Characteristics of thermoplastics containing electrically conducting asymmetric particles: Anisotropic electrical conductivity of injection molded parts and extrusion behavior

Abstract The characteristics of compounds of acrylonitrile‐buta‐diene‐styrene and high impact polystyrene resins, filled with carbon fibers, steel fibers, carbon black, and aluminum flakes have been investigated with special emphasis on electrical conductivity and flow behavior in a capillary rheometer. Compression and injection molded compounds were found to be highly electrically anisotropic. The components of the electrical conductivity tensor, K ₁₁ , K ₂₂ and K ₃₃ , were measured, Generally K ₁₁ , the flow direction conductivity, has the highest value and the thickness direction, and K ₃₃ has the lowest. The injection molded parts were usually electrically heterogeneous with the conduetivities highest at the greatest distances from the gate. The results were interpreted in terms of particle orientation and distribution. Shear viscosities were measurable for all but the aluminum flake compounds which exhibited fluctuating pressure drops. The flow of these compounds through dies was investigated. Examination of material from the die entrance indicated streamline flow without entrance vortices. Sometimes high entrance concentration of particulates were observed especially for the aluminum flakes. Extrudates were found to contain oriented particles.