Study on rheological behavior of vinyl ester resin during thickening

With excellent mechanical property, thickening and curing performance, vinyl ester resin (VE) has been widely used as a resin matrix of sheet molding compound (SMC). The rheological behavior of vinyl ester resin during thickening process was investigated by rotational rheometer. It showed that the initiator affected the rheological behaviors of the resin significantly, which should be inhibited by rapid thickening rate. By introducing the gel point for thickening process, the optimization principle of thickener was established. Both single thickeners cannot meet the thickening requirement considering their thickening mechanisms which were confirmed by Fourier infrared spectrometer (FTIR). Complex thickener was proposed with its optimal ratio determined as 1.2% MgO to 3.0% TDI by the optimization principle. It was demonstrated that complex thickening system had excellent performance in thickening and antithickening behaviors as well as extended storage life of more than 60 days. J. VINYL ADDIT. TECHNOL., 24:239–247, 2018. © 2016 Society of Plastics Engineers