Fully aminated rigid-rod aramid reinforced high strength epoxy resin and its composite with carbon fibers

Poly(p-aminophenylene aminoterephthalamide) ((NH2)(2)-PPTA), a new organo-soluble fully aminated rigid-rod aramid has been synthesized by the polycondensation of nitroterephthalic acid and 2-nitro-1,4-phenylenediamine and then hydrogenation-reduction of the nitro side groups. (NH2)(2)-PPTA was then used as the modifier of epoxy resin (EP) and carbon fiber (CF)/EP composites and their mechanical properties were systematically investigated. Because all the benzene rings in (NH2)(2-)PPTA contain amino side groups, (NH2)(2)-PPTA has excellent solubility in organic solvents and EP. In addition, the amino side groups are able to react with the matrix so as to effectively integrate the rigid-rod (NH2)(2)-PPTA into the cross-linked molecular network of EP and facilitate the stress transfer between EP and (NH2)(2)-PPTA. The tensile and flexural properties and notch impact strength of EP are greatly increased with the addition of only 0.5 wt% (NH2)(2)-PPTA. Unusually high tensile strength and flexural strength have been achieved, which reach 140.6 & PLUSMN; 4.1 MPa and 237.9 & PLUSMN; 12.3 MPa, respectively. Moreover, addition of a small amount of (NH2)2-PPTA also significantly improves the flexural strength, toughness and the interlaminar shear strength of CF/EP composites. Compared with previously reported nanofillers and other rigid-rod polymers, (NH2)(2)-PPTA shows better reinforcing and toughening effect for EP and CF/EP composites owing to its great solubility, reactivity and inherent great mechanical properties.

Automated summary

Poly(p-aminophenylene aminoterephthalamide) ((NH2)(2)-PPTA), a new organo-soluble fully aminated rigid-rod aramid, has been synthesized and used as a modifier for epoxy resin (EP) and carbon fiber (CF)/EP composites. It shows excellent solubility and reactivity, and significantly improves the mechanical properties of EP and CF/EP composites.