Kinetic study on epoxy bisphenol-A diacrylate IPN formation

Interpenetrating polymer networks (IPN) based on diglycidyl ether of bisphe nol-A (DGEBA) and bishenol-A diacrylate (BADA) in weight ratios of 100/0, 5 0/50, and 0/100 were blended and were cured simultaneously by using benzoyl peroxide (BPO) and 4,4'-methylenedianiline (MDA) as curing agents. Kinetic study during IPN formation was carried out at 65, 70, 75 and 80 degrees C. Absorbance changes at 1623.3 cm(-1) and 914 cm(-1) relating to concentrati on changes of C=C and epoxide were monitored with Fourier-transform infrare d spectroscopy (FTIR). The epoxide cure kinetic data revealed a combination of non-catalytic bimolecular reaction and a catalyzed termolecular reactio n, while the C=C cure kinetic data fitted a first-order reaction. The calcu lated kinetic parameters indicated decreased rate constants and increased a ctivation energies of the IPN compared with those of the individual compone nts. Presumably, chain entanglements between the two networks provide a ste rically hindered environment for the cure reactions and vitrification restr ains the chain mobility, accounting for the kinetic parameters. (C) 1999 Society of Chemical Industry.