Plots, Zisman

2 Wetting and adhesion via the Zisman plot and theories for interfacial tensions 

There are two important approaches for studying wetting phenomena the Zisman s plot and the associated concept of the critical surface tension and the use of interfacial theories. These two approaches are presented in this section. The approach based on interfacial theories is somewhat more complex but provides more information. When combined with the Young equation for the contact angle (Chapter 4), interfacial theories can be used 

Polytetrafluoroethylene (PTFE, Teflon) 18.5 Poly(ethylene terephthalate) (PET) 43 

Poly(vinylidene fluoride) 25.0 Cellulose - from wood 36-42 

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Fig. X-9. Zisman plots of the contact angles of various homologous series on Teflon O, RX , alkylbenzenes (f), n-alkanes , dialkyl ethers , siloxanes A, miscellaneous polar liquids. (Data from Ref. 78.)...

An important and expensive problem in surface science occurs in the prevention of the attachment of marine animals such as barnacles to ship surfaces, a process known as biofouling. Baier and Meyer [159] have shown that the Zisman plot can be used to predict biofouling, thus avoiding costly field tests to find a successful coating to prevent biofouling. 

What is the critical surface tension for human skin Look up any necessary data and make a Zisman plot of contact angle on skin versus surface tension of water-alcohol mixtures. (Note Ref. 136.)... 

Take the data from Fig. X-12 on the propyl monolayers and make a Zisman plot to determine the critical surface tension for the surface. 

Fig. 10. A schemalic Zisman plot for a given solid specimen. When the cosine of the static advancing contact angle is plotted against the surface tension for a series of apolar liquids against a test solid, a straight line results. Its extrapolation to cost = 1 yields the critical surface tension of the solid.

Critical surface tension data for low-energy surfaces of varying surface chemistry obtained from Zisman plots... 

A requirement underlying the validity of Zisman plots is that there be no specific interactions, such as acid-base interactions, between the solid surface and the probe liquids. Such interactions, however, can, in principle, be taken into account by Young s equation, provided the contact angle remains finite. Their... 

In this experiment Yc will be determined for methylated (hydrophobic) soda glass. Both advancing (0a) and receding (0r) angles will be measured in order to estimate the degree of hysteresis in each case. Use the values of both 0a and 0r, as well as the average, to produce several Zisman plots. 

Contact Angle Goniometry as a Tool for Surface Tension Measurements of Solids, Using Zisman Plot Method 221... 

There is a hysteresis effect associated with the wetting process which arises, at least in part, from the presence of defects and impurities in the surface under study. Thus advancing and retracting contact angles are slightly different. It is conventional to use the advancing contact angle in the Zisman plot. 

FIG. 8.3 (A) Zisman plot for polytetrafluoroethylene using various testing liquids (O) n-alkanes (A)... 

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... 

Zisman Plot See Critical Surface Tension of Wetting. 

Surface tension Interfacial free energy mNm erg cm erg cm Contact angle (microscopy) Zisman plots Contact angle (degradation after prolonged UV irradiation) From isothermal crystallization studies At (2-D to 3-D) interface 16 16.5 16.5-14.4 30 10 (estimate) (53) (53) (54) (39)... 

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... 

Figure 6.18. A Zisman plot for -alkanes on polytetrafluo-roethylene...

Figure 2.10. A Zisman plot for polyethylene the contact angles of a variety of liquids on polyethylene are plotted against the surface tension of each liquid.

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