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In many applications the wettability of a surface or ability of liquids to wet surfaces can be a key factor in a product’s performance or be a significant issue in a manufacturing process. Measurement of wettability is primarily achieived by measuring the contact angle of a liquid on a surface.

At LPD Lab Services Ltd wettability measurements can be performed via contact angle measurements using the Optical Contact Angle (OCA35) and Dynamic Contact Angle Tensiometer (DCAT11)  instruments supplied by Gerhardt UK and manufactured by Data Physics. These assessments are quantitative and can be tied into changes to surface chemistry.

In addition by combining the contact angle measurements with other surface analysis techniques  available at LPD Lab Services such as  XPS, SIMS and AES,  a deeper understanding of the surface chemisrty can be obtained.

The physical behaviour can also be examined by using scanning electron microscopy (SEM) of fibre surface roughness as this affects microscopic wetting and localised contact angles.

The combination of contact angle measurements, surface texture / roughness and surface chemical analysis is a powerful tool to unambiguously assess manufacturing processes, product performance or the reliability of in-line processes such as coating systems.

		Optical Contact Angle Measurement Measurement of static and dynamic contact angles on plane, convex, and concave surfaces, contact angle hysteresis, surface free energy of solids, surface and interfacial tensions and absorption properties.

		Dynamic Contact Angle Tensiometer Measurement of static surface and interfacial tensions on liquids, contact angles on powders, fibre bundles and the adsorption behaviour of liquids on wettable materials.  Measurement of dynamic advancing and receding contact angles, determination of critical micelle formation concentrations of surfactant solutions, surface free energies of solid materials, work of adhesion between liquids and solids.

Example typical applications where wetting and contact angle measurements are important include the following materials and chemicals:

• Paints and Coatings 
• Printing Inks
• Securities Products and Holographic Systems
• Petrochemicals
• Paper and Paper Coatings 
• Polymers
• Adhesives
• Powders
• Surfactants
• Fibres
• Contact lenses
• Medical Devices
• Ceramics
• Cosmetics and Healthcare 
• Microelectronics Wafer Surface Cleanliness
• Agrochemicals.

Data Physics Application Notes for DCAT and OCA

• Surface chemistry characterisation of an important solvent (DPM) for the paint and ink industry by the OCA pendant drop method.
• Absorption of liquids into solid porous media - Quantitative determination of the absorption behaviour of filter membranes using OCA.
• Determining the Surface Tension between coloured printing inks and fountain water solutions by OCA.
• Optimisation of the surface properties (Surface Free Energy) of polymer films using the OCA pendant drop method.
• The OCA lamella method for the determination of surface tension in thick viscous liquids using an electrically heated temperature control system - Surface tensions of molten polymers and hotmelts.
• Simplified OCA determination of wetting properties - Surface free energy of polymer films with just one test liquid.
• Determination of the maximum Work of Adhesion of certain liquids like glues, inks and varnishes using OCA contact angle and IFT data.
• Measurement of the dynamic contact angle on single fibres using DCAT.
• Determination of Wetting Properties (Surface Free Energy) of powders with DCAT.
• Determination of Critical Micelle Concentration for a detergent with DCAT.

Document Title	View
Determination of Surface Tension and Wettability of Liquid on Solid Surfaces