AbstractThe effect of blending a short and a long chain silicone prepolymer, that is, the effect of bimodality on tear properties of filled polymer networks has been investigated. Two concentrations, namely, 17.2 and 30.2% w/w of the filler (HDK) were used. The contents of short chain prepolymers have been varied from 0 to 69% w/w and 0 to 58% w/w for 17.2 and 30.2% filled polymer, respectively. The concentration of crosslinker and catalyst added were kept constant, namely, 13.79 and 0.07%, respectively, for each composition. It has been shown that up to a threshold concentration of filler and short chain prepolymers, the application of bimodality has beneficial effects of increasing tear energy up to 3.5 times that of the tear energy of the concerned filled monomodal polymer network. Above this threshold limit, further increase in concentration of filler or short chain prepolymers, contrary to expectation, adversely affected the tear properties of the filled polymer networks. In light of the results obtained, the mechanism of enhancement in the tear properties of the polymer network due to bimodality in the filled polymer system has been discussed. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1719–1722, 2004