THERMAL-CONDUCTIVITY AND DIFFUSIVITY OF HIGH-STRENGTH POLYMER FIBERS

The thermal conductivity kappa and diffusivity alpha of high-strength and high-modulus crystalline polymer fibers (polybenzobisoxazole (Zylo n(R)) and polyethylene (Dyneema(R))) and their fiber-reinforced plasti cs (FRPs) were measured in directions parallel and perpendicular to th e 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 sc attering over the temperature range of 10-260 K. From the analyses usi ng a phenomenological model, the thermal conductivity anisotropy ratio (kappa(parallel to)(fiber)/kappa(perpendicular to)(fiber)) estimated to be 80 at 100 K, which was about two or three times larger than that of Dyneema fiber.