Low temperature cure of vinyl ester resins

Vinyl ester resins are well known for their versatility as a composite matrix. With the development of a promising room temperature molding technology, vacuum-assisted resin transfer molding, e.g. Seemann Composite Resin Infusion Molding Process (SCRIMP), the processability of vinyl ester resins at low temperatures has attracted considerable attention from the composite industry. The objective of this paper is to provide a better understanding of the reaction kinetics of this resin system at low temperatures. In this study, a differential scanning calorimeter (DSC) coupled with a Fourier transform infrared (FTIR) spectrometer was employed to measure the reaction profile of a vinyl ester resin with different promoter and styrene contents. A kinetic model based on the free radical co-polymerization mechanism was developed for simulating the reaction rates and conversions of styrene vinyl and vinyl ester vinylene groups. The model parameters were determined from several FTIR experiments under isothermal conditions. This model, in conjunction with heat transfer analysis, was able to successfully predict the temperature profiles during curing in two SCRIMP molding cases based on groove type resin distribution system.