HIGH PERFORMANCE EPOXY-MODIFIEDPHENOLIC FOAMS

摘要

Phenolic foams have been widely used in a variety of applications including aircraft, civilrnconstruction and electronic applications. They exhibit outstanding flame, smoke, andrntoxicity (FST) properties, good insulation properties, and low production costs. However,rnphenolic foams are brittle and friable compared to other foams used for sandwich cores.rnThese properties have severely limited most structural applications, and presently limitrnthe use of phenolic foams to insulating applications. In recent work, an epoxy-modifiedrnphenolic foam (E-P foam) was developed by crosslinking the phenolic with epoxy resinsrn[1]. E-P foams exhibit markedly improved properties compared with pure phenolicrnfoams. This work is focused on the development and characterization of E-P foams withrnvarious kinds of epoxy resin. Four different epoxy resins were used for this approach.rnOne is a regular diglycidyl ether of bisphenol A (Epon 826) type. A second epoxy usedrnis a brominated bisphenol A (542) to further improve the FST properties of the resultingrnfoams. The third is a bisphenol F based epoxy (Epon 862) to enhance the reactivity andrnmechanical performance. The final epoxy is resorcinol diglycidyl ether (Erysis RDGE)rnfor its high purity. On the basis of the cone calorimeter test results, the flame resistancernproperties of the epoxy-phenolic foams modified with different types of epoxy resin arerndiscussed. The mechanical (compression and shear strength and modulus) properties arernevaluated and compared with competing commercial foams.