A method for determining surface charge decay [Q(t)], using a coaxial cylindrical capacitor arrangement and an electrometer interfaced to a PC, has been adapted so as to perform relatively straightforward measurement of resistivity in the surface region of insulators. A charge transport model is presented, based on Mott–Gurney diffusion, which allows interpretation of the data especially for the initial phase of surface charge decay. Resistivity measurements are presented for glass, mica, plexiglas, and polyethylene, covering the range 109–1018 Ω m, as an illustration of the useful range of the instrument for static and antistatic materials, particularly in film or sheet form. Values of surface charge diffusion constants have also been determined for the materials.

A method and theory presented earlier by the authors, for the straightforward measurement of resistivity in the surface region of charged insulators, in the initial phase of charge decay, is demonstrated also to be valid for much longer time scales. This is achieved with the use of a theoretical charge transport model, enabling a direct comparison between experimental and theoretical data. This comparison enabled the accurate determination of both the diffusion coefficient (D) and the layer of surface charge (Δz). Results are presented for glass, plexiglas (perspex), and polyethylene covering a useful resistivity range in the insulator class. The surface charge transport behavior of small rectangular samples is also studied using this computational model, focusing on the potential and charge distributions involved. From this study, some insight is gained into the way the charge in the surface region of insulators decays away with time when one end of a charged sample is earthed. The method provides a ready means of measuring the resistivity, carrier diffusion coefficient, and carrier occupancy depth in surface charged insulators.

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This paper presents resistivity data for a range of surface‐grafted and copolymerized polymers and some challenges yet to be faced in resolving the effects of surface modification on their surface properties, in particular on electrical resistivity in their surface regions. The principal substrates used for measurement were polyaniline (PAN), low‐density polyethylene (LDPE) and polytetrafluorethylene (PTFE). Electrical resistivity has been determined as a function of graft monomer type (acrylic acid, sodium salt of styrene sulphonic acid and N,N‐dimethylacrylamide), graft temperature, grafting time and plasma pretreatment time. In the case of grafted PTFE, the effect of an emeraldine coating on resistivity is also determined. Copyright © 1999 John Wiley & Sons, Ltd.