Rolling and Sticking Drops

Rainwater on the windscreen, self-cleaning outside walls by drops rolling off, pesticide drops sticking to leaf surfaces, liquid contact with superhydrophobic surfaces or floor coverings – for many processes the following question is important: Does a drop stick to the surface or does it roll off?

With the aid of the tilting table PA4240 / PA3240 from Krüss for the contact angle measuring systems DSA30 and DSA100 this question can now be answered. The arrangement allows measurement of the roll-off angle for a drop on a surface as well as the dynamic contact angle (advancing and receding angles) of a sliding drop. The latter provide information about the homogeneity and roughness of the solid surface.

The roll-off angle and dynamic contact angle are measured precisely and reproducibly with the high-precision angle drive of 0.1° and a large dynamic table movement range. The software is used to define the starting and finishing points of the tilting movement and coordinate them with the measurement. The drop can be deposited on a level

sample or on a tilted one.

The sample can be tilted until it reaches a vertical position. Rapid assembly means that switching between a tilted measurement and the standard measuring arrangement can be carried out in no time at all. The tilted table can be used with sample sizes up to 75 × 100 × 45mm (L × W × H). For larger samples, or for a combination with

horizontal axes, wafer tables and further accessories, tilting frame PA3220 is used together with the measuring system DSA100.