Abstract: A hygrothermal aging experiment was conducted for polyhexamethylene terephthalamide (PA6T) at 20, 90 and 150 ℃, and effect of aging time on physical and mechanical properties of PA6T specimens was investigated. The results indicated that water absorption of PA6T increased with an increase of aging time, and its diffusion coefficient and equilibrium moisture absorption were also improved as the aging temperature increased. There was no change in intrinsic viscosity observed from of PA6T specimens at 20 and 90 ℃. However, the intrinsic viscosity decreased evidently at 150 ℃ because of the hydrolysis of PA6T. The impact strength of PA6T was enhanced due to the increase of activity of its molecular chains. Furthermore, hydrogen bonding between water and amide groups led to an increase in tensile modulus.

Key words: poly(hexamethylene terephthalamide), hydrothermal aging, mechanical property