Surface energy corona discharge

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. 

Corona discharge, bombardment of the wool fibre surface with electrons of sufficient energy to break covalent bonds, has also been applied to the improvement of shrink... 

Atmospheric corona discharge has been used to increase the surface energy of wood surfaces by oxidative activation (Back and Danielsson, 1987). Improved bonding of a water-based acrylate lacquer was found following corona treatment of the wood surface, with no improvement found when a solvent-based alkyd system was used. 

As with metallic substrates, primers may be used to protect treated nonmetallic substrates. After surface treatment, a high-energy substrate has an active surface that will readily adsorb atmospheric contamination. The primer protects the treated surface until the time when the adhesive or sealant is applied. Primers are especially useful in this way for the protection of polymeric parts that are treated by flame or corona discharge. Primers also find benefit on polymeric substrates in that their solvents will soften the surface, and some of the primer resin will diffuse into the bulk of the substrate, thereby increasing the adhesive strength by molecular diffusion. 

FEP resins have a very low energy surface and are, therefore, very difficult to wet. Surface preparation for improved wetting and bonding of FEP can be done by a solution of sodium in liquid ammonia or naphthalenylsodium in tetrahydrofurane [44] by the exposure to corona discharge [45] or to amines at elevated temperatures in an oxidizing atmosphere [46]. 

Table I gives a summary of the sources of energy on the earth s surface today (7). It is probable, therefore, that solar energy must have made the principal contribution to the synthesis of organic compounds in primordial times. Next in importance are electric discharges, such as lighting and corona discharges from pointed objects. These occur closer to the earth s surface and, hence, would have more effectively transferred...

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