Some Properties of Poly-(hexamethylene adipamide) in View of Terminal Group Balance

抄録

An attempt was made to elucidate the effect of the terminal group on physical, rheological and thermal properties of poly-(hexamethylene adipamide) (nylon 66). For this purpose, the experiments on melt-flow, water adsorption and thermal behavior for nylon 66 chips having different molar fractions of amino terminal group ƒ_N were carried out as well as structural analysis on the as-extruded yarns. It was found that an increase in ƒ_N resulted in 1) the lowering of water absorption rate, 2) the increasing in activation energy for the melt flow for the nylon 66 chips, and 3) the increase in tan δ_max and the decrease in T_max for α relaxation of the as-extruded yarns at 300°C . Analysis based on the rubber elastic theory for the melt revealed that higher activation energy is required for nylon 66 with larger ƒ_N but failed to detect the evidence for the presence of chemical or pseudo-cross-linking for nylon 66 with higher ƒ_N. These results support the idea that nylon 66 with high ƒ_N has inherently stronger molecular interaction in the amorphous region to hinder the structural formation induced by heat and humidity.