The conformational and intermolecular contributions to the residual enthalpy AH o and entropy S~ at 0 K for amorphous nylon-6 and nylon-6,6 were investigated on the basis of the derivation of a new relationship between Cp and C,,. It was found that AH o contains only the intermolecular enthalpy for CONH residues in amorphous nylon-6 and nylon-6,6. The conformational contribution to S~ consists, on the basis of the conformations, of 49 kinds of rotational isomeric states for nylon-6 and 2401 (49 x 49) kinds for nylon-6,6, independently of temperature. The intermolecular contributions to S~ are only due to CONH residues in these polymers. Next, through the investigation of the conformational contributions to the glass transition, the possibility of ordered regions in nylon-6 and nylon-6,6 glasses was explored. The existence of localized and ordered parts with enthalpies of 40.1 kJ tool-~ for nylon-6 and 80.7 kJ mol-~ for nylon-6,6 is predicted. The enthalpies of the localized ordered parts are somewhat larger than the glass transition enthalpies of 37.6 kJ mol-1 for nylon-6 and 75.2 kJ mol-i for nylon-6,6, respectively.
(Keywords: polyamide; ordered regions; heat capacity) the enthalpy and the Gibbs free energy as functions of P and T, fl(P, T) is the partition function as a function