Epoxy-methacrylate, chemical structures

Vinyl ester resins (VERs, epoxy methacrylates) are a major class of styrenated, free radically curable, corrosion- and chemical-resistant thermoset resins. They are largely used in fiber-reinforced structural applications, and they have a substantial history of long-term service in numerous environments at elevated temperatures and pressures, usually under load. 

Vinylesters are unsaturated, hence thermosetting, resins, prepared by the reaction of a monofunctional unsaturated acid, e.g. methacrylic, acrylic, crotonic or cynnamic acid, with a bisphenol diepoxide. This type of structure is referred to as bisphenol-A epoxy vinyl ester (Fig. 4.3(a)). The structural difference, which at least partially justihes the improved chemical and mechanical properties of vinylester, is the presence in vinylesters of reactive double bonds at the ends of the chains only, while unsaturated polyester resins have the reactive double bonds distributed throughout the chains. 

Comparison of a PS-PMMA blend with a corresponding copolymer gave information on the chemical drift. In the analysis of a competitive modified vinyl polymer sample by SEC/FTIR, some of the components of the binder could be readily identified (vinyl chloride, ethyl methacrylate, acrylonitrile), and an epoxi-dized drying oil additive was also detected. An analysis of styrene-butadiene copolymers, including a determination of the styrene/butadiene ratio and of the micro structure of the butadiene units cis/trans, l,2-/l,4-units), was performed by Pasch et al. 

In VE resins, the ester bond is located at the end of each polymer chain and results exclusively from the reaction of an unsaturated monocarbonic acid with the epoxy group of an epoxy resin. The reactive points have a methacrylate or acrylate structure and are located at the end of the polymer chain. Due to the methyl group branching of the methacrylic acid, the ester bond has spatial protection against hydrolytic and chemical attacks, which explains its high chemical resistance. 

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