Surface energetics contact angle

Given the importance of surface and interfacial energies in determining the interfacial adhesion between materials, and the unreliability of the contact angle methods to predict the surface energetics of solids, it has become necessary to develop a new class of theoretical and experimental tools to measure the surface and interfacial energetics of solids. Thia new class of methods is based on the recent developments in the theories of contact mechanics, particularly the JKR theory. 

While direct, this method is the most difficult experimentally due to the diminutive nature of fiber diameters and the uncertainty involved with contact angle measurements and hysteresis. The value i ) can also be measured on flat sheets of the fiber material but due to fabric finishes and different surface properties incurred during manufacture, the surface energetics of the sheet and fiber may be very dissimilar. Therefore, the value of co8i i was determined in the following manner from detergency data. The Kubelka-Munk Equation (12-13),... 

In this section, we have examined the characteristics of fiber surfaces obtained by two-liquid tensiometric technique which could allow the energetic study of cylindrical solids with very small diameter, comparing to the classical contact angle method. 

This chapter discusses the commonly used experimental techniques and practical issues pertaining to the measurement of contact angles, including the preparation of suitable solid surfaces for energetics calculations. 

If surface roughness is the primary cause of hysteresis, it may be impossible to obtain Young contact angles. In such cases, the advancing contact angle is influenced more by the microscopic geometry than it is by interfacial energetics. 

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-... 

Some workers have interpreted the emulsification of fountain solution in an ink from the point of view of surface energetics and colloidal behavior. Surface measurements in the form of contact angles, spreading coefficients, interfacial tensions and surface tensions have been widely used to explain the interactive behavior of inks and fountain solutions. 

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