The Effect of Biaxial Orientation on the Thermal Conductivity of Vulcanized and Unvulcanized Rubber

Abstract

Abstract Experiments have been carried out to investigate the effect of equibiaxial orientation on the thermal conductivity of a series of natural rubber compounds. The conductivity was measured normal to the direction of stretch. The main effect has been explained quantitatively and an equation obtained which relates the conductivity to the extension ratio. The effect of orientation is not only of intrinsic interest but is also technologically significant, since the conductivity can decrease by a factor of 4 for quite modest extension ratios. The size of the effect indicates that it should be taken into account in mixing and extrusion theories, since in such processes the orientation is comparable to or greater than that of our experiments, but so far all theories have ignored any possible change in the thermal transport properties. We have also observed that crosslinking causes a significant decrease in the thermal conductivity.