Naval Research Laboratory,
Keywords: phthlonitrile, resin, resorcinol
Summary:Improvement in Processing Parameters of 2nd Generation PEEK-like Composites for Advanced Applications Stephen M. Deese,1 Matthew Laskoski2 1 ASEE Post-Doctoral Researcher 2 Acting Section Head, Advanced Materials Section, Code 6127 U.S. Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375, USA A new oligomeric 2nd generation resorcinol, PEEK™-like phthalonitrile resin has been developed via cost-effective methods and is being transitioned to an industrial scale. The phthalonitrile monomer used to prepare composite components exhibits better processing viscosities relative to the 1st generation resorcinol-based phthalonitrile and is comparable to current resin technologies at their respective processing temperatures. When postcured to elevated temperatures, the composite exhibited excellent mechanical, dynamic mechanical, thermal, and flammability properties over a large temperature range. Postcured composite densities center around 1.60 g/cm3 with a 60-65% fiber volume fraction. After exposure to elevated temperature oxidative aging, the composites exhibited very low weight loss and high mechanical strength retention. The new phthalonitrile resins are optimized for facile insertion into industrial-scale composite production as they are cost effective, produce quantitative yields, and are easily scalable. Tailoring of the polymer backbone structure through simple insertion of various adjuncts allows for variation in the mechanical, thermal and chemical properties of the composite to be achieved. When fully cured, the composites exhibit no Tg which translates to minimal loss of structural integrity at elevated temperatures. Additionally, the composites display excellent thermo-oxidative resistance, low flammability, good dielectric, and low water absorption properties. References: 1. “Improved Synthesis of Oligomeric Phthalonitriles and Studies Designed for Low Temperature Cure” Laskoski, M; Neal, A.; Keller, T. M.; Dominguez, D. D.; Klug C. A.; Saab A. P. J. Poly. Sci. A Poly. Chem., 2014, 52, 1662-1668. 2. “Oligomeric Bisphenol A-Based PEEK-Like Phthalonitrile - Cure and Polymer Properties” Keller, T. M.; Dominguez, D. D.; Laskoski, M. J Poly Sci Part A Poly Chem, 2016, 54, 3769-3777. 3. “Synthesis of and Curing Additives for Phthalonitriles” Keller, T. M.; Laskoski, M., No. 8,981,036; issued March 17th, 2015.