Study On Cure Of Unsaturated Polyester Initiated By Complex Initiation

Unsaturated polyester resin (UP) as irreplaceable kind of thermosetting resin because of its high mechanical properties, weather resistance, low cost, and good resistance to chemical corrosion and so on, are widely used in various fields. In recent years, with the rapid development of SMC and BMC, unsaturated polyester resin as the matrix FRP composite materials gets more and more attention. However, the mechanism of curing system, especially the complex initiation mechanism of the system, as yet inconclusive.In this paper, tert-butyl peroxide (TBPB)/peroxide octanoate (TBPO) complex initiation system and TBPB/promoter complex initiation system were studied. The effects on gel time and curing time of curing system were compared by DSC and activity analyzer instrument, Single peak kinetics and dual-peak kinetics were applied to TBPB/TBPO initiator system, while Kamal model and modified Kamal model were used to fit the experiment data of TBPB/promoter system. Curing kinetic parameters were obtained by different models. BMC was made to study the molding gel time, flow resistance, storage stability, the bending strength, impact strength and Barcol hardness analysis. When content of TBPB was2%, content of promoter was2%, system had the best overall performance:bending strength was108MPa; impact strength was24.5Mpa; Barcol hardness was54HBa; gel time was30s; liquidity was168-193mm.In this paper, microcapsule was introduced to curing system. In situ polymerization method was used to prepare powdered urea-formaldehyde microcapsules which had thermosetting urea-formaldehyde resin as coating and TBPO as core. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to analyze and characterize the structure and morphology. DSC and thermal gravimetric analysis (TGA) were used to study the heat resistance and curing behavior. The results showed that: the microcapsules had dense and complete morphology, which melting point can be adjusted by the ratio of raw materials, pH value and the rotational speed. The curing process can be found that microcapsules had protection of the core material.