Chemical Engineering Transactions (Jun 2013)
Curing and Decomposition Behaviour of Cresol Novolac Based Vinyl Ester Resin
Abstract
Vinyl ester resins were prepared from o, m, p-cresol epoxy novolac resin and methacrylic acid in the presence of triphenyl phosphine as catalyst and hydroquinone as polymerization inhibitor. The vinyl esterresin samples having acid value of ~ 7 mg of KOH/g of solid thus obtained were characterized by Fourier transform infra red spectroscopy (FT-IR) and Proton nuclear magnetic spectroscopy (1H-NMR). Samples were prepared at 30 °C from o-cresol novolac epoxy vinyl ester resin using styrene and methyl-methacrylate, respectively as reactive diluents. The curing behaviour of these samples in the presence of benzoyl peroxide (2 phr) as initiator was studied using Differential Scanning Calorimetry (DSC). The sample prepared from o-cresol epoxy novolac was found to be the more reactive than the sample prepared from m and p-cresol epoxy novolac during curing in the presence of styrene as reactive diluent. These samples were cured isothermally at 90 ± 2 °C for 2 hours. The decomposition behaviour of all these samples was studied by thermo gravimetric analysis (TGA) at a heating rate of 10 °C min-1. It was observed that vinyl ester resin based on o-cresol novolac epoxy containing styrene gave a more thermally stable product than the methyl methacrylate probably due to presence of aromatic ring.