Water contact angle tests

In the water desorption test the VTES films on flamed silica proved to be more resistant to change than the VTES films on air-dried silica. This difference is illustrated by the data in Figure 7. On air-dried surfaces after one hour adsorption time the VTES produced a film that initially had a low water contact angle and was not significantly altered in the desorption experiment. By allowing 20 hours contact with the solution a more hydrophobic film was obtained but it was quickly desorbed to a condition equivalent to that for only an hour adsorption time. On flamed silica, in contrast, the film adsorbed after 20 hours adsorption time showed only a slight tendency to lose its hydrophobic character. 

Standard test method for corona-treated polymer films using water contact angle measurements, ASTM D5946-96. 

Table 4.4 Water drop contact angle test on plasma-treated metal surfaces [4], Proc SPIE 2009, reprinted with permission...

The polymer-metal interface between the ionic EAP and the embedded elec-trode(s) was significantly improved using plasma treatment. Based on the water drop surface contact angle tests and mechanical testing, oxygen plasma-treated stainless steel and titanium led to much better adhesion between the electrodes and the EAPs. For both stainless steel and titanium, XPS confirmed the presence of a... 

Figure 4 Relationship of polyarylate air-water contact angle with fibrinogen adsorption, (a) No overall correlation exists over all 46 tested polyarylates. (b) Examination by polymer substructure reveals correlations that are structure-dependent. Reprinted from Weber, N. Bolikal, D. Bourke, S. L. Kohn, J. J. Biomed. Mater. Res., Part A 2004, 68A (3), 496-503, with permission from Wiley.

ASTM D5946-96 Standard Test Method for Corona-Treated Polymer Films Using Water Contact Angle Measurement— This method covers the measurement of the contact angle of water droplets on corona-treated polymer film surfaces the results are used to estimate the film s wetting tension. 

Before actual bonding, the subjective water-break test or the quantitative and objective contact-angle test may be carried out. After bonding, the effectiveness of surface preparation may be determined by measuring the bond strength and determining the mode of the failure of the adhesive joint. 

The contact angles of water and formamide on test materials were measured using the sessile drop method with the contact angle test instrument JCC-1 made in China (Changchun Science Instrument Factory) at 20°C in air. The radius of the... 

In order to compare the agarose solution with water, contact angle measurements were carried out in the same way, using a KSV CAM200 contact angle meter, for both a 3% solution of agarose in deionised water, stirred at 70°C for 2 h and for pure deionised water heated to 70°C. The warm liquid was applied to the test surface in equilibrium with an atmosphere of 23°C and 50% rh. 

Gu et al. [23] used ozone to pretreat a Pellethane surface and later functionalized the surface with polyacrylic acid. The surface hydrophilicity of Pellethane thermoplastic polyurethane ( TPU ) is significantly improved by showing a much lower water contact angle (CA 25° vs 92° of pure Pellethane TPU, for CA test, please see Section 2.2) The COF of the modified surface was as low as 0.1. 

As noted above, PMTFPS exhibits somewhat surprising surface properties. According to our measurements, its liquid surface tension is higher than that of PDMS, its critical surface tension using n-alkane contact angle test liquids is similar to the PDMS value, while its solid surface tension judged by the Owens and Wendt [10] approach with water and diiodomethane liquids has a value considerably less than that of PDMS. 

However, whether bipolar plates need to be desirably hydrophobic or hydrophilic to avoid water flooding, is a long-lasting and ongoing discussion and is not intended to be answered in this chapter. But to assure either one surface property or the other over the period of operation, water contact angle measurement is a quick and simple testing method and is to be conducted. 

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