Search

Surface free energy measurements of solids are a very important issue in various fields of science. Many functional, chemical and physical properties of a given material depend on its surface free energy. The basic method of the surface free energy determination are the contact angle measurements. The aim of this paper was to study the significance of the receding contact angle measurements in the determination of surface free energy of solids. Based on the materials with various surface properties such as glass, mica, silicon wafers and PMMA, the contact angle measurements were proved to be a very important step in the surface free energy calculations. Referring to some commonly used theories, it was proved that considering only the advancing contact angles during the surface free energy calculations leads to its underestimation and incorrect values of its components. Thus, it was found that the receding contact angle is as an important parameter as the advancing contact angle in the surface free energy determination. [ABSTRACT FROM AUTHOR]

The paper presents the studies of metal wettability using two methods: the sessile droplet and immersion ones. Based on the measured contact angles, there was calculated apparent surface free energy from the acidic-basic approach and the contact angle hysteresis. The advancing contact angles measured using the immersion method exhibit a little higher values than those measured by the sessile droplet method. The application of the immersion method leads to obtaining higher contact angle hysteresis. Both methods give different values of contact angles but they can be applied independently for estimation of metal surface wettability. [ABSTRACT FROM AUTHOR]

Wettability of solids is a key phenomenon in many processes. One should mentioned those which accompany us in our everyday life i.e. washing or cementing as well as those applied in industry e.g. flotation of minerals. Value of the contact angles are affected by many factors. One of them is temperature. In this paper monocrystaline quartz was used in the investigations which were carried out in the range 5−50°C with the step every 5°C. As follows the value of the contact angle of both water and diiodomethane changes with the increasing temperature. The change of its value for water is much larger than in case of another liquids of apolar character. Using Chibowski approach the apparent surface free energy was calculated in two ways with and without correction about temperature change of the surface tension. The calculation show difference between both results. Taking into consideration another value of the surface tension should not be neglected even if measurements is taken at a temperature close to 20°C which is the standard in one in such measurements [ABSTRACT FROM AUTHOR]

The article discusses plasma treatment that imparts changes in the properties of the surface and thus, helpful for modifying polymers, namely polypropylene (PP), polyethylene (PE) and polymethylmethacrylate (PMMA). The article also presents an experiment which includes the use of air plasma treatment on PMMA modification. The results of the experiment include an increase in the oxygen atoms, in the polar interactions of the PMMA surface free energy, and in the surface roughness of the PMMA.

The aim of the research was to determine how the drop size affects the contact angle values and determine its optimal size for further contact angle measurements and comparison of the contact angle values measured for three probe liquids (water, formamide, diiodomethane) on the glass surface using the: sessile drop and tilting plate methods. Next, using the measured contact angles, the total surface free energy and its components were determined from the van Oss et al. (Lifshitz-van der Waals acid- base component, LWAB), Owens-Wendt, Neumann and contact angle hysteresis (CAH) approaches. The studies showed, that drop size is very important for contact angle measurements and consequently, for surface free energy estimation. [ABSTRACT FROM AUTHOR]