Epoxy Resin System Activating Agents

Asthma due to exposure to ethylene amines in manufacture has been reported by Dernehl (1951), and after exposure to aliphatic polyamine or epoxy resin curing agents (Dernehl 1963). Phthalic anhydride, often used in hot curing systems, is a recognised irritant of the respiratory tract and asthma has been reported (American Industrial Hygiene Association Journal 1967 Malten and Zielhuis 1964 Petit et al. 1961). 

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It should be pointed out that diluents are not the only way to lower the viscosity of filled epoxy resins systems. Surface active agents can also be added to the system. They provide better wetting of the filler by the epoxy resin matrix. This can lead to substantial viscosity reduction for systems having equivalent filler concentration. The surface active agent, in turn, could also be used to produce formulations with higher filler loading at equivalent viscosity. These surface active agents are discussed in Chap. 10. 

TGA/FT-IR and DSC/FT-IR were utilized in this research to characterize an amine activated epoxy resin system. The specific system under study was a near-monomeric diglycidyl ether of Bisphenol A (2-di-[4-(2,3-epoxy-l-propoxy)-l-phenyljpropane) with an epoxy equivalent weight of 173. The curing agent was composed of a mixture of 10% tertiary amine catalyst and 90% primary cycloaliphatic diamine. Cured and uncured systems were analyzed using these hyphenated techniques. 

The binder system of a plastic encapsulant consists of an epoxy resin, a hardener or curing agent, and an accelerating catalyst system. The conversion of epoxies from the Hquid (thermoplastic) state to tough, hard, thermoset soHds is accompHshed by the addition of chemically active compounds known as curing agents. Flame retardants (qv), usually in the form of halogens, are added to the epoxy resin backbone because epoxy resins are inherently flammable. 

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