Interaction of liquids with solid surfaces is of key importance in many applications such as dissolution of pharmaceutical tablets or digestion of food components. Interaction of the liquid with the solid surface of the specimen - often entitled as wettability - is the first step towards dissolution.
Measurement of the advancing contact angle and/or the drop penetration time helps to get a better understanding of the wettability of the surface by the respective liquid. Whereas the advancing contact angle is mostly dependent on the surface properties of the solid material, the drop penetration time also includes other physical parameters as particle morphology and porosity.
Subsequently, the results of these wettability investigations can be further correlated with the actually-measured porosity and the hydrophilic or hydrofobic character of the materials' surface. To this end, water vapour adsorption isotherms can be measured under controlled conditions of temperature and relative humidity.
Combination of the results of these investigations has proven to be very useful in optimizing materials' performance.