Low adhesion of hydrophobic powders materials occurs due to high interfacialtension between the powders and the dispersion medium. Because of this tension,the contact angle between the solid and liquid phases remains very high. By usingsurface active agents, the interfacial tension can be lowered to decrease the contactangle, resulting in good wetting. The hydrocarbon chain of the surface active agentsis adsorbed onto the hydrophobic surface of the particles and the polar end remainswith the liquid medium. Thus the interfacial tension can be reduced to get thedesired wetting of the solid materials. Wetting of solids can be determined by usingYoung’s equation (Adamson 1990):
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