A REVIEW OF MEASURING THE GELATION TIME IN UNSATURATED POLYESTER RESINS

Unsaturated polyester resins (UPRs) are commonly used as matrix resins for fiber-reinforced composites. During processing, the resins undergo a molecular cross-linking process called curing, during which they change irreversibly from viscous liquids to rigid and highly cross-linked polymer solids. The gelation time is critical for the success of a resin system, but it is difficult to measure accurately. It depends on several parameters. In this study, the parameters investigated are the effect of choice and their relative proportions. Parameters such as catalyst, accelerators, inhibitor, and fillers were examined. Various combinations of catalyst, accelerator, inhibitor, temperature and filler were analyzed to investigate the effect on the gel time of the unsaturated polyester resins. Then, this review assembles the scientific data on the gelation of unsaturated polyester resins to help readers better understand this process. Students, researchers, technologists, engineers, and chemists involved in the technology of synthesizing these monomers and polymers will benefit from this material.