CHARACTERIZATION OF UNSATURATED POLYESTER RESIN CURED WITH STYRENE

In this work, the curing kinetic of an unsaturated polyester resin, mi xed with styrene as curing agent, was studied by means of diffential s canning calorimetry (DSC) and infrared (IR) spectroscopy. Investigatio ns were made in situ during curing and post-curing periods. The enthal py (Delta H-cop) characterizing the styrene homopolymerization and its copolymerization with the polyester chains was determined from isothe rmal DSC investigations. The residual enthalpy (Delta H-res) was deter mined from nonisothermal DSC measurements. We find that the quantity ( Delta H-res + Delta H-cop) depends on the curing temperature (T-iso). Styrene homopolymerization and/or copolymerization lead to characteris tic bonds modifications. The variations of the most characteristic bon ds versus curing duration were studied from Fourier transform IR inves tigations. The data allow the determination of a relationship between transformation rate and curing duration using a time constant (tau) ch aracteristic of each reaction involved during the liquid to solid-stat e transformation. (C) 1998 John Wiley & Sons, Inc.