MOLECULAR COMPOSITES BASED ON AROMATIC POLYAMIDES---SYNTHESIS AND CHARACTERIZATION; POLY(OXYVINYLENE)LACTAMS: NOVEL POLYMERS FROM N-(CHLOROACETYL)LACTAMS

Molecular composite materials were prepared using a novel in situ technique in which the polyanion of poly(phenyleneterephthalamide) (PPTA) was used as both the reinforcing agent and the polymerization initiator. A thermoplastic composite system based on Nylon 3 formed from the anionic polymerization of acrylamide and a thermosetting system based on the polymerization of epoxy resin were prepared. Up to 30 wt% PPTA could be incorporated into the Nylon 3 as a fine dispersion of molecules or microfibrils. These composites exhibited greatly improved tensile strength, modulus and heat resistance over unreinforced Nylon 3 without sacrificing elongation. The thermosetting epoxy system was used to compare the properties of a conventional fiber-filled composite system to the properties of a molecular composite system. The molecular composite exhibited significantly greater heat resistance than did the fiber-filled system at temperatures above the glass-transition temperature of the cured epoxy matrix. This is indication that the molecular reinforcement network is more effective in serving as tie molecules to support the polymer as it changes from a glass to a rubber.;A spin-off of this research was the discovery that N-(chloroacetyl)lactams of ring size 6, 7, and 8 would spontaneously polymerize to form poly(oxyvinylene)lactams. The postulated mechanism for this polymerization involves the self-addition of a mesoionic "isomunchnone" intermediate. This intermediate was trapped in 1,3-dipolar cycloaddition reactions, and the formed products represent a new class of 2-pyridone compounds.