UC San Diego

The focus of this research project was to design and build a steady state apparatus that could accurately measure the thermal conductivity of different materials. By modeling the experimental design with ASTM standards and taking care to reduce heat loss terms, a design was built that was able to accurately measure two reference materials (Pyrex and Stainless) to within 1% of their reference values. After verifying the experimental design, the thermal conductivity of the CNT RET polymer was determined and compared with 3-[omega] results. Both data sets from different thermal conductivity methods yield an increase in thermal conductivity with an increase in volume percent CNT. The results from 3-[omega] depicted a evident percolation of thermal conductivity as a function of volume percent as compared to a linear relationship from steady state results. These differences in the thermal conductivity could have been caused by differences in testing samples, such as CNT orientation. Variations in the locations of functional groups within the CNT and location of the CNT attachment to the RET polymer chain can vary significantly from sample to sample. As a result, the varying interfaces between CNT to CNT and CNT to polymer matrix can result in significant thermal interface resistances. Future work may include research into vertically aligned CNT thermal interface materials, specifically their interface characterization. A need for accurate steady state thermal conductivity measurements and a understanding of CNT polymer composites and CNT interfaces are crucial in developing future thermal interface materials (TIMs)