Contact angles apparatuses, types

Section 4.1 briefly describes some of the commonly employed experimental tools and procedures. Chaudhury et al., Israelachvili et al. and Tirrell et al. employed contact mechanics based approach to estimate surface energies of different self-assembled monolayers and polymers. In these studies, the results of these measurements were compared to the results of contact angle measurements. These measurements are reviewed in Section 4.2. The JKR type measurements are discussed in Section 4.2.1, and the measurements done using the surface forces apparatus (SFA) are reviewed in Section 4.2.2. 

The Laboratory Abrasion Tester 100 (LAT 100)65 uses a wheel test piece on an abrasive disk geometry so is the type (d) of Figure 11.4. The abrasive disk is driven and the speed, contact force and the slip angle of the test piece can all be varied. What makes this apparatus so different from all the others is not only the versatility but the sophistication of the instrumentation and the computer control. This means that it can be used to obtain data as a function of several parameters and combine results to make predictions of wear for the extremely complicated service conditions of tyres. Not surprisingly, it is very expensive and unlikely to be used on a routine basis outside of tyre companies. Nevertheless, is has now been proposed for standardization in ISO TC 45. 

These systems are usually quite small and are frequently placed in a special hermetically sealed space in which the temperature, humidity, and pressure may be varied. There are two types of apparatus, differing in the manner of detaching the particles. In systems of the first type [48, 79, 81, 82] a vertical plate (or sphere) is brought up to a freely hanging sphere or the fused end of a filament imtil contact occurs (Fig. 11.13). Then the plate is moved in a direction perpendicular to the area of contact. The deviation (angle a) of the suspended sphere from the vertical due to the action of the adhesive forces serves as a measure of the adhesion ... 

A special ATR apparatus for detecting organic species contaminating a silicon wafer and SiH on the wafer surface has also been developed. As a silicon wafer has a high refractive index (about 3.4), it is necessary to use Ge as the IRE at an angle of incidence >59. To perform the most sensitive measurements, an IRE of the multiple-reflection type is used. Close contact between the IRE and the wafer is necessary, and consequently, a special pressurizing mechanism that ensures total and uniform contact has been developed for this purpose. 

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