Technological applicability, wetting theories

DuPont cites applications in world team tennis T-shirts and athletic socks, golfing apparel and New York Police Department bicycle patrol clothing. The fabrics contain fibers described by DuPont as tetra-channef Dacron . Synthetic fibers are produced with different cross-sectional shapes depending on the extrusion technology (e.g. melt, solvent or wet spun) and the end-use application. The cross-sections of these fibers contain four lobes, thus the description tetra-channef. The theory is that these channels provide for the wicking of perspiration away from the skin surface towards an outer layer of fabric, which in turn absorbs the liquid. DuPont s claims for the performance of CoolMax fabrics are given in Table 10.1. 

Finally, we consider the hydrodynamic theory of thin liquid film rupture. The stability of the liquid films to a great extent is ensured by the property of the adsorbed surfactant to damp the thermally excited fluctuation capillary waves representing peristaltic variations in the film thickness [6]. In addition to the theory of stability of free foam and emulsion films, we consider also the drainage and stability of wetting films, which find application in various coating technologies [7]. 

Equation 4.2 gives the theoretical work of adhesion for ideal interfaces and due only to surface phenomena. Adhesion is a much more complex phenomenon with many applications (e.g. paints, polymer technology and cleaning via surfactant-based formulations). We discuss wetting and adhesion in Chapter 6. Example 4.1 shows how the ideal work of adhesion can be estimated from theories for interfacial tension. 

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