Rubber elasticity of preswollen polymer networks: Lightly crosslinked vinyl‐divinyl systems

The rubber elasticity of lightly crosslinked, preswollen polymers is studied by both stress‐relaxation and torsion measurements. The equation of state of rubber elasticity is applied to evaluate their front factors. It is found that both elastic moduli and front factors decrease linearly as the diluent content increases. This relationship is independent of the type of crosslink and the diluent used. Properties of deswollen polymer networks are also investigated. No significant change in front factor is apparent before and after deswelling. All these observations are attributed to the network topology. One factor is that effective chemical crosslinks may be decreased by the formation of intramolecular loops. Also, trapped entanglements become less significant at higher diluent concentrations.