Effect of residual stresses on the resistivity of injection-molded carbon-fiber filled polymer composites

In order to study the effect of the residual stresses on the electrical conductivity of injection-molded conductive polymer composites, authors, taking injection-molded carbon-fiber filled polymer as an experimental object, calculated the residual stresses of the moldings with layer removal method, and they have minor effect on the resistivity at the core area of the molding. The distribution of carbon-fiber in the matrix may be uniformed with the release of residual stress and the dynamic movement of molecular chain during annealing, which resulted in the decrease of the resistivity of the molding residual stresses and the resistivity of the moldings. Authors measured the fiber orientation with continuously tracking cross-section of the fiber and integrated such results measured into the residual stresses calculation to increase the reliability of the calculation. The results show that residual stresses mainly affect the resistivity at the skin area of the molding, because the continuity of conductive network is improved. The greater compressive residual stresses are at the skin area of the molding, the more the resistivity declines at such area after annealing because of faster dynamic recovery of molecular chains, and the better the electrical conductivity of the whole molding is. © 2014 Journal of Mechanical Engineering.