SPREADING OF LIQUIDS ON SOLIDS UNDER CONTROLLED INTERFACIAL CONDITIONS.
Annual summary rept.,
MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF METALLURGY AND MATERIALS SCIENCE
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The spreading behavior of organic acids, esters, phosphates and alcohols on aluminum, anodized aluminum and Nitralloy in the presence of air has been investigated. The contact angle characterizing the spreading behavior was measured in a captive-bubble apparatus. The effect of the nature of the solid surface on the spreading behavior was evident only in the case of the esters. Hard anodized aluminum immersed in water exhibited a contact angle when an air bubble saturated with pentyl acetate was brought in contact with it. Zero contact angle was observed on aluminum. The implication of the present investigation is that when an autophobic liquid covers a solid in the absence of air, a different molecular configuration is present at the surface from that present when air displaces the liquid. In order for air to displace the liquid, the complex arrangement of the liquid molecules near the surface must be converted or broken down into a monolayer. This process requires an induction period which varies from liquid to liquid and which seems to depend on the degree of saturation of the air by the vapor.
- Atomic and Molecular Physics and Spectroscopy