Carbon nanotube reinforced polymers for multifunctional composite structures

In order to meet challenging multifunctional performance goals for composite missile structures, including Insensitive Munitions (IM) and electromagnetic interference (EMI) shielding, the Army is developing new composite materials with higher thermal and electrical conductivity. Conventional approaches in the development of thermally and electrically conductive polymers have involved the use of metallic particles or carbon black as fillers in the matrix. While these materials have achieved increased thermal conductivity and improved shielding effectiveness, the amount of filler material required to achieve the desired thermal and electrical conductivity properties have increased composite weight and raised viscosity to a level that prevents processing via conventional composite manufacturing processes, such as filament winding or resin transfer molding. This research has involved the development and characterization of a modified epoxy resin system with multiwall nanotube (MWNT) reinforcements. The Phase I research has demonstrated the ability to achieve increased electrical conductivity at relatively low MWNT concentration (MWNT) in a dispersed MWNT-reinforced epoxy resin and significantly higher through-thickness conductivity (up to 20 W/m-K) via epoxy-infiltrated, aligned MWNT arrays. The ongoing Phase II research involves more comprehensive material and process development and characterization, with larger scale component-level testing to integrate the material technology into representative composite structures.