Thermokinetics of unsaturated polyester and vinyl ester resins

An experimental study was carried out to investigate the isothermal and non‐isothermal curing kinetics of unsaturated polyester and vinyl ester resins, using differential scanning calorimetry (DSC). Emphasis was put on investigating the effect of low‐profile additives on the curing kinetics of the thermo‐setting resins. For the study, a general‐purpose polyester resin and a vinyl ester resin were used, together with polyvinyl acetate (PVAc) as low‐profile additive, benzoyl peroxide as initiator, and N,N‐dimethyl aniline as promoter. It has been found that (1) the addition of the low‐profile thermoplastic‐additive decreases the rate of cure and, also, the final degree of cure of the resins, (2) the total heat of cure generated by isothermal cure is lower than that generated by non‐isothermal cure, and (3) the resin/initiator mixture with promoter exhibits two major exotherm peaks during non‐isothermal cure, but only a single exotherm peak during isothermal cure.