Electrical resistivity of polymers

Abstract

Measurements of the temperatwe dependence of volume resistivity of a variety of polymers are used to elucidate polymer structure and the mechanism of electrical conduction ne of the more important measurements made by 0 those investigating high polymers is that of the magnitude and temperature dependence of the electrical volume resistivity. Such data can be used to calculate the activation energy, E,, for the electrical conduction process in the polymer and to estimate the extent of polymerization. The magnitude and temperature dependence of the electrical resistivity (or conductivity) of a polymer is a function of the molecular structure of the polymer, the nature and number of the current carriers, and the temperature. Resistivity determinations have been used for many years by physicists in studying the structure of both elements and inorganic compounds (1), and more recently they have been applied to solid organic compounds ( 2 ) . However, the use of this measurement on high polymers has not been widespread. A number of years ago studies by Fuoss (3) and by Baker and Yager (4) utilized the temperature dependence of the resistivity as an aid in studying the molecular structure of polymers. Following their work, use of the technique has slowly become more widespread. However, the literature still does not contain any significant amount of accurate data on the magnitude and temperature dependence of the electrical resistivities of thermoplastic and thermosetting polymers. Such information is of great importance not only in technological applications of these materials but also in theoretical investigations. The values reported here and the experimental technique are of interest to those considering the possibility of employing modified polymers (5) as organic semiconductors. These data could also serve as an index for the characterization of polymers. In addition to the experimental work and data reported here, the available literature values for the temperature dependence of the resistivity of various polymers are also included. TheoreticalThe theoretical basis for calculating the activation energy, E,, of the electrical conduction process has been developed by Glasstone, Laidler, and Eyring ( 6 ) who have shown that the concepts used in chemical kinetic 80 studies can be successfully applied to physical processes. The change in the electrical resistivity of a polymer with temperature can be considered to be a rate process similar to those encountered in chemical kinetic studies and the same equations can be applied to both chemical and physical rate processes.Equation ( 1 ) is used to calculate the activation energy for the conduction process.where p is the resistivity, A, is a temperature independent constant, R is the molar gas constant 1.987 cal/degmole, T is the absolute temperature, and E, is the activation energy for the conduction process. Many investigators have studied the electrical conduction process in high polymers, (3, 7) and the evidence is that conduction is an ionic process. Ions stem from t...

Electrical Resistivity and Crosslinking in Thermosetting Resins

“…for 24 hours. This increase, however, is much smaller than was obtained by Warfield and Petree (1961).…”

“…This work was taken up after the war by Fineman and Puddington, who studied the cure of phenolic resins (1947a) and of resorcinol-formaldehyde and polyester resins (1947b). Warfield and Petree subsequently measured the polymerization of diallyl phthalate (1959), epoxy (Warfield, 1958;Warfield and Petree, 1961), polyurethane (1961), and polyester (1961) systems and achieved a rough qualitative correlation between the logarithm of the resistivity of the epoxy resin and the infrared absorption due to the epoxy groups at 915 cm.-1. Magee and Rotariu (1960) found a correlation between the change in the intensity of the infrared peak, due to the epoxy group, and the change in the logarithm of the resistivity of epoxide polymers during cure.…”

Analysis of the epoxy polymerization process with piperidine as the initiator

“…Therefore the electron mobility must be enhanced by the chemical potential field. Volume resistivity measurements were made by Warfield and Petree 6 where they assumed that the polymerization rate was proportional to the maximum rate of change of the logarithm of the resistance. Activation energies of the order of 17 kcal were found and the 14,000 cal per equivalent epoxy for the aliphatic/polyamine system studied.…”

Volume Resistivity of Viton Polymer under Thermal Aging

“…However, the critical volumetric concentration of the polymeric materials fillers has been the key interest since resistivity decreases when the filler fractions increase [ 4 , 5 , 6 ]. The magnitude and temperature dependence of a polymer’s electrical resistivity is a function of its molecular structure, the nature and number of the current carriers, and the temperature [ 7 , 8 ]. Theoretical and experimental efforts have been continuously developing polymers filled with carbon black in the applications of discharging static electricity and electrical shielding.…”