Enhancing the through-thickness thermal conductivity of carbon fiber polymer-matrix composites by nanostructuring the interlaminar interface

Heat dissipation from aircraft is important. Carbon fiber polymer-matrix structural composites have high in-plane thermal conductivity, but low through-thickness conductivity. A nanostructuring method involving carbon black at the interlaminar interface was developed to improve the through thickness conductivity. Ethylene glycol monoethyl ether (EGME) was the vehicle for dispersing the carbon black and for partial dissolution of the epoxy resin on the fiber-epoxy prepreg surface. EGME evaporated from the prepreg surface prior to composite fabrication. The optimum carbon black content in EGME for attaining high through-thickness conductivity was 0.8 wt. % for both unidirectional and crossply configurations. EGME applied without carbon black improved the conductivity by up to 36%. For EGME with carbon black, the improvement was up to 210%. For the same interlaminar interface modification (except for 1.2 wt.% carbon black), the conductivity and its fractional increase were higher for the crossply configuration than the corresponding unidirectional configuration. The through-thickness compressive modulus and the flexural modulus were increased by up to 14% and 11% respectively by using EGME with carbon black. The average thickness of the interlaminar interface increased with increasing carbon black content, but it was decreased by the use of EGME alone.