Semi‐ and fully interpenetrating polymer networks based on polyurethane–polyacrylate systems. I. The polyurethane networks

The polyurethane networks based on commerical prepolymer, Adiprene L‐100, and trimethylol propane (system 1) and on toluene diisocyanate, polypropylene gylcol, and trimethylol propane (system 2) were prepared and characterized in a number of ways. The materials constitute the first formed networks in a series of interpenetrating polymer networks and semi‐interpenetrating polymer networks to be reported in subsequent papers in this series. System 1 networks were characterized by swelling tests which showed the M c values to be sensitive to the amount of polyurethane present in the polymerization solvent. Stress–strain, stress–relaxation, and dynamic mechanical analyses wer also conducted. For system 2, M c was measured, by both the swelling and the Mooney–Rivlin techniques, for materials in which the diol‐to‐triol ratios had been altered. the latter showed C 1 increasing as M c decreased while C 2 was small and changed onlyy slightly indicating approximately ideal behavior. These M c values were about 13 % larger than predicted by swelling.