How can the high temperature resistant resin react without dehydration?
(1) an open loop connection between epoxy groups;(2) the epoxy group reacts with a hardener with an active hydrogen functional group to crosslink;(3) the reaction between an epoxy group and an aromatic or aliphatic hydroxyl group in a hardener;(4) the epoxy group or hydroxyl group reacts with the group of the hardening agent to crosslink.
Different kinds of hardening agents have different roles in hardening. Some hardening agents do not participate in this molecule in the process of hardening and act only as a catalyst, such as inorganic substances. Amines, alcohols, phenols, etc. that have a single reaction group, such agents are called catalysts. Most hardening agents are involved in macromolecular reactions during hardening, forming part of a hardened resin, such as polyamines containing a reactive group, polyols, and multicomponent anhydrides.
The principle of hardening reaction of epoxy resin is not perfect at present. According to the different curing agent, it is generally considered as thermosetting product through the reaction of four ways.
