GOALI: Novel Flame Retardant Phenolic-Epoxy Resins Processable via Rapid Fabrication Methods

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9903672RifflePolymer matrix composites are potential alternatives to steel and concrete for civil and industrial structures such as tunnels, mass transit facilities, bridges, chemical and processing plant facilities, off-shore oil drilling rigs, etc. where light weight and long term corrosion resistance are major needs. One major obstacle, however, limiting the use of organic materials in public structures is their flammability. There are currently no polymer matrix candidates which meet the combined requirements of non-flammability, good toughness and strength, processability into continuous fiber reinforced composites by cost effective, rapid methods such as pultrusion or pressure injection molding, and low materials' costs. Phenolic resins are high volume materials widely utilized for many purposes, including structural adhesives, composites, coatings, etc. They are also well known to provide fire resistance in many applications. Pilot studies have demonstrated that the reaction of selected high functionality phenolic novolac oligomers with a stoichiometrically deficient amount of a diepoxide can produce void free, relatively tough, flame retardant, tough, phenolic-epoxy thermosets from precursors processable into composites by rapid continuous processes, and to investigate the relationships between chemical structure and flame performance of their composites. The research will be conducted jointly between researchers at Virginia Tech and the Dow Chemical Co. Particular features include: (1) Development of new epoxy crosslinking reagents containing phoshpine oxides and polysiloxanes for improved fire resistance without the use of halogenated aromatics (which lead to toxic smoke generation), (2) A study of the generation of controlled novolac oligomers with selective endgroup reactivity for preparing tough, void-free, phenolic-epoxy networks with minor amounts of the epoxy components, (3) Development of latent nucleophilic catalysts to tailor curing kinetics for continuous processing operations, notably pultrusion and rapid pressure injection, (4) A fundamental study of the relationships between chemical and network structure, and mechanical properties and flame resistance, and (5) The generation of continuous fiber reinforced composites to study relationships between resin properties and composite properties, including residual strength measurements after exposure to controlled burning to evaluated damage progression kinetics.Cost effective, non-flammable polymer composites could fill a critical need for structural components in buildings, transportation, and other construction projects where confined spaces make rapid evacuation in case of fire impossible. This approach could also be used to pre-fabricate components for efficient on-site construction. Particular needs exist in off-shore oil platforms, navy topside structures and submarines, mine shafts, and mass transit facilities where both lightweight and reliable structural performance are essential. This research addresses the development and fundamental understanding of lightweight, flame retardant materials, their incorporation into structural composites, and their performance in a fire.