Dilek Kumlutaş

Thermal conductivity of particle filled polyethylene composite materials

In this study, the effective thermal conductivity of aluminum filled high-density polyethylene composites is investigated numerically as a function of filler concentration. The obtained values are compared with experimental results and the existing theoretical and empirical models. The thermal conductivity is measured by a modified hot-wire technique. For numerical study, the effective thermal conductivity of particle-filled composite was calculated numerically using the micro structural images of them. By identifying each pixel with a finite difference equation and accompanying appropriate image processing, the effective thermal conductivity of composite material is determined numerically. As a result of this study, numerical results, experimental values and all the models are close to each other at low particle content. For particle content greater than 10%, the effective thermal conductivity is exponentially formed. All the models fail to predict thermal conductivity in this region. But, numerical results give satisfactory values in the whole range of aluminum particle content.

Effect of Particle Shape on Thermal Conductivity of Copper Reinforced Polymer Composites

Thermal conductivity of copper powder filled polyamide composites are investigated experimentally in the range of filler content 0-30% by volume for particle shape of short fibers and 0-60% by volume for particle shapes of plates and spheres. The thermal conductivity of polymer composites is measured by the Hot-Disk method. It is seen that the experimental values for all the copper particle shapes are close to each other at low particle content, φ<10, as the particles are dispersed in the polyamide matrix and they are not interacting with each other. For particle content greater than 10% by volume, a rapid increase occurs in the thermal conductivity for the copper fibers filled polymer composite. As a result of this study, thermal conductivity of copper filled polyamide composites depends on the thermal conductivity of the filler particles, filler particle shape and size, and the volume fraction and spatial arrangement of the filler particles in the polymer matrix.

A Numerical and Experimental Study on Thermal Conductivity of Particle Filled Polymer Composites

In this study, thermal conductivity of particle filled polymer composites is investigated numerically and experimentally. In the numerical study, the finite-element program ANSYS is used to calculate the thermal conductivity of the composite by using the results of the thermal analysis. Three-dimensional models are used to simulate the microstructure of composite materials for various filler concentrations at various ratios of thermal conductivities of filler to matrix material. The models used to simulate particle filled composite materials are cubes in a cube lattice array and spheres in a cube lattice array. A modified hot wire method is used to measure the thermal conductivity of the composites consisting of a high-density polyethylene (HDPE) matrix filled with tin particles up to 16% by volume. The experimentally measured thermal conductivities are compared with numerically calculated ones by using the spheres in cube model and also with the already existing theoretical and empirical models. At low particle content, up to 10% of volume content of tin filler, numerical estimation and all other models except for the Cheng and Vachon model, predict well the thermal conductivity of the composite. For more heavily filled composites there is an exponential increase in thermal conductivity and most of the models fail to predict thermal conductivity in this region.