OPTICALLY CLEAR SIMULTANEOUS INTERPENETRATING POLYMER NETWORKS BASED ON POLY(ETHYLENE GLYCOL)DIACRYLATE AND EPOXY .2. KINETIC-STUDY

Simultaneous interpenetrating polymer networks (SINs) based on diglycidyl ether of bisphenol A (DGEBA) and poly(ethylene glycol) diacrylate (PEGDA) in weight ratios of 100/0, 50/50, and 0/ 100 were blended and cured simultaneously by using benzoyl peroxide (BPO) and m-xylenediamine (MXDA) as curing agents. A kinetic study during SIN formation was carried out at 45, 55, 63, and 70-degrees-C. Concentration changes for both the epoxide and C = C bond were monitored with FTIR. A rate expression for DGEBA cure kinetics was established with a model reaction of phenyl glycidyl ether (PGE) and benzylamine. Experimental results revealed that lower rate constants and higher activation energy for the SIN were found, compared with those for the constituent DGEBA and PEGDA network formation. A model of network interlock was proposed to account for this phenomenon. During simultaneous cure of DGEBA and PEGDA, the interlock (mutual entanglement) between DGEBA and PEGDA networks provided a sterically hindered environment, which subsequently increased the activation energy and reduced cure rates for both DGEBA and PEGDA. (C) 1993 John Wiley & Sons, Inc.