Influence of static strain on viscoelastic phenomena associated with the glass-rubber transition of elastomers prepared from poly(neopentylglycol adipate)

Abstract

Dynamic loss tangent measurements performed on poly(neopentylglycol adipate) networks in the temperature range − 140 to − 10°C show the existence of a well defined α absorption, associated with the glass-rubber transition, and a β absorption in the glassy region which is presumably caused by molecular motions in which the bulky neopentyl residue intervenes. The results obtained from dynamic deformations of small amplitude, superimposed on strained networks, indicate that the intensity of the loss tangent associated with the α transition tends to increase with the static deformation. The free volume interpretation of the experimental results gives a good account of the α relaxation for both unstrained and strained networks. Moreover, the analysis of the glass-rubber transition in terms of Eyring theory suggests that in the present system the compensation law holds.