Electric discharge treatment

The work on electrical discharge treatment and derivatisation was carried out in collaboration with Dr. A.R. Blythe and Mr. C.R. Kendall (ICI). The work on monofunctionalisation of polyethylene is the postgraduate thesis work of Miss A. Chew, part of a collaborative project with Dr. D.M. Brewis and Dr. R.H. Dahm of Leicester Polytechnic. 

Fig. 1. Schematic diagram of the electrical discharge treatment process...

Fig. 12. Installation for electrical discharge treatment in electrolyte 1 - workpiece,...

Fig. 13. Microstructure of recast layer obtained by electrical discharge treatment in electrolyte of HS 6-5-2 steel, x800.

The thickness and integrity of obtained recast white layer on the steel surface by electrical discharge treatment in electrolyte depend on the electrical current characteristics and time duration of the treatment. At higher voltage are observed thicker white layers by equal... 

Krastev, D., Yordanov, B. (2010). About the Surface Hardening of Tool steels by Electrical Discharge Treatment in Electrolyte, Solid State Phenomena, Vol. 159 (February 2010) pp 137-140, ISSN 1662-9779... 

Other approaches have been to graft itaconic acid to PP [49] and PE [50] acrylic acid to PE after corona treatment [51] maleic anhydride to PP [52] acrylamide to PP after electrical discharge treatment [53] ... 

Blythe AR, Briggs D, Kendall CR, Ranee DG, Zichy VJI. Surface modification of polyethylene by electrical discharge treatment and the mechanism of autoadhesion. Polymer 1978 19 1273. 

Adberabibty of the film may be enhanced by its treatment with flame, electric discharge, boron trifluoride gas, activated gas plasma, dichromate sulfuric acid, and a solution of alkab metal ia Hquid ammonia (84—87). A coating of polyurethane, an alkyl polymethacrylate, or a chlotinated adhesive can be apphed to PVF surfaces to enhance adhesion (80,88,89). 

Electric discharge (corona, cold plasma) is another method of physical treatment. Corona treatment is one of the most interesting techniques for surface oxidation activation. This process changes the surface energy of the cellulose fibers [28]. In the case of wood surface activation it increases the amount of aldehyde groups [291. 

Rajanikanth, B.S. and Ravi, V. (2002) Pulsed electrical discharges assisted by dielectric pellets/catalysts for diesel engine exhaust treatment, IEEE Trans. Diel. El. Insul. 9, 616-26. 

The simplest analytical method is direct measurement of arsenic in volatile methylated arsenicals by atomic absorption [ 11 ]. A slightly more complicated system, but one that permits differentiation of the various forms of arsenic, uses reduction of the arsenic compounds to their respective arsines by treatment with sodium borohydride. The arsines are collected in a cold trap (liquid nitrogen), then vaporised separately by slow warming, and the arsenic is measured by monitoring the intensity of an arsenic spectral line, as produced by a direct current electrical discharge [1,12,13]. Essentially the same method was proposed by Talmi and Bostick [10] except that they collected the arsines in cold toluene (-5 °C), separated them on a gas chromatography column, and used a mass spectrometer as the detector. Their method had a sensitivity of 0.25 xg/l for water samples. 

The modification of the chemical composition of polymer surfaces, and thus their wettability with chemical substances, can be realized in different ways electric discharges more commonly called Corona effect, oxidation by a flame, plasma treatment, UV irradiation and also UV irradiation under ozone atmosphere. Numerous studies have been devoted to the effects of these different treatments. More recently, Strobel et al. [204] compared the effects of these treatments on polypropylene and polyethylene terephthalate using analytical methods such as E.S.C.A., F.T.I.R., and contact angle measurements. They demonstrated that a flame oxidizes polymers only superficially (2-3 nm) whereas treatment realized by plasma effect or Corona effect permits one to work deeply in the polymer (10 nm). The combination of UV irradiation with ozone flux modifies the chemical composition of the polymers to a depth much greater than 10 nm, introducing oxygenated functions into the core of the polymer. 

Some polymers do not swell or solve or show any adhesion with any type of adhesive, such as PE and PP, which can, therefore, not be joined by gluing. However, a very thin surface layer can be chemically modified by an electric discharge, or by strong etching chemicals, so that adhesion is enabled. Similar surface treatments are also applied to enable printing with paint or ink. 

PVF films often require a surface treatment to improve bonding to other materials. Among these are flame treatment,69 electric discharge,70 chemical etching, and plasma treatment.71... 

In most countries between 50% and 70% of the polyethylene film produced is sold in printed form, either on-the-reel or as bags. The preparative treatment used most frequently in this type of work is electrical discharge and a varied range of units for the purpose is available commercially—differing in design but... 

D 5999 D 6004 D 6005 D 6105 Test Method for Noninterference of Adhesives in Repulping Test Method for Determining Adhesive Shear Strength of Carpet Adhesives Test Method for Determining Slump Resistance of Carpet Adhesives Practice for Application of Electrical Discharge Surface Treatment (Activation) of Plastics for Adhesive Bonding... 

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