Measuring and predicting in-plane thermal conductivity of carbon-filled nylon 6,6 polymer composites

In this study, two different carbons (synthetic graphite particles and carbon fiber) were added to nylon 6,6, and the resulting composites were tested for both the through-plane thermal conductivity k(thru) and the inplane thermal conductivity k(in), using the transient plane source method. The first goal of this work was to use a finite element model to develop a procedure to accurately measure the material properties using this relatively new analytical procedure. Reproducible data can be obtained for nylon 6,6 polymer composites, by choosing a power dissipation (an input parameter to the transient plane source method) corresponding to a sensor temperature increase of 2 K above the initial temperature after 5 s. The second goal of this work was to develop a simple empirical model for the in-plane thermal conductivity, which is easily measured with the transient plane source method. The results show that the product of the through-plane and in-plane thermal conductivities is a linear function of the volume percent phi. As the through-plane thermal conductivity of these composites is accurately predicted with a modified Nielsen model, this empirical relationship can be used to estimate in-plane thermal conductivities for a range of applications.