Polarity contact angle measurements

The dispersive and polar parts of the surface energies were calculated from contact angle measurements with test liquids of different surface tension and polarity, using a modified Wihelmy technique [79] Organoclay filler yF = + = 24.3 mJ m + 1.0 mJ m 2 EPDM = I = 24.2 mj... 

A series of membrane materials have been tested for the performance of water removal from hydrazine, including poly(vinyl alcohol) (PVA), ethyl cellulose, PS, and ABS (93). Contact angle measurements served to estimate the hydrophilic or hydrophobic properties. Apolar materials showed higher separation factors than polar materials. Encouraging results with respect to the performance were obtained with modified ethyl cellulose and ABS membranes. 

The three EME coupling agents in Table 1 were analyzed using contact angle measurements to determine their polar and dispersion components of surface tension. From the surface tension data, wettability envelopes were constructed and compared with the surface tension properties of the epoxy coating [4], These data predicted that EME 47 would be wet by the epoxy, but not EME 23. This is believed to be the reason for the very low peel strength when EME 23 was employed [4],... 

In order to achieve the above objectives, three vinyl acrylic latexes of varying butyl acrylate content have been prepared and cleaned1 for use in the study. Several anionic and nonionic surfactants commonly usod in emulsion polymerization have been used to investigate the effects of surfactant structure and polymer composition on the solubilization process. Polarity of latex surface estimated from contact angle measurements have been used to study the effect of polymer polarity on surfactant adsorption. 

Polarity of Vinyl Acrylic Latex and Surfactant Adsorption Contact angle measurements, dispersion and polar contribution to latex film surface tension and polarity of polymer calculated according to the method of Kaelble (10) of the three latex films are whown in Table V. It is seen that the polarity of the latex film decreases with increase in butyl acrylate content of the vinyl acrylic co-polymer. The polarity of the 70/30 (VA/BA) latex is very similar to that of the polybutyl acrylate homopolymer estimated to be about 0.21 (1). ... 

POLARITY OF LATEX SURFACE BY CONTACT ANGLE MEASUREMENTS (17)... 

The polarity and adsorption data discussed above reveal some interesting aspects of the surface chemistry of vinyl acrylic latex surfaces. It is quite likely that the polarity of the latex films, expecially of the two co-polymers, determined by contact angle measurements may not correspond exactly with their respective latex surfaces in the dispersed state due to reorientation of polymer chains during film formation. But the surfactant adsorption data shows clearly that the three latex surfaces in their dispersed state do exhibit varying polarity paralleling the trend found from contact angle measurements. The result also shows that the surface of the co-polymer latex surface is a mixture of vinyl acetate and acrylate units. This result is somewhat unexpected in a vinyl acrylic latex, prepared by a batch... 

The wettability of a polymer film normally is determined by static contact angle measurements. The surface free energy (SE) of a polymer can be determined by wettability measurements with two different liquids. The dispersion force and polar contributions to SE, 7 d and 7 p respectively, are also calculated normally by using the Owens and Wendt, and Kaelble methods [146,147], The measurements of contact angles (CA) on a given solid surface is one of the most practical ways to obtain surface free energies. 

To reduce these effects, LDPE samples were cross-linked by e-beam irradiation and then subjected to the photosulfonation process. Compared to standard LDPE, crosslinked LDPE displayed a higher content of — SO3H groups and higher surface polarity after photosulfonation. This was evidenced both by zeta potential and contact angle measurements. It is thus demonstrated that sample pretreatment by crosslinking provides more stable surfaces which maintain their polar properties during water contact. This is explained by a lower amount of extractable components as a result of radiation-induced network formation. 

Van Oss CJ, Good RJ, Busscher RJ. (1990). Estimation of the polar surface tension parameters of glycerol and formamide, for use in contact angle measurements on polar solids. / Dispers Sci Technol 11 75-81. 

Contact angle measurements provide information on the wettability of the sample, the surface energetics of the solid, and the interfacial properties of the solid-liquid interface. The samples were immersed in water and captive air and octane bubbles were determined by measuring the bubble dimensions. By measurement of both air and octane contact angles the surface free energy (.y) of the solid-vapor ( > ) interface may be calculated by use of Young s equation and the narmonic mean hypothesis for separation of the dispersive and polar components of the work of adhesion. This method for determination of surface and interfacial proper-... 

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. 

At the polymer surface the radical species (Scheme 6, steps 1 and 2) can react with atmospheric moisture to form surface hydroxyl groups (shown in step 3). The existence of polar groups, like -OH, at the surface is clearly shown in the contact angle measurements where a decrease of the water contact angle is detected (Fig. 13). In the XPS measurements an increase of the oxygen content is revealed (Figs. 17, 18), which confirms a surface oxidation of the polymer. 

Contact Angle Measurements, were obtained with a Drop Shape Analysis System DSA100 (Kriiss GmbH, Hamburg, Germany) using water and diiodomethane as test liquids. The contact angles were measured by the sessile drop method within two seconds. The surface tension y as well as the dispersive and polar components (yD and yp) were calculated based on the Owens-Wendt method [7],... 

Available surface free energies for cellulose derivatives are even scarcer than solubility parameters (Table 9). The total surface free energy was generally assimilated to the surface tension of a polymer solution in the range of concentration independence, whereas the non-polar and polar contributions were obtained from contact angle measurements. 

Figure 4. Method of determining y of polar liquids by contact angle measurements...

Just as polydienes and polyolefins have been modified in solution, they have also been surface-modified. For example, polar functional groups have been introduced to syndiotactic 1,2 polybutadiene surfaces by photolytic addition of thiols, as well as treatment with aqueous permanganate. Such si ace functionalization leads to changes in wettability, as evidenced by contact angle measurements. Furthermore, the surface functionalization can be reconstructed upon heating. In turn, polyolefins have been surface modified by oxidation, chlorination, sulfonation, etc. °... 

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