Inorganic whiskers evaluation

There are two different methods of surface modification evaluation of inorganic whiskers the direct method and the indirect method. 

The contact angle (0), another criterion for hydrophilicity and lipophilicity, is employed to evaluate the wettability of liquid to solid. Generally, the solid surface is considered to be wetted by liquid when 0 < 90° the solid surface is not considered to be wetted by liquid when 0 > 90° and the solid surface is wetted completely by liquid when 0 = 0°. As for inorganic whiskers, the bigger the contact angle between distilled water and whiskers, the better is the hydrophobicity of whiskers. 

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