Study On Crosslinked Network/Curing Behavior And Properties Of Bisphenol A Epoxy/Novolak Resin

Phenolic resin has been widely used in the binding agent, a resin material and a wear-resistant composite materials because of its excellent flame retardancy,low price and good mechanical properties. We generally use the hexamethylenetetramine as curing agent of the thermoplastic phenolic resin. Because the benzene ring of cured phenolic resin is joined by the methylene, the density of rigid group is too large and the rotating freedom of chain segment is over low. This leads to the poor toughness of phenolic resin. Because it releases ammonia and water molecular in the reaction of the phenolic and hexamethylenetetramine, Volatiles will cause the networks to have high void contents. We use the epoxy resin instead of hexamethylenetetramine to cure thermoplastic phenolic. It will generate ether bond through the reaction between hydroxyl group of phenolic resin and epoxy group of epoxy resin and the phenolic resin is cured without releasing volatiles. These materials, in which high compositions of an epoxy resin have been cured with thermoplastic phenolic, have been used in microelectronic packaging applications.In this paper, we studied the effects of the type and amount of bisphenol A epoxy on cross-linked network and properties of novolac/BPA/PPh3system. Then on the basis of the above experiment, we add hexamethylenetetramine to the novolac/BPA/PPh3system to increase crosslink density. We study the Influence of the change of crosslinked network and crosslink density on system properties.It was found that crosslinked network,tensile strength, elongation at break and moisture resistance is improved with the increase of bisphenol A epoxy segment length and it has little change in the thermal decomposition capacity and the glass transition temperature is reduced.