Thermal Conductivity and Diffusivity of High-Strength Polymer Fibers

Abstract

The thermal conductivity κ and diffusivity α of high-strength and high-modulus crystalline polymer fibers (polybenzobisoxazole (Zylon \circR ) and polyethylene (Dyneema \circR )) and their fiber-reinforced plastics (FRPs) were measured in directions parallel and perpendicular to the molecular chain axis of the fibers. The main contribution to thermal conductivity was from phonon conduction along the molecular chains in both fibers and the phonon conduction was limited by boundary-like scattering over the temperature range of 10–260 K. From the analyses using a phenomenological model, the thermal conductivity anisotropy ratio (κ // fiber /κ ⊥ fiber ) of Zylon fiber was estimated to be 80 at 100 K, which was about two or three times larger than that of Dyneema fiber.