A. van Roggen

The Effect of Electrode-Polymer Interfacial Layers on Polymer Conduction

The tunneling model for electrical conduction of ultrathin polymer films with morphologically different layers is shown to be valid. The effect of barrier structure, i.e. thickness and potential profile, and that of the electrode work function and Fermi energy, are discussed.

The use of electric field meters for precision measurements

The largest class of electric field meters is that of the rotating vane, or vibrating probe, type. These meters measure the electric field by the charge induced on a sensor plate. Sensitivity is enhanced by varying this charge periodically, either by shielding the probe with a rotating or sliding shutter, or by modulating the capacitance of the probe, for example, by vibrating it. Although the physical construction and sophistication of these meters can vary greatly, they all register this modulated probe charge.

Distributions of Relaxation Times and Their Diagrams

A comparison is made between several distribution functions of dielectric relaxation times, their corresponding frequency-dependent permittivities, and the resulting Argand diagrams. For each family of distributions, the shape of the Argand diagram changes only slowly with the parameters in the distribution. In most cases, rigorous procedures are necessary before a distribution function can be uniquely determined from experimental data.

The electronic behavior of polymer surfaces

Transfer of electrical charge between two touching solid bodies is a common electrostatic phenomenon. There is, nevertheless, a controversy about the cause or causes that determine the polarity as well as the amount of charge transferred under given conditions. The controversy stems partially from a scarcity of theoretical work, and partially from an overabundance of experimental work the conclusions of which are debatable because the measured systems were not kept under rigid control or were not sufficiently varied to exclude different conclusions. It is hoped that the recent work by the ASTM on standard methods of testing for electrostatic charge will help to lift the controversy. This paper will describe the instrument as designed for solids, and will give some conclusions based on measurements made with this instrument.

Rapid dielectric permittivity measurements at microwave frequencies

The measurement of the real and imaginary components of the dielectric permittivity of a material at microwave frequencies usually involves the determination of phase shift and amplitude change in the Roberts-von Hippel technique1, or the perturbation of resonance in a cavity.2 Disadvantages of the former technique include the complicated mathematics necessary to solve the equations of the system, while the latter technique has only limited application for low-loss materials and requires a careful match between sample shape and cavity. A third method utilizes a traveling-wave probe in the specimen. Although this eliminates most of the mathematics of the Roberts-von Hippel method, it is seldom used because it applies to liquids only. Its accuracy suffers from the necessity of mechanical position measurements, made more difficult by the simultaneous need for seals as well as perfect alignment of the probe. A variation of the technique3 uses a fixed position probe and a variable-length liquid cell.

Review of electrostatic phenomena

First, an historic review will be given of early electrostatic experiments, and the attempts at theories describing electrostatic charging will be discussed. Modern theory had to await the development of thermodynamics, ionic solution theory, and of solid-state physics before charging phenomena relating to liquids and solids could be quantitatively understood.