Non-uniformity of the filler concentration and of the transverse thermal and electrical conductivities of filled polymer plates

The thermal and electrical properties of polymers can be improved by filling them with metallic particles. In practice, especially for mixtures of thermoplastic with metallic fibres, we observed a non-uniform distribution of the properties in the volume of the moulded part, as well as some similarity between the distributions of electrical and thermal conductivities, and between them and the distribution of the filler concentration. The amount of particle is greater far from the gate and also on both sides, the flat moulded piece being depleted near the gate and at its centre. In addition, tests on parts with two different types of aluminum fibre have shown that the non-uniformity of thermal and electrical conductivities can be reduced by decreasing the particle diameter.