Zisman method critical surface tension

In summary, there are three basic approaches to use contact angle data to determine the surface tensions of solid surfaces. These approaches are the Zisman method, the surface tension component methods, and the equation of state. Within these three approaches, there are many variants. It is reasonable to wonder the merit, accuracy, and limitation of some of the methods. The Zisman method is an empirical approach based on the correlation between the cosines of the contact angles on a solid surface versus the surface tensions of the test liquids. With alkanes, linear plots are usually obtained, and the critical solid surface tension (yc) is determined by extrapolating... 

The surface energy (critical surface tension) of solids is measured by a method developed by Zisman.9 In this method a series of contact angle measurements are made with various liquids with known surface tensions on the solid to be tested. The contact angle 9 is plotted as a function of the yLV of the test liquid. The critical surface tension is defined as the intercept of the horizontal line cos 9=1 (i.e., when the contact angle is 0°) with the extrapolated straight-line plot of cos 9 against yLV of the liquids. The yLV at this intersection point (i.e., where a hypothetical test liquid would just spread over the substrate) is defined as the critical surface tension of the solid. 

An empirical method to estimate the surface tension of a solid is Zisman s plot (cos 9 as a function of yl), which obtains the critical surface tension of wetting. In the absence of specific interaction between the surface and the liquids used for the measurement of contact angles, the critical contact angle of wetting can be accurately estimated and its value used as the surface tension of the surface. However, if a surface interacts with liquids used as the sessile droplet for the contact angle measurement, to the extent that the surface tension is altered, Zisman s plots deviate from the ideal linear relationship. In a strict sense, the plot is applicable only to imperturbable surfaces with which liquid contact does not alter surface configuration, i.e., no surface dynamics applies. 

Critical surface tension of solids (Zisman s method)... 

Solid 7c Critical surface tension (mN/m) from Zisman plot 7s° Dispersion Component (mN/m) from Fowkes method 7s Surface Tension (mN/m) from Fowkes method... 

The use of a Zisman plot to determine the critical surface tension is relatively straightforward and has become a widely used method to characterize a low-energy solid with respect to the surface free energy. Table 6.3 gives the critical surface tension values for a number of common polymers, while Table 6.4 shows such values for various surface functional groups. The... 

Fox and Zisman first proposed the concept of critical surface tension in the early 1950s. In Zisman s method, the relationship between the contact angle of various liquids on a solid and the surface tension of the liquids are investigated. Specifically, cos 9 is plotted against yLv (known as Zisman plot) in which a straight line is often obtained when a homologous series of liquids are used to wet the solid s surface (non-linear for non-homologous liquids). 

Our studies showed that the inner surface of the cardiovascular System was hydrophobic surface with Yc(Zis.)=29 dyne/cm. We could easily select polytetrafluoroethylene as the material with a smaller critical surface tension than 29 dyne/cm to make test materials. Figure-3 shows the surface properties of the inner surface of the cardiovascular system and polytetrafluoroethylene in relation to wetting properties viewed from Zisman s plots. How should we treat polytetrafluoroethylene to minimize the difference in wetting properties between the surface of polytetrafluoroethylene and the inner surface of the cardiovascular system. We tried to improve the surface properties of polytetrafluoroethylene by using the graft copolymerization method and expansion method. 

Elemental and molecular surface chemistry plays an important role in the acceptance of an implant material [2-12]. In the study of the elemental and chemical composition of polymeric surfaces, XPS, secondary ion mass spectrometry (SIMS), and surface energy evaluations have emerged as the dominant methods for surface analysis. This is due to the ability of XPS to provide qualitative and quantitative elemental and chemical information (10-100 A), which is complemented by the molecular information obtained from SIMS over the outermost 5-25 A. Surface wettability measurements provide a rapid and quantitative measurement of the inherent surface wettability of a solid sample. When these measurements are accompanied by a Zisman plot, the polarity and critical surface tension (7. ) of the solid surface may be determined. The critical surface tension is a measure of the surface free energy (yj of solid materials. The surface morphology of the lenses studied here was investigated through the use of atomic force microscopy (AFM). The sensitivity of the technique allows submicrometer (to Angstroms) sized features to be examined. 

Several authors have tried to determine critical surface tensions for solid surfaces by determining the contact angles for a set of solutions of different concentrations. Zisman s method is, however, not applicable to solutions due to the large probability for specific and selective adsorption of the components constituting the solution. 

The various approaches motioned previously in this chapter can be used to estimate the surface tensions, e.g. of various polymers. Thus, polymer surface tensions have been reported using interfacial theories and contact angle data, from the critical surface tension (Zisman plot) and from extrapolating melt data to room temperature. There is relatively good agreement among the various methods for many polymers, within 4—5 mN m Some typical results are shown in Table 6.5. 

Table 15.3 shows components of surface tension for some solid polymers estimated by the Owens-Wendt methods the Zisman critical surface tensions values are also given. There is rather good agreement between the predicted polymer surface tensions from the Owens-Wendt and Zisman methods. 

Owens and Wendt (1969) report for PTFE (Teflon) contact angle measurements for water (108°) and for methylene iodide (88° and 77°, the latter with their own mcasiu-ements). Similarly, they report for PE contact angle measurements for water (94° and 104°, the latter with their own measrrrcments) and for methylene iodide (52°). Calculate the dispersion and specific contribution of the strrface tension of the two polymers using the OW method and compare the obtained solid surface tensions with the Zisman values of the critical surface tension which are 18.5 (PTFE) and 31 (PE). AU measurements arc at room temperature and all strrface tensions are in mN m. Provide a discussion of the results. 

Zisman and co-workers used the critical surface tension principle to correlate wettability with the constitution of low-energy surfaces. Condensed mono-layers were prepared on polished platinum or glass by adsorption from solution and isolation by the retraction method. Data obtained by these methods [26] are tabulated in Table 11.3. 

It is not permissible to adopt data acquired from changes of the liquid resin s surface tension for solid state polymer. Zisman [72] does it supposing that the reversible adhesion work of the solid polymer must be close to that estimated for the liquid state. The conclusion follows from the assumption that the forces that act on the phase separation boundary spread out to a depth that does not exceed the size of some molecules. As a result, the interaction on the bound y cannot depend on the change of state of the substance. One must accept this because the determined v dues of the surface tension of solid polymers significantly exceed those for the liquid oligomers. If we deal with undercured products the v dues usually exceed those for the polymer surface tension acquired by wetting agent critic d surface tension methods. 

The purpose of this chapter is to present the LAD performance experiments carried out in room temperature liquids. Bubble point and reseal pressure tests for a 325x2300, 450 X 2750, and 510 x 3600 Dutch Twill screen are conducted in storable liquids, methanol, acetone, IPA, water, and binary methanol/water mixtures of various methanol concentrations. First screen pore diameters are estimated based on analysis from scanning electron microscopy and historical data. Experimental results are used to compare methods for determining effective pore diameter. Next, contact angles are measured for both pure and binary mixture fluids using a modified version of the Sessile Drop technique. Then, the equation of state analysis from Neumann and Good (1979) is used to determine the critical Zisman surface tension for stainless steel LAD screens, which... 

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