Effect of gas counter pressure on the carbon fiber orientation and the associated electrical conductivities in injection molded polymer composites

Abstract

Abstract Polymers filled with conducting fibers to provide electrical conductivity performance have received great attention due to the requirements of many engineering applications. In the present article, injection molding of acrylonitrile butadiene styrene (ABS)/carbon-fiber composites using applied gas counter pressure (GCP) was conducted and the overall fiber orientation and associated through-plane electrical conductivity (TPEC) of each layer (core, shear and skin layers) and various locations (far gate, center and near gate) were characterized. Results show that GCP had significant effects on the fiber orientation and skin layer thickness, resulting in decreases in the fiber orientation level (FOL) value in all locations and TPEC increases with increasing GCP in the core region of the molded composites (improvement of 62% when 100 bar GCP was applied). However, the effect of increased skin layer thickness in reducing TPEC was stronger than the effect of decreased FOL in raising TPEC when GCP was applied. This resulted in the overall TPEC falling slightly with increasing GCP. The results also show that the electrical conductivity followed the sequence of far gate>center>near gate and the FOL followed the order of core layer<shear layer<skin layer. The results obtained in this investigation reveal the potential application of GCP technology associated with mold temperature control in injection molding to manufacture products with enhanced electrical conductivity in the future.