Carbon fiber epoxy-matrix composites with hydrothermal-carbon-coated halloysite nanotube filler exhibiting enhanced strength and thermal conductivity

The incorporation of hydrothermal-carbon-coated halloysite clay nanotube (HNT/C) as a filler in continuous carbon fiber polymer-matrix composite is reported. The HNT/C (0.9 vol% of the fiber composite) with 11.9 vol% carbon enhanced the flexural strength and storage modulus by 18% and 23%, respectively, and decreased the porosity from 4.4% to 0.9%. The strengthening is due to the reduced porosity, effective filler dispersion, and strengthened filler-matrix bond resulting from the interaction between epoxy and the amine-functionalized hydrothermal carbon. The filler addition increased the through-thickness thermal conductivity by 149%. The ductility was unaffected. The glass transition temperature was decreased slightly.