Plate, used, surface energies

Before equations such as Eqs. 6, 7 and 8 can be used, values for the surface energies have to be obtained. While surface energies of liquids may be measured relatively easily by methods such as the du Nouy ring and Wilhelmy plate, those of solids present more problems. Three approaches will be briefly described. Two involve probing the solid surface with a liquid or a gas, the third relies on very sensitive measurement of the force required to separate two surfaces of defined geometry. All involve applying judicious assumptions to the experimental results. 

This same technique should be helpful in understanding wetting properties important in the oil industry since wetting is very dependent on mineral surface energies. The use of contact angle hysteresis information may allow a better understanding of the effects of surface heterogeneities of natural mineral samples. The dynamic Wilhelmy plate technique is ideally suited for such experiments ... 

Plates of glass, PTFE, dolomite and marble were used. Dolomite and marble were chosen because they represent minerals found in oil reservoirs. Glass and PTFE were investigated because they represent high and low surface energy solids respectively and are good model systems for data comparisons. Liquid/solid wetting cycles were obtained for each of the solids in the liquids listed in Table III. 

Electroless plating uses similar steps, but involves the deposition of metal on a metallic or non-metallic surface without the use of external electrical energy. 

The contact angle measurements were used in a computer program to obtain values of the surface energy of the plate and this value resolved into dispersion and polar components. This program was written using the equations proposed by Wu (19). Table 1 lists these values on the new plate before running on press. 

Low surface energy additives such as silicone oils have also been used to reduce toning, presumably by acting as a release layer between the ink and plate, since surface energetics alone would not predict its usefulness. 

By the laser treatment, the surface of PTFE films could be made hydrophilic and the surface energy increased in comparison with that of a native PTFE film. As the results, we intended to extend the hydrophilic modification technique into metallization on the PTFE film by using a chemical (electroless) plating technique. If the activators for the plating will deposit only on the hydrophilic region, area-selective metallization will be performed on the surface of PTTE films modified upon the laser-irradiation through a mask by a projection method. 

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