KINETICS OF SIMULTANEOUS INTERPENETRATING POLYMER NETWORKS OF POLY(DIMETHYLSILOXANE-URETHANE) POLY(METHYL METHACRYLATE) FORMATION AND STUDIES OF THEIR PHASE MORPHOLOGY

Kinetics studies of simultaneous interpenetrating polymer networks (SI PNs) of oly-(dimethylsiloxane-urethane)(PDMSU)/poly(methyl methacrylat e)(PMMA) have been carried out by means of differential scanning calor imetry (DSC) with computer-aided DSC data analysis programs. The kinet ic parameters such as conversion versus time and temperature, heat of reaction DELTAH, activation energy DELTAE, and reaction order n have b een investigated by DSC isothermal and scanning modes. The experimenta l evidence clearly showed that the phase morphology of the SIPN of PDM SU/PMMA was changed by changing rates of their cross-linking reactions . A miscible IPN with 80 wt % PDMSU made with well-matched rates of cr oss-linking reactions in the network formation exhibited one glass tra nsition temperature (T(g)) and no SEM observable phase domains. Howeve r, an immiscible IPN with the same composition of PDMSU could be prepa red with a much slower cross-linking reaction producing a phase-separa ted IPN with two T(g)s from DSC measurements and a heterogeneous phase morphology observed by SEM.