The objective of this study was to determine the surface free energy components of celнlulose ethers films. The surface free energy parameters were calculated from the contact angles of sessile drops of apolar and polar liquids on cellulose ether films cast on glass slides using the Lifshitz-van der Waals/acid-base (LW/AB) approach according to the method of van Oss, Chaudhury and Good (Chem. Rev. 88, 927-941, 1988). The cellulose ethers studied were hydroxypropyl methylcellulose (HPMC), methylcellulose (MC), hydroxypropylcellulose (HPC) and hydroxyethylcellulose (HEC) and ethylcellulose (EC). The total surface free energy of these cellulose ethers ranged from 29-50 mJ/m2. The overall trend in the values of the thermodynamic terms derived from the surface free energy parameters as indicators of hydrophilicity was in good agreement with the relaнtive bulk solubility and hydration behavior of the polymers. Calculation of the work of adhesion with substrates of varying surface free energy parameters indicated that acid-base interactions made a major contribution to the total work of adhesion between cellulose ethers and bipolar surfaces. Changes in surface free energy as a result of the presence of plasticizer or change in solvent compoнsition for EC films were resolvable with the LW/AB approach. Although no direct correlation could be established between the surface free energy parameters and the type of substitution on the celluнlose backbone for the cellulose ethers, the values of the terms derived from the LW/AB approach were consistent with those of cellulose. The LW/AB approach provides a reasonably consistent method for estimating the surface properties of cellulose ethers and the resulting surface free energy parameters are shown to relate to the interfacial properties of the polymers.

The objective of this study was to determine the surface free energy components of aqueous-based cellulose ether films and compare these values with those of other cellulose polymers. The surface free energy parameters were calculated from the contact angles of sessile drops of apolar and polar liquids on cellulose ether films cast on glass slides using the Lifshitz–van der Waals/acid–base (LW/AB) approach according to the method of van Oss, Chaudhury and Good. The cellulose ethers studied were hydroxypropyl methylcellulose (HPMC), methylcellulose (MC), hydroxypropyl cellulose (HPC) and hydroxyethyl cellulose (HEC). The total surface free energy of these cellulose ethers ranged from 42 to 50 mJ m−². The contribution of the acid–base (AB) component of surface free energy to the total surface free energy of the polymers ranged from 4 to 12%, which was considerably lower than that of cellulose. The cellulose ethers demonstrated near monopolarity and had dominant electron donor (Lewis-base) character. The overall trend in the values of the thermodynamic terms derived from the surface free energy parameters as indicators of hydrophilicity and hydration were in good agreement with the relative bulk solubility and hydration behavior of the polymers. Independent estimates of the AB character of the polymers from work of adhesion terms calculated from the liquid wetting data agreed with those obtained from the surface free energy parameters. Calculation of the work of adhesion with substrates of varying surface free energy parameters indicated that acid–base interactions made a major contribution to the total work of adhesion between cellulose ethers and bipolar surfaces. Although no direct correlation could be established between the surface free energy parameters and the type of substitution on the cellulose backbone for the cellulose ethers, the values of the terms derived from the LW/AB approach were consistent with those of cellulose and ethylcellulose. The LW/AB approach provides a reasonably consistent method for estimating the surface properties of cellulose ethers and the resulting surface free energy parameters are shown to relate to the interfacial properties of the polymers.

Starting from a comparative assessment of the outstanding works on the ring method (du Noüy) for the determination of the surface tension of liquids and its solutions it is shown that the application of this method to surfactant solutions can lead to substantial errors if one follows conventional conditions. These errors are mainly connected with so far unknown phenomena occurring during the raising of the ring and concerning the influence of the hydrophilic vessel wall above the solution level and the stretching of the solution surface. This is demonstrated quantitatively with surfactant solutions of different kind and concentration. These effects can be explained theoretically very simply by introducing certain assumptions on the behaviour of a surfactant adsorption layer on the inner vessel wall. Conditions leading to the elimination of these errors are given, thus enabling the application of the ring method to the determination of the surface tension of surfactant solutions.

COF groups are formed by electron irradiation of PTFE [poly(tetrafluoroethylene)] powders in air, especially at the surface and in near-surface regions which can be easily hydrolysed to carboxyl groups by air humidity. The application of special additives during irradiation leads to modified micropowders. Fourier transform infrared (FTIR) spectroscopy enables the detection of carboxyl and COF groups. γ-Irradiation of PTFE mainly causes degradation of the polymer; the concentration of carboxyl groups is much lower. Carboxylated micropowders created via radiation treatment retain the essential properties of PTFE. With increasing radiation dose, the increasing concentration of functional groups in the micropowders causes an increase in the surface free energy. This diminishes the strong water and oil repellency of PTFE in such a way that homogeneous incorporation into aqueous and organic liquids or other polymers is possible. So, the special properties of PTFE can be made effective in these media. Modified PTFE micropowders have been successfully tested in many application areas. The aim of our present work was to increase the concentration and vary the nature of functional groups by radiation-chemical methods or chemical conversion of COF groups (polymer-analogous reactions). A highly modified PTFE powder was used to reduce the repellent properties of PTFE diaphragms for application in brine electrolysis. The COF groups of the micropowders were modified by γ-aminopropyltriethoxysilane. The irradiation of FEP [poly(tetrafluoroethylene-co-hexafluoropropylene)] and PFA [poly(tetrafluoroethylene-co-perfluoroalkylvinylether)] yields products which contain a higher content of carboxyl groups than PTFE.

Plasma treatment is one of the methods currently used to obtain polymeric materials with surface properties appropriate to the functionality for which they were designed. However, the effects achieved after surface modification are not always long lasting and involve chemical and physical changes in the outermost layer. In this context, the effects of both argon and oxygen plasma on polylactic acid (PLA) films deposited on titanium were studied to determine which physical and chemical processes occur at the surface, and their duration. Regarding physical surface changes, there were scarcely any differences between both plasmas: roughness was very similar after treatments, root mean square height (Sq) being 10 times higher than the control, without plasma. Water contact angle (WCA) showed that the surface became more hydrophilic after application of the plasma, although hydrophilization was longer lasting in the case of argon treatment.

With regard to chemical changes, it was observed that the argon plasma treatment caused greater fragmentation of the polymer chains, and increased crosslinking between them. ToF-SIMS analysis made it possible to propose mechanisms to explain the formation of the fragments observed.

The carbon fibers (CFs) reinforced polytetrafluoroethylene (PTFE) composites have been modified using proton irradiation, and the surface energy, hardness and tribological properties have been investigated before and after irradiation. The CFs increased the hardness and the wear resistance. Proton irradiation led to defluorination and carbonization of the CF/PTFE composite surface, and decreased the surface wettability and the surface energy. The irradiation depth was 820 nm from the material surface calculated with SRIM software package. In addition, the wear resistance was improved after proton irradiation. Proton irradiation improved the wear resistance of the composite and induced the material transfer from Cu alloy surface to CF/PTFE. These significant improvements could enable potential applications in aeronautics and smart medical materials.

Modification of polyolefin surfaces is often necessary to achieve improved printability, lamination, etc. Although corona discharge and flame treatments can produce the higher surface energy needed for these applications, the properties of the resulting surfaces are not always optimal. Atmospheric pressure plasma is a surface modification technique that is similar to corona discharge treatment, but with more control, greater uniformity, and higher efficiency. Using an atmospheric pressure plasma unit with a dielectric barrier discharge generated using an asymmetric pulse voltage, the effects of different gases, powers, and linespeeds on polyethylene surface treatment were studied. Our results show that atmospheric pressure plasma can be used to achieve higher long-term wettability, higher surface oxygen and nitrogen, and a greater range of surface chemistries with better robustness versus standard corona treatment. Atomic force microscopy results suggest significant differences in the mechanism of surface functionalization versus etching and ablation depending on the gases used. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 319–331, 1999
https://onlinelibrary.wiley.com/doi/abs/10.1002/%28SICI%291097-4628%2819990110%2971%3A2%3C319%3A%3AAID-APP16%3E3.0.CO%3B2-T

Ethylene-propylene diene monomer (EPDM) containing dicyclopentadiene (DCPD) and ethylidene norbornene (ENB) as the termonomers, styrene-butadiene rubber (SBR), and acrylonitrile-butadiene rubber (NBR) have been surface-modified by 10% methyl ethyl ketone (MEK) solutions of trimethylol propane triacrylate (TMPTA) at an irradiation dose of 100 kGy. The irradiation dose and TMPTA concentration were optimized using samples treated with 2, 5, 10, 20, and 50% TMPTA and 50, 100, 200, and 500 kGy doses. Two per cent solutions of acrylate rubber having diene, chloro, and epoxy groups at the reactive sites and tripropyleneglycol diacrylate (TPGDA) and tetramethylol methane tetracrylate (TMMT) were also employed as the surface modifiers. The level and nature of the vulcanization system were varied. The modified rubbers were characterized by attenuated total reflection infrared (ATR-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and contact angle measurements. IR and XPS studies confirmed the generation of polar groups such as CO and COC on the surfaces. The contact angles and the surface energy change with the nature of the modifiers, rubbers, diene monomers, the crosslinking system and the level of the curing agent. The total surface energy and the thermodynamic work of adhesion of the different systems have been correlated with the amount and the nature of the polar groups generated.

This paper, as the title underlines, will be focused on flame treatment technology applications, mainly on BOPP substrates.

After an introduction regarding flame chemistry and BOPP surface activation mechanisms, this paper will be focused on unique flame treatment oxidation performances, in comparison with other treatment methods actually used in the market.

Focus will then be moved to the characteristics and advantages of using flame treatment for film surface treatment. In particular, a comparison will be run with other surface treatment technologies (corona surface treatment and atmospheric plasma treatment) in terms of:

• q surface energy after treatment;
• surface oxidation mechanisms and chemical species involved;
• quantity of oxygen on treated surface (oxidation level);
• quality of oxygen on treated surface;
• adhesion;
• printability/print quality.

Typical and new applications of flame treatment will be presented, underlining benefits coming from flame usage for pretreating different types of skins. Finally, the paper will try to make rid of prejudices and misinformation concerning flame treatment process applications, especially to certain kind of webs and substrates.

The strength of an adhesive bond depends on the thermodynamic work of adhesion, among other properties. