Scientists from the US Naval Research Laboratory (NRL) Chemistry Division have designed and developed a second-generation, cost-effective polyetheretherketone (PEEK) similar phthalonitrile-resin for several marine, aerospace and domestic applications.
Featuring superior high-temperature, flammability and low water absorption properties, the resin can be used to develop composite components using industrial methods such as resin0transfer molding (RTM), resin-infusion molding (RIM), filament winding and prepreg consolidation.
The organic compound can also be used for manufacturing parts by using automated composite manufacturing techniques, including automated tape laying and automated fibre placement.
NRL advanced materials section head Teddy Keller said that the fully cured phthalonitrile can be used for structural applications in oxidising and thermally hostile environments.
"A low-melt viscosity and a larger processing window exhibited exclusively by the new second generation phthalonitrile technology are useful for fabrication of thick composite sections where the melt has to impregnate into thick fibre preforms," Keller said.
NRL’s PEEK-like phthalonitrile resins also demonstrate dielectric permittivity and loss tangent characteristics for potential high-temperature radomes and other applications requiring radiofrequency transparency.
Additional features of the second-generation polymers include low-processing temperatures and superior thermo-oxidative stability at temperatures in excess of 3750 C.
Currently, the PEEK-like phthalonitrile is focused on applications including aircraft, ship, automotive, and wind blade structural applications, battery casings, fire-resistant textiles and structural composites, robotic and autonomous firefighting, and ammunition casings and storage containers.
The phthalonitrile-based polymers are expected to boost the use of composites in applications that range from lightweight automobiles to fire-resistant building materials.
Image: NRL’s phthalonitrile resins can be used in radomes, equipped onto E-2C Hawkeye aircraft. Photo: courtesy of Dod/US Navy.