Solid-state polyamidation of nylon salts

Solid-state polyamidation (SSP) processes may proceed through intermediates of lower melting point, resulting in a distinct solid-melt transition (SMT). In this study an attempt is made to correlate the phenomenon with structural characteristics of the starting material. Nylon salts formed from aliphatic diamines and aliphatic diacids were considered forst and, surprisingly, the same transitional behaviour was eventually detected independent of salt nature. However, when research was oriented to better organized salt structures, to effect increased resistance to hydration, the picture changed: ethylenediammonium fumarate provides no evidence for transition even at a reaction temperature closely approaching its decomposition point.