Thermal Conductivity of Needle Punched Preforms made of Carbon and OxiPAN Fibres

The thermal conductivity of preforms made by a needle punching technique has been measured using a tailor-made apparatus. Measurements were carried out in the absence of the matrix resin to find the thermal conductivity of the preforms themselves. The preforms were made with a variety of material compositions and textile structures, and various needle punching densities. Preforms made of woven fabric showed higher thermal conductivity than preforms of felt fabric. Needle punching density had a strong influence on the thermal conductivity. Increasing the needle punching density decreased the thermal conductivity along the in-plane direction, and increased it along through-the-thickness direction. The thermal conductivity in the through-the-thickness direction was about 30% to 50% of that in the in-plane direction, but the differences between the two directions decreased with increasing needle punching. An analytical model for thermal conduction in both directions was devised, and the results were consistent with those of experiments. The thermal conductivity of the rearranged fibres in the punching hole was estimated by parametric studies.