A review of the factors of delayed curing_heating of epoxy resin

Epoxy resins are widely used in the composite, aerospace, building, electronics, adhesive and coating industries due to their physical and mechanical properties as well as good thermal, electrical and chemical resistance. Epoxy resins require chemicals called curing agents or curing agents for curing. These materials affect the processing conditions and the final properties of the resin system. In general, epoxy curing agents can be classified into two groups: conventional curing (ambient curing or thermal curing) and delayed curing. Adding ordinary curing agents to the resin to perform crosslinking reactions even at ambient temperature causes a gradual increase in viscosity and eventually the resin is gelled and cured. However, the delay curing agents do not react after the resin is added at ambient temperature and the viscosity of the mixture does not change, therefore, epoxy resin is used for single component systems. These curing agents are not active under normal conditions and do not react with the resin. However, they are activated by the application of external stimuli such as light and heat. Since the most important external stimulus is heat, so delay cooking agents are one of the most widely used and common delay-heat cooking agents. Delayed curing agents include delayed curing agents containing active hydrogen, catalyzed and protected by chemical groups and microcapsules. Baking agents protected by chemical groups Baking agents contain ordinary active hydrogen which is protected by chemical groups. The choice of the type of delay system is an important issue and has a great impact on the processing conditions and the final properties of the cured resin. This article reviews the latest findings in this regard.

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