H. J. Wintle

Bio: H. J. Wintle is an academic researcher. The author has contributed to research in topics: Thermal conduction. The author has an hindex of 1, co-authored 1 publications receiving 95 citations.

Decay of Static Electrification by Conduction Processes in Polyethylene

Abstract: The theory of the transfer of charge from an electrified surface layer through the bulk of a dielectric is developed for transient space‐charge‐limited current conditions. The modifications required when conduction is included and when diffusion is included are indicated. Comparison with published data for polyethylene indicates carrier mobilities of the order of 10−11 cm2 V−1 sec−1 at room temperature.

Corona charging of polymers

Abstract: A review of the corona charging of polymers is presented. After providing a brief account of the corona discharge process and of its application for charging materials, the paper focuses on the evolution of corona triodes that allow the sample surface potential to be monitored during the charging process. Particular emphasis is given to the main contributions arising from research, basically on Teflon FEP and ferroelectric polymers, in which a constant-current corona triode was used. Such a triode system has become a powerful tool in the study of charge transport and ferroelectric properties of polymers, because keeping the charging current constant facilitates matching of the experimental results to a number of theoretical models. >

Surface‐Charge Decay in Insulators with Nonconstant Mobility and with Deep Trapping

Abstract: The motion of space charge initially located at the free surface of an insulator is studied as a function of time. Analytic results are given for the following cases: (a) mobility proportional to a power of the field; (b) mobility proportional to a power of the free‐carrier concentration; and (c) fast deep trapping which goes to completion. After one transit time, the surface voltage becomes a unique function of time, independent of its initial value. The available experimental data for polyethylene do not fit these simple models, and the discrepancies are discussed. It is also shown that the observation of thermally stimulated currents in thin‐film electrets implies that they are electrically inhomogeneous.

Electrodes and charge injection in low-density polyethylene using the pulsed electroacoustic technique

Abstract: The effects of electrode materials on space charge formation in low-density polyethylene (LDPE) have been investigated experimentally using the pulsed electroacoustic (PEA) technique. Common electrode materials used in either the laboratory or power cable industry were selected, i.e. aluminum, gold and carbon loaded crosslinked polyethylene (XLPE), and space charge accumulation after the application of high electric stress was monitored. Experimental results demonstrated that charge injection processes take place in all cases once the applied stress has exceeded a threshold. However the amount of charge, and the polarity of the dominant injected charges showed a significant dependence on the electrode materials under the same applied electric stress.

Charge Transport in LDPE Nanocomposites Part I—Experimental Approach

Abstract: This work presents results of bulk conductivity and surface potential decay measurements on low-density polyethylene and its nanocomposites filled with uncoated MgO and Al2O3, with the aim to highlight the effect of the nanofillers on charge transport processes. Material samples at various filler contents, up to 9 wt %, were prepared in the form of thin films. The performed measurements show a significant impact of the nanofillers on reduction of material’s direct current (dc) conductivity. The investigations thus focused on the nanocomposites having the lowest dc conductivity. Various mechanisms of charge generation and transport in solids, including space charge limited current, Poole-Frenkel effect and Schottky injection, were utilized for examining the experimental results. The mobilities of charge carriers were deduced from the measured surface potential decay characteristics and were found to be at least two times lower for the nanocomposites. The temperature dependencies of the mobilities were compared for different materials.