SOLID-STATE POLYAMIDATION OF ALIPHATIC DIAMINE ALIPHATIC DIACID SALTS - A GENERALIZED MECHANISM FOR THE EFFECT OF POLYCONDENSATION WATER ON REACTION BEHAVIOR

Polycondensation reactions on nylon salts can be carried out in the melt or, alternatively, in the solid state. Nevertheless, in the latter case, a distinct transition to the melt state may take place, depending on the nature of the nylon salt and reaction temperature. For the particular case of the dodecamethylenediammonium adipate this phenomenon has been attributed to water accumulation within the reacting structure. In this paper, based on previously reported preliminary results, the generalization of this mechanism is attempted for other typical cases of nylon salts, namely tetra- and hexamethylenediammonium adipate, and hexa- and dodecamethylenediammonium sebacate. All these salts when polymerized in the solid state may pass through a melt or quasi-melt stage. The polymerization runs were monitored both by end groups and water determinations. The experimental data obtained support the proposed mechanism according to which the polycondensation water tends to be sorbed at the polar hydrophilic groups with next effect the disturbance of the reacting regular structure. Then the mobility of the system increases and more water can be diffused out, but the reaction temperature plays a predominant role in the overall reaction behaviour. © 1990.