Chemistry and properties of vinylester resins as matrix materials

5 Chemistry and properties of vinylester resins as matrix materials 

This section is devoted to describing the chemistry of vinylester resins (including polymerization reactions) along with their mechanical, thermal and chemical (corrosion resistance and dimensional stability) properties. In general, vinylester resins are deemed to combine the best properties of epoxies and unsaturated polyesters in particular, they are easily handled at room temperature, and offer mechanical properties comparable to epoxy resins (Table 4.2). Moreover, they have better chemical resistance than cheaper 

Resin type Density (g/cm= ) Tensile strength (MPa) Tensile modulus (GPa) Flexural strength (MPa) Flexural modulus (GPa) Elongation (%) 

3 Polymerization structures of vinylester resins (a) bisphenol-A epoxy vinylester resin (b) novolac epoxy vinylester resin. 

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. 

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