Anisotropy of electrical conductivity in doubly oriented nylon 66

Abstract

Abstract The electrical conductivity of doubly oriented nylon 66 has been studied as a function of direction over the temperature range 23–150°C. Measurements were made (a) along the chain axes, (b) along the hydrogen‐bonded planes perpendicular to the chain axes, and (c) perpendicular to the hydrogen‐bonded planes. A complicated dependence of conductivity on pretreatment was found. In general the conductivity over the whole temperature range was anisotropic, being least along the chain axes and, after a number of thermal cycles, greatest along the hydrogen‐bonded planes perpendicular to the chain axes. Below 120°C. the activation energy of conductivity was also anisotropic. At temperatures higher than 120°C. the temperature dependence is isotropic. The anisotropy of the activation energy and conductivity are explained in terms of activated mobility and structural parameters. Water vapor had a pronounced effect on the conductivity. It lowered the activation energy of conductivity while increasing the overall conductivity in an anisotropic manner. The conductivity along the chain axes was again less than that parallel and perpendicular to the hydrogen‐bonded planes. The activation energy of conductivity along the chain axes was equal to that parallel to the hydrogen‐bonded planes. The increase in conductivity caused by the adsorption of water was greatest along the chain axes. Four factors may contribute to the observed effects: (a) increased dielectric constant, (b) increased carrier concentration, (c) increased charge carrier path length, and (d) plasticization.