Investigation of anisotropic thermal conductivity in polymers using infrared thermography

A new experimental method based on infrared thermography (IRT) is developed to study deformation-induced anisotropic thermal conductivity in polymers. An analytic solution for the temperature field of samples heated by a point source is utilized with a robust fitting procedure allowing for quantitative measurement of two components of the normalized thermal conductivity tensor of uniaxially stretched samples. In order to validate the method, we compare measurements on a cross-linked polybutadiene network with those obtained from a previously developed technique based on forced Rayleigh scattering (FRS). We find excellent agreement between the two techniques. Uncertainty in the measurements using IRT method is estimated to be about 2-5%. The accuracy of the method and its potential application to nontransparent materials make it a good alternative to extend current research on anisotropic thermal transport in polymeric materials.