Transport of water through polyamide-nitrile rubber blends and its influence on mechanical properties

Polyamide-nitrile rubber blends of high polyamide content (100/0, 70/30, 50 /50) were prepared by melt mixing in a Haake Rheocord. The diffusion of wat er through the blends was investigated at various temperatures; 28, 45, 65 and 75 degreesC. The temperature dependence of the diffusion characteristic s indicates that the transport mechanism varied with blend composition, mor phology and temperature. The weight gain curves for pure polyamide and blen ds rich in polyamide showed a maximum followed by a decrease (overshoot eff ect). The enthalpy and entropy of sorption have been computed from the sorp tion data. Transport was found to follow the Fickian type mechanism. The ef fects of water uptake on the mechanical behaviour of the blends have also b een analysed. The mechanical properties were found to decrease considerably as a result of water absorption.