Measurements of the surface tension (γ_LV) and advancing contact angle () on poly(tetrafluoroethylene) (PTFE) were carried out for aqueous solutions of cetyltrimethylammonium bromide (CTAB), cetylpyridynium bromide (CPyB), sodium decylsulfate (SDS), sodium dodecylsulfate (SDDS), p-(1,1,3,3-tetramethylbutyl) phenoxypoly(ethylene glycol)s, Triton X-100 (TX100) and Triton X-165 (TX165) and their mixtures. The results obtained indicate that the values of the surface tension and wettability of PTFE depend on the concentration and composition of the surfactants mixture. In contrast to Zisman finding, there was no linear dependence between cos and the surface tension of aqueous solutions of surfactants and their mixtures for all studied systems, but a linear dependence existed between the adhesional tension and solution surface tension for PTFE in the whole concentration range, the slope of which was –1, indicating that the surface excess concentration of surfactant at the PTFE–solution interface was the same as that at the solution–air interface for a given bulk concentration. It was also found that the work of adhesion of aqueous solutions of surfactants and their mixtures to PTFE surface did not depend on the type of surfactant, its concentration and composition of the mixture. This means that for the studied systems the interaction across PTFE–solution interface was constant, and it was largely of Lifshitz–van der Waals type. On the basis of the surface tension of PTFE and the Young equation and thermodynamic analysis of the work of adhesion of aqueous solutions of surfactants to the polymer surface it was found that in the case of PTFE the changes of the contact angle as a function of the total mixture concentration in the bulk phase resulted only from changes of the polar component of the solution surface tension.

In this paper, we present a simple, yet novel, method, utilizing scraping to obtain continuous rough microstructures over large areas, leading to a tunable wettability conversion from hydrophilicity to superhydrophobicity on polymer surfaces. A series of polymers ranging from hydrophobic to hydrophilic were used, and we found that the wettability of these polymer surfaces could be modified by the scraping process, irrespective of their hydrophobicity or hydrophilicity. More importantly, those polymers with contact angle ranging from 65° to 90° on their smooth surfaces also exhibit enhanced hydrophobicity after scraping. Our results indicate that 65° is the critical value which is more suitable to define hydrophobicity and hydrophilicity for polymer materials.

Cleanliness can be characterized in industrial applications via "simple" wettability measurements, and has been successfully done so for at least two centuries. A problem in much of general manufacturing and maintenance industries is not that more sophisticated measurement and evaluation technology is necessary to provide value, but that technology developed at least several generations ago has not been more widely and profitably used. This paper describes and references that technology, and identifies published case histories where it has been both successfully and unsuccessfully used.

Surface modification of polyethylene (PE), poly(vinylchloride) (PVC), and polystyrene (PS), was performed by thermal-ozone (O₃) treatment to improve their properties. Polymer films were exposed to dried O₃ gas with 3026 ppm at different temperatures. DRS-FT-IR and UV-Vis-NIR absorption methods were applied to observe the surface characteristics of polymers treated. Absorption band assigned to CO stretching appeared near 1720 cm^-1 in films treated with O₃ at 65°C, whereas O₃ treatment at 25°C showed no appearance of the CO band on the surface. In PS, the O3 oxidation proceeded regardless of temperature. Comparison between PE-O₃ and PS-O₃ systems showed that different processes of the surface modification occured. Furthermore, contact angle measurements indicated that the surface wettability of PE and PS was improved by the thermal-O₃ treatment.

In the broad spectrum of contamination control, a major concern is the presence of organic contamination on various inorganic surfaces. In order to control surface contamination of materials, a rapid-detection method is required that does not adversely affect the surface. Wettability measurements provide a convenient and rapid method for probing the outermost surface of a material. The technique is highly surface specific, generally exceeding the sensitivity of electron spectroscopies and is sensitive to a fraction of a monolayer. The most widely used quantitative measure of wettability is the contact angle. When a drop of a liquid with a sufficiently small size is placed on a smooth, flat, homogeneous solid substrate, the drop takes the shape of a spherical cap. The shape of the drop approximates that of a spherical cap when the forces other than the surface tension become negligible. Each solid and liquid (and vapor phase) combination gives rise to a specific degree of wettability. The parameter defining the wettability is the observed contact-angle; the lower the contact angle, the higher the wettability. This angle is measured between a tangent to the liquid surface where it meets the solid substrate and the plane of the solid substrate. It is found that any test of surface cleanliness involving wettability by water cannot be used on metal surfaces that have an indeterminate oxide layer. It is tempting to assume that any clean metal oxide surface would be hydrophilic, but even this rule may have some exceptions.

Non-thermal atmospheric pressure plasma jets/plumes are playing an increasingly important role in various plasma processing applications. This is because of their practical capability to provide plasmas that are not spatially bound or confined by electrodes. This capability is very desirable in many situations such as in biomedical applications. Various types of ‘cold’ plasma jets have, therefore, been developed to better suit specific uses. In this paper a review of the different cold plasma jets developed to date is presented. The jets are classified according to their power sources, which cover a wide frequency spectrum from DC to microwaves. Each jet is characterized by providing its operational parameters such as its electrodes system, plasma temperature, jet/plume geometrical size (length, radius), power consumption, and gas mixtures used. Applications of each jet are also briefly covered.

