A study on thermal characteristics of polymer composites
filled with micro sized tio2 particles

Abstract

This thesis reports on the research dealing with the processing and characterization of TiO2 filled polymer composites. The first part of the work includes the description of the materials used and the details of the experiments that are done during this research. It also presents the test results in regard to the physical, mechanical and micro-structural characteristics of the epoxy and polypropylene composites filled with micro-sized TiO2 particles. The second part depicts the development of a theoretical heat conduction model based on which a mathematical correlation has been proposed for estimation of effective thermal conductivity of polymer composites with uniformly distributed micro-sized particulate fillers. In this part, the correlation is validated for TiO2 filled polymers through numerical analysis and experimentation. The last part has reported on the epoxy and polypropylene composites in regard to their other thermal characteristics such as glass transition temperature (Tg) and coefficient of thermal expansion (CTE). The effects of TiO2 content on these properties of epoxy and polypropylene have been studied experimentally. The estimation of effective thermal conductivity of the composites using finite element method (FEM) and using the proposed theoretical models is done and the results are validated by corresponding experimental results. The findings of this research suggest that incorporation of TiO2 into epoxy and polypropylene leads to substantial improvement in thermal conductivity and glass transition temperature of the resins. At the same time, TiO2 helps in lowering the coefficient of thermal expansion of such composites. This work further shows that the FEM serves as a good predictive tool for assessment of thermal conductivity of these composites. The theoretical correlation proposed in this work can serve as a very good empirical model for spherical inclusions to estimate the effective thermal conductivity of the composites within the percolation limit. With light weight and improved heat conduction capability, the TiO2 filled polymer composites can be used for applications such as electronic packaging, encapsulations, communication devices, thermal interface material, printed circuit board substrates etc.