Influence of diluents on mechanical relaxation behavior of nylon 6 and polyimide

Abstract

Abstract The mechanical relaxation behavior of nylon 6 and of a polyimide have been investigated as a function of water content. In addition, tests have been carried out on nylon 6 samples of both low and high monomer content. Both diluents, water and monomer, act as a plasticizer in nylon 6. They lower the modulus values in the temperature range above 300°K and shift the αa transition to lower temperatures. Water is the more effective plasticizer, the average shift for 1% added diluent being about 20°K as compared to about 2°K for added monomer. Both diluents act like antiplasticizers at low temperatures, raising the modulus and decreasing the intensity of the γ relaxation. As either water or monomer is added, a β relaxation rises in the vicinity of 250°K (103 Hz). It is concluded that the β-relaxation process may arise from reorientational motions of CH2 segments containing nonbonded amide groups as well as from combined motions of such units and associated water molecules. In polyimide water has almost...