Epoxy Resin || Some important Polymers || UG PaathShaala #epoxy
Channel: PaathShaaala
Date: 01/05/2021

Epoxy resin is a group of thermosetting polymers. Epoxy resins, also known as polyepoxides, are a class of reactive prepolymers and polymers that contain epoxide groups.
Epoxy resins may be reacted (cross-linked) either with themselves through catalytic homopolymerization, or with a wide range of co-reactants including polyfunctional amines, acids (and acid anhydrides), phenols, alcohols, and thiols (usually called mercaptans). These co-reactants are often referred to as hardeners or curatives, and the cross-linking reaction is commonly referred to as curing.
The reaction of polyepoxides with themselves or with polyfunctional hardeners forms a thermosetting polymer, often with favorable mechanical properties and high thermal and chemical resistance. Epoxy has a wide range of applications, including metal coatings, use in electronics/electrical components/LEDs, high tension electrical insulators, paintbrush manufacturing, fiber-reinforced plastic materials, and adhesives for structural and other purposes.

Most of the commercially used epoxy monomers are produced by the reaction of a compound with acidic hydroxy groups and epichlorohydrin. First, a hydroxy group reacts in a coupling reaction with epichlorohydrin, followed by dehydrohalogenation. Epoxy resins produced from such epoxy monomers are called glycidyl-based epoxy resins. The hydroxy group may be derived from aliphatic diols, polyols (polyether polyols), phenolic compounds or dicarboxylic acids. Phenols can be compounds such as bisphenol A and novolak. Polyols can be compounds such as 1,4-butanediol. Di- and polyols lead to diglycid polyethers. Dicarboxylic acids such as hexahydrophthalic acid are used for diglycide ester resins. Instead of a hydroxy group, also the nitrogen atom of an amine or amide can be reacted with epichlorohydrin.
The other production route for epoxy resins is the conversion of aliphatic or cycloaliphatic alkenes with peracids: In contrast to glycidyl-based epoxy resins, this production of such epoxy monomers does not require an acidic hydrogen atom but an aliphatic double bond.
The epoxide group is also sometimes referred to as an oxirane group.
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