Curing of pultruded unsaturated polyester resin curing is linear macromolecules through the role of cross-linking agent, the formation of a three-dimensional body network, but the curing process and not consumption resin in all active double bond and reached 100%. That is to say, the curing of the resin is very difficult to achieve completely. The reason lies in the late curing reaction, the viscosity of the system increases sharply, which makes the diffusion is hindered. Generally only according to the material performance tends to be stable, it is considered to be cured completely. The curing degree of the resin has a great influence on the properties of glass fiber. The higher the degree of curing, the mechanical properties and physical and chemical properties of glass fiber reinforced plastic products have been fully played. (some people have done experiments, physical performance tests at different stages of UPR resin after curing. The results show that the bending strength increased with time and increasing until a year later did not become stable.
There are many factors that affect the curing degree, the composition of the resin itself, the amount of initiator, the amount of accelerator, curing temperature, curing temperature and curing time can affect the curing degree of polyester resin.