Triazine Elastomers

Three technically feasible routes have now been established for preparation of linear perfluoroalkylene triazine polymers. The most advanced route is based on addition polymerization of long chain fluorocarbon dinitriles and diamidines, followed by acylation and cyclodehydration to triazine polymer. Large research samples have been made, but crosslinking to thermally stable vulcanizates is still a problem. An alternate method, active halogen elimination from a difunctional fluorotriazine monomer, has been, demonstrated. High molecular weight polymer has been formed, but it is not elastomeric at room temperature. The low temperature flexibility is a function of structure and not of the method of polymerization, therefore other monomers with longer fluoroalkyl groups hold promise of elastomeric products. The route has attractive economics, but elastomeric products with crosslinking capability must be demonstrated. Coupling of diiodofluoroalkyl triazine monomers employing ultraviolet radiation has been demonstrated. This route is not being pursued because of research required and the predicted high cost of monomer preparation, when compared to the previous two routes. Evaluations of compounded vulcanized triazine elastomer show excellent resistance to hydrocarbon fuels and hydraulic fluids at 370° C and to long term air aging at 300° C. Tensile strength is in the 500 psi range, but is expected to improve with closer control of molecular weight and branching of the polymer. Excellent prospects are in view for fuel tank sealants, wire insulation and elastomer components for hydraulic systems useful in the 300° to 400° C range.