EXPERIMENTAL STUDY OF ILSS FAILURE PERFORMANCE OF CARBON NANOFIBERS Z-THREADED CFRP DURING EXTREME HEAT EXPOSURE

Previously reported vertical UL-94 testing results showed that carbon nanofiber z-threaded carbon fiber-reinforced polymer (ZT-CFRP) laminates have significantly improved flame resistance capabilities compared to traditional carbon fiber-reinforced (CFRP) laminates. Shorter flame self-extinguishing times and no flame propagation were reported. These characteristics provided evidence that ZT-CFRP’s unique microstructure, combined with its inherent strengthened mechanical, thermal, and electrical properties, has the potential to have more favorable high-temperature applications than traditional CFRP. This study examined the interlaminar shear strength (ILSS) enhancement of ZT-CFRP laminates, in comparison to traditional CFRP, when exposed to gradually increased temperatures. This was accomplished through the use of a furnace and an in-house constructed three-point bending apparatus capable of supplying static loading to determine the temperature at which failure occurred. The apparatus was loaded with a specimen and then placed inside the furnace where the temperature was allowed to increase based upon a consistent heating schedule. It was observed that ZT-CFRP samples had an approximately 30 ˚C improvement in temperature handling capabilities while exposed to an interlaminar shear load when compared to CFRP samples. Microscopic image analysis was also performed to observe how CNF z-threads contributed to the improved performance observed for ZT-CFRP at extreme elevated temperatures.