ISOTHERMAL REACTION-KINETICS AND PHASE-BEHAVIOR ANALYSIS IN THE FORMATION OF PCU PMMA INTERPENETRATING POLYMER NETWORKS

Isothermal reaction kinetic and phase behavior studies have been carri ed out on simultaneous interpenetrating polymer networks (SIPNs) of po ly(carbonate-urethane) (PCU)/poly(methyl methacrylate) (PMMA) and rela ted materials via differential scanning calorimetry (DSC) with a compu ter-aided DSC data analysis program. The kinetic parameters such as co nversion versus time and temperature, activation energy, and reaction order have been investigated by a DSC isothermal method. The data from the DSC isothermal experiment are in good agreement with gravimetric kinetic data. The phase behavior of SIPNs of PCU/PMMA and related mate rials have been analyzed by means of DSC, SEM, and TEM. The results sh owed that the original one phase morphology of SIPNs of PCU/PMMA can b e changed to a two phase morphopogy by changing the kinetics of networ k formation. Two phase SIPN of PCU/PMMA have been obtained by employin g nonsimultaneous cross-linking reactions for the two different networ ks while a one phase SIPN of PCU/PMMA can be made if the gelation time s for both networks matched. The T(g)'s of the products increased with the increasing degree of conversion, possibly due to higher degrees o f cross-linking with higher conversion.