapes, positions, and areas from those of the parent homopolymers. Decrease in crystallinity led to pronounced glass transitions. Two melting peaks observed for certain copolymers are interpreted as evidence for the production of block copolymers, which are favored by the reaction conditions existing in interfacial polycondensations.