TOUGH, VOID-FREE FLAME RETARDANT PHENOLIC COMPOSITES: PROCESSABILITY AND PROPERTIES

摘要

Void-free phenolic networks have been prepared from the reaction of phenolic novolacs with various epoxides. The new void-free Systems had significantly improved mechanical properties over commercial novolac networks. Cone calorimetry was used to investigate the heat release rates and other parameters, and the new systems were found to be comparable in fire resistance to typical phenolics, while maintaining the superior mechanical characteristics of epoxies. The kinetics of the phenolic/epoxy systems have been investigated as a function of catalyst structure and concentration. These results are being used for developing latent catalyst systems, in which the catalysts are encapsulated in a polymeric sizing material to enable melt processing by methods such as pultrusion. A series of linear, controlled molecular weight cresolic novolac resins have also been investigated to further optimize structural properties as well as processing conditions. These more sterically hindered phenolics may reduce the inherent reaction between phenol and epoxy at melt processing temperatures leading to wider processing windows.