Aligned CNT Reinforcement of High-Temperature Polymer-Matrix Composites

Composites are often used in aerospace applications due to their superior specific strength and stiffness properties, as well as their resistance to fatigue and corrosion. While tensile properties are dominated by fibers, many other properties such as shear, delamination toughness, impact resistance are matrix-dependent.  Further, few composites are used in propulsion system components—where they could provide significant weight and maintenance savings compared to current metallic counterparts—due to their service-temperature requirements. High-temperature polymers such as Polybismaleimide (BMI) have shown promise in composite laminates, however exhibit low interlaminar strength. Through prior STTR work with the Navy, Metis Design Corporation and MIT have demonstrated the use of aligned carbon nanotube (CNT) to effectively reinforce interlaminar regions between composite plies with no added weight or thickness. These investigations have not only shown improvements in static properties, but as much as a 5x improvement in fatigue life. The proposed Phase I effort would follow a similar experimental path as our prior CNT reinforcement efforts, however focusing on Carbon/BMI laminates.  Testing will focus on interlaminar properties (such as SBS strength) in static and dynamic loading compared to unreinforced laminates.  The Phase I option would aim to address scaling and integration into common manufacturing environments.