Thermal conductivity of unidirectional fibre composites made from yarns and computation of thermal conductivity of yarns

Abstract

Measurement of thermal conductivity of fibre composites made from different fibre assemblies (yarns) consisting of apparel, industrial and high performance fibres is described. From the measured thermal conductivity values of compos ites, the computation of longitudinal and transverse conductivity of yarns is reported. The thermal conductivity of yarn along its axis is much higher than the thermal conductivity in transverse direction for all types of fibres, except E-Glass, showing that the phenomenon of thermal conductivity of fibres is anisotropic in nature. The behaviour of E-Glass in conducting the heat

is close to isotropic. Polyethylene filament yarn shows the highest anisotropy followed by Vectron, Kevlar, Technora, linen, high-tenacity polyester and jute. For the fibres of same chemical structure, high-tenacity fibres have slightly higher longitudinal and lower transverse thermal conductivity values compared to apparel-grade fibres. Industrial-grade polyester and nylons have high anisotropy in conducting heat than the apparel-grade fibres. The effect of fibre chemistry on the thermal conductivity of fibres is predominant than the effect of orientation of the molecules.