Effect of bimodality on tear properties of silicone networks

Abstract

The effect of blending a short and a long chain prepolymer, i.e. the effect of biomodality, and that of concentration of the crosslinker on mechanical properties has been inves-tigated. The content of short chain prepolymer was varied from 0 to 80 wt.-%. Different concentrations of crosslinker, 3.9, 9.1 and 12.3 wt.-%, were used for the bimodal mixtures. It was found that the enhancement of tear properties was dependent upon both the bimodality and the amount of crosslinker used for curing. It has been shown that the enhancement cannot be explained in terms of the existing theoretical equations for tear properties.