Unsaturated polyester technology has become more and more mature with the development of production, and has gradually formed its own unique set of production, application theory and technical system.
(1) Theoretical aspects The theoretical progress of unsaturated polyester plays an important guiding role in promoting the improvement of production technology.
1 The understanding of the mechanism of polycondensation reaction in the synthesis of unsaturated polyester is of great significance for the reasonable determination of the staged reaction process and the acquisition of high quality products with uniform molecular structure. On this basis, different types of resin products such as meta-benzene type, bisphenol A type, and neopentyl glycol type have been produced, and the performance is improved.
2 The analysis, derivation and calculation of the average molecular weight and molecular weight distribution of polyester provide a theory for predicting and controlling the molecular weight of polyester polycondensation products.
3 The understanding of the gelation and curing mechanism of polyester is the basis for the successful determination of various FRP forming process conditions. All mechanized, semi-mechanized and hand-formed methods are determined to meet specific resin and gel and cure conditions. Conversely, different molding methods also place specific requirements on the gel and cure properties of the resin.
4 Research on the thickening mechanism of sheet molding compound (SMC) and the research results of the mechanism of low shrinkage and low profile additives overcome the technical difficulties in SMC production, and make polyester molding compounds enter large-scale, high-efficiency and low-cost. In the new stage of producing high-quality products, further promoted bulk molding compound (BMC), thick molding compound (TMC), high-strength molding compound (HMC), oriented fiber molding compound (ZMC), high-strength sheet molding compound (XMC) The development of other types of plastics.
5 The research on composite structure theory reveals the special mechanical properties of this kind of anisotropic materials, which leads to the structural design and calculation theory of composite materials, which provides an important guiding basis for practical production and application.
6 Research on the interface state of glass fiber and resin is of great significance to improve various physical properties and chemical properties of laminate materials. Accordingly, various coupling agent utilization techniques have been produced to significantly improve the performance of the composite material.