Epoxy resins generalized synthesis reaction

Synthesis Epoxy resins consisting ofglycidyl ether, ester and amines are generally prepared by the condensation reaction between diol, dibasic acid or amine and epichlorohydrin in the presence of sodium hydroxide with the elimination of hydrochloric acid. The commercially available epoxy resins are, however, made by the reaction of epichlorohydrin and bisphenol-A. Cashew nut shell liquid (CNSL)-based novolac epoxy resins have also been reported [342]. 

Proper formulation of epoxy adhesives requires knowledge of the chemical reactions that lead to polymerization as well as the chemical and physical properties of both the uncured mixture and the cured material. This chapter reviews the general principles of epoxy resin chemistry including synthesis of the epoxy monomer itself and its possible polymerization reactions. 

A considerable number of detailed descriptions on synthesis, production, and applications of epoxy resins exists. Because the aim of this chapter is the application of cationic initiators, and more particularly photoinitiators, to the polymerization of epoxies leading to cross-linked products (curing reaction), only litterature dealing with these aspects will be cited. For the general aspects of epoxy resins the scientific and patent literature may be found in detailed reviews [119,120] and classical books [121-123]. 

Figure 3.2 (a) Epoxy resin synthesis generalized reaction (b) reaction of hydroxyl group of NaOH with proton (c) displacement of the chlorine atom by the hydroxyl group (d) chain propagation (e) termination step. 

Bisphenol-A (BPA) is an important raw material for the synthesis of polycarbonates, epoxy resins and other polymers as well as polymer additives. It is conventionally produced by acid-catalysed condensation of phenol with acetone. Application of various catalysts for the BPA synthesis is discussed with particular attention to the substrates conversion and the reaction selectivity. Recent developments in the BPA production and its applications are presented. Moreover, potential toxicological and endocrine disrupting properties of BPA are considered with the emphasis on human exposure, general toxicology, and biological effects. 

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