KINETIC-STUDY ON SIMULTANEOUS INTERPENETRATING POLYMER NETWORK FORMATION OF EPOXY-RESIN AND UNSATURATED POLYESTER

Simultaneous interpenetrating polymer networks (SIN) based on diglycid yl ether of bisphenol-A (DGEBA) and unsaturated polyester (UP) in weig ht ratios of 100/0, 50/50, and 0/100 were blended and cured simultaneo usly by using cumene hydroperoxide (CHP) and m-xylenediamine (MXDA) as curing agents. A kinetic study during SIN formation was carried out a t 43, 53, 58, and 64 degrees C. Concentration changes for both epoxide and C=C bond were monitored with Fourier transform infrared (FTIR). R ate expressions for epoxide polymerization were established with model reactions for phenyl glycidyl ether (PGE) and benzylamine in dichloro ethane containing benzyl alcohol. Experimental results revealed that a lower cure rate constant for the C=C bond during SIN formation was fo und, compared with pure UP network formation. A model of network inter lock is proposed to account for this phenomenon. During simultaneous c ure of DGEBA and UP, the network interlock should provide a sterically hindered environment, which subsequently retards cure rate for UP. On the other hand, epoxide cure during SIN formation indicates higher ra te constants for both uncatalyzed and catalyzed reactions, compared wi th those of pure DGEBA cure. Presumably the catalytic effect of hydrox yl end groups in UP overcomes the effect of network interlock. Kinetic parameters were calculated and are discussed. (C) 1995 John Wiley and Sons, Inc.