Preparation of elastomer-metal composites and investigation of conductivity properties

Composites are materials formed by the combination of more than one and insoluble materials in each others. It usually consists of a low strenght matrix main phase and reinforcement material dispersed in this phase. Polymers have been used as insulating materials in terms of conductivity for many years and these properties are being improved with various additives. Today, composite materials have been used since ancient times in many fields such as from automotive to aerospace industry, from home appliances and from maritime to defence industry. In this study, polybutadiene (PBD) was used as matrix material, and prepared CB/PBD and Metal Powder/CB/PBD composites which is containing different proportions of CB and metal powders by using zinc, copper, nickel powders and carbon black (CB) as reinforcing material. The resistance, conductivity, resistivity and conductivity properties of these prepared composites were investigated. Firstly, in order to determine whether time has an effect on the conductivity of the prepared composites, resistance measurements made both under pressure and without the effect of pressure were examined and it was observed that there was no change in electrical properties of the composites over the time. Evaluations were made by considering the type and amount of additives. As a result of the preliminary test measurements, while conductivity could not be achieved in Zn/PBD composites containing 40-50% Zn powder, up to the samples containing 43% Zn powder, conductivity could be achieved even at lower Zn contents with the addition of CB at different rates. Here, it can be said that CB acts as a compatibilizer with its synergetic effect. Pre-trial results are not included here. In the following studies, Zn, Cu, Ni metal powders were used as additives at a rate of 0-60% each, while PBD and CB were used at the same rate in each. While the electrical conductivity obtained with the samples prepared with Zn, Ni and Cu metal powders was observed as Cu>Ni>Zn, high resistivity values were obtained for the same amount of CB at low metal powder loading. In comparisons made with the aim of obtaining the most effective conductivity properties, it has been observed that metal powder filled composites exhibit electrical conductivity properties even when added in small amounts. The best results were achieved in composites containing Cu powder. While the thermal conductivity coefficient is expected to increase with increasing filler concentration, it has beed observed to decrease in Zn doped composites. While the thermal conductivity increased in Cu and Ni containing composites, it drew a constant curve starting from 40% metal filling.