In the article the analysis of the main methods of calculations of interfacial free energy and surface free energy (SEP) values of solids, in which contact angle measurements' results play a key role, has been presented. The importance of Young's equation and Berthelot's hypothesis as the scientific basis of these methods has been indicated. Various methods of calculations of interfacial free energy values for solid-liquid systems, including calculations of this energy on the basis of state equations or SEP divide to independent components, (especially for polymers) were discussed. The most important methods of calculations of SEP values for polymeric materials on this basis were characterized. The methods of calculations of contact angle values for porous materials, granulated products, powders or fibers on the basis of Washburn equation, what is a base for calculations of SEP of these materials, were presented.

Extrusion coating, lamination and film lamination give rise to complex manufacturing techniques which allow a converter to make high-performance packaging films. The physical properties and the related performance characteristics of composites obtained by extrusion coating and lamination can be comparable to that produced by film lamination. This is not surprising since many of the major components involved by these techniques in the production of the final composites are also the same. The paper examines how the use of ozone combined with corona discharge compares to ozone combined with atmospheric plasma relative to seal strength for these composite film constructions, and suggests a direction for future improvements in seal strength.

The molecular parameters of poly(vinyl alcohol) have enormous effects on its physical and chemical properties. Therefore, the surface characteristics of poly(vinyl alcohol) films are also determined by the molecular parameters. In this study, the dependence of the surface free energy on the molecular weight, degree of saponification, and stereoregularity of poly(vinyl alcohol) films has been evaluated with contact-angle measurements. The surface free energy of poly(vinyl alcohol) films increases with decreases in the syndiotactic dyad content, molecular weight, and degree of saponification. The polar component of the surface energy is not affected by the deviation of the molecular weight and degree of saponification very much. However, it decreases with increases in the syndiotactic dyad content and ranges from 11.64 to 4.35 dyn/cm.
© 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 https://onlinelibrary.wiley.com/doi/abs/10.1002/app.26010

Atmospheric pressure plasma treatment has unique advantages over vacuum treatment for such industrial applications as surface energy ehancement of materials, cleaning, decontamination, and sterilization of surfaces, surface etching, plasma chemical vapor deposition (PCVD), and related tasks. The MOD VIII plasma reactor system has been developed to provide roll-to-roll surface treatment of fabrics and films using a One Atmosphere Uniform Glow Discharge Plasma (OAUGDP®) operating in air. Webs can be continuously and uniformly treated by proper control of gas flow; electrode configuration; plasma voltage, current, and frequency; fabric speed; and fabric tension.

In this paper, polyester (PET) and polypropylene (PP) films are modified by a dielectric barrier discharge in air, helium and argon at medium pressure (5.0 kPa). The plasma-modified surfaces are characterized by contact angle measurements and X-ray photoelectron spectroscopy (XPS) as a function of energy density. The polymer films, modified in air, helium and argon, show a remarkable increase in hydrophilicity due to the implantation of oxygen-containing groups, such as C–O, O–CO and CO. Atomic oxygen, OH radicals, UV photons and ions, present in the discharge, create radicals at the polymer surfaces, which are able to react with oxygen species, resulting in the formation of oxygen-containing functionalities on the polymer surfaces. It is shown that an air plasma is more efficient in implanting oxygen functionalities than an argon plasma, which is more efficient than a helium plasma. In an air plasma, most of the created radicals at the polymer surface will quickly react with an oxygen particle, resulting in an efficient implantation of oxygen functionalities. However, in an argon and helium plasma, the created radicals can react with an oxygen particle, but can also recombine with each other resulting in the formation of an oxidized cross-linked structure. This cross-linking process will inhibit the implantation of oxygen, resulting in a lower efficiency. In argon plasma, more ions are present to create radicals, therefore, more radicals are able to react with oxygen species. This can explain the higher efficiency of an argon plasma compared to a helium plasma.

The most important function of a packaging material is to shield the product inside the package. Extrusion coated paperboard is generally used in food, medical and cosmetic packages. Extrusion coatings give a barrier against water, water vapour, aroma, grease, oxygen, etc. In addition to barrier properties, heat sealability and printability are important properties in packaging applications. From point of view of printing, the dense and impervious structure of extrusion coatings is challenging: printing inks and toners do not penetrate into the coatings. The durability of the printed image is significant, because the image must withstand various converting operations when the package is constructed. The most common method for obtaining good ink adhesion is to oxidize the surface. Surface treatments are used to change the chemical composition, increase the surface energy, modify the crystalline morphology and surface topography, or remove the contaminants and weak boundary layers. Two widely used methods are electrical corona discharge treatment and flame treatment. These processes generally cause physical or chemical changes in a thin surface layer without affecting the bulk properties. Treatments will increase surface energy and also provide polar molecular groups necessary for good bonds between ink and polymer molecules. In addition to printability, surface treatments also affect the heat sealing properties of extrusion coatings. In this study, the surface chemistry of the extrusion coatings has been modified with corona and flame treatments. The effect of corona and flame treatment on surface energy has been evaluated with contact angle measurements. Surface energy has the habit of decreasing with time after treatment. In this work, the decay of surface energy and surface oxidation is followed for six months. ESCA and FTIR-ATR have been used to analyze oxidation and the surface chemical composition. Furthermore, the heat sealing and hot tack properties of the extrusion coatings are evaluated. The aim of this study is also to evaluate printability of extrusion coatings and to map out the role of surface modification in print quality formation. This study has concentrated on digital printing, particularly on dry toner-based electrophotographic printing process.