Silicone networks with junctions of high functionality and the theory of rubber elasticity

Abstract Results of Krik, Bidstrup, Merrill, and Meyers on polydimethylsiloxane networks of high functionality ϕ yield values of the reduced force [f*] in the high‐extension limit that are directly proportional to ( v s / V ) (1 − 2/ϕ) where v s / V is the number of effective chains in volume V . The contention that trapped entanglements contribute significantly to the modulus is refuted by adherence of the results to this proportionality down to the lowest degrees of interlinking. Features of the relationship of stress to strain that appear to be in conflict with current theory are attributable to crowding of chains about the junctions of high functionality and of large linear dimension in the networks investigated by these authors.