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.

The goal of this research is to investigate the impact of the three parameters on the cure of the unsaturated polyester resin. The obtained values show the influence of each parameter on the cure and hence enables to establish a time-range with regard of the percentage of the components for a good management of the curing process.

In this study, the properties of unsaturated polyester resin were studied in the presence of recycled ceramic waste particles. Herein, composites were created that contained 28.5-50 wt% porcelain particles (particle size [180 �m). High filler contents increased the gel time and decreased the exotherm temperature of unsaturated polyester resin during curing. The obtained results showed that physical parameters, such as the resin density and porosity, increased as the filler content increased. In addition, the X-ray diffraction results indicated that the produced samples were a combination of ceramic waste particles and unsaturated polyester resin, resulting in semi crystalline structure. The results showed that the maximum water absorption at 40�C increased from 0.97 to 1.5% as the filler content increased from 28.5 to 50 wt%; in this process, the materials experienced a color change but did not lose mechanical performance. Finally, the samples were characterized by thermogravimetric analysis (TGA) to study the effect of porcelain powder on the thermal degradation of the resin. The TGA scans were analyzed with the Friedman method. The results indicated that the samples with porcelain powder exhibited substantially better thermal stability than unsaturated polyester resin.

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