Contact angles Interpretation

Kwok, D.Y., Gietzelt, T., Grundke, K., Jacobasch, H.J., and Neumann, A.W. (1997). Contact angle measurements and contact angle interpretation. 1. Contact angle measurements by axisymmetric drop shape analysis and a goniometer sessile drop technique. Langmuir, 13, 2880-2894. 

D. Li, P. Cheng and A.W. Neumann, Contact Angle Measurement by Axisymmetric Drop Shape Analysis (ADSA), Adv. Colloid Interface Set 39 (1992) 347, and references to the Neumann group in sec. 5.12 D.Y. Kwok, A.W. Neumann, Contact Angle Measurement and Contact Angle Interpretation, Adv. Colloid Interface Set 81 (1999) 167-249. 

Kwok DY, Neumann AW (1999) Contact angle measurement and contact angle interpretation. Adv Colloid Interface Sci 81 167-249... 

Kwok D Y, Neumann AW (20(X)) Contact angle interpretation in terms of solid surface tension. Colloids Surf APhysicochem Eng Asp 161 31-48... 

These comments should not be interpreted to mean that measures of wettability are useless at predicting adhesion. They do seem clearly to indicate that contact angles and critical surface tensions reported for wood are not necessarily thermodynamic quantities or well-defined material parameters. Because most contact angles are dynamic values, they should be interpreted with caution and considered as relative measures of adhesion, for which the absolute scale is yet unknown. Further, we need to keep in mind that although wetting is necessary for adhesion, it may not be the limiting factor in many real situations. 

Silicon has an affinity both for B (at 1500°C Si dissolves up to 17 at.% B (Massalski 1990)) and N (although Si3N4 is less stable than BN). Naidich (1981) achieved stationary contact angles of 95° and 110° for Si on cubic and hexagonal BN at 1500°C in a high vacuum in a few minutes. These values are much higher than those observed for Al, but significantly lower than the 140° or so observed for non-reactive metals. A detailed interpretation of these values is not possible in the absence of information on interfacial reactions which could occur in the Si/BN system. 

Marmur A. (2006) Soft contact measurement and interpretation of contact angles. Soft Matter 2 12-17. 

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