Electrical conductivity of iodine‐doped pseudo interpenetrating polymer networks of poly‐(carbonate‐urethane) and natural rubber

Abstract

AbstractRecent DC conductivity measurements on iodine‐doped full and psuedo IPNs of poly (carbonate‐urethane) (PCU) and natural rubber (NR) reveal that these materials possess a modest conductivity. Both such full and pseudo IPNs (with linear NR chains) are single‐phased materials if the NR is of sufficiently high molecular weight derived from Brazilian Manihot glaziovii. On iodine doping the electrical conductivity rises eight orders of magnitude of both the full IPN (to ca. 10−5S cm−1) and the pseudo IPN (to ca. 10−4 S cm−1). A simple theory based on the assumption that conduction occurs essentially along the linear NR chains, composing a percolation cluster, in the iodine‐doped pseudo IPNs of PCU and NR accounts for the observed electrical conductivity dependence on temperature, iodine molality, and weight fraction of NR. As temperature decreases the DC conductivity falls and the material becomes essentially an insulator. At sufficiently low temperature (ca. 115 K) this trend reverses and the DC conductivity rises by two orders of magnitude with further decreasing temperature up to that of liquid helium. © 1994 John Wiley & Sons, Inc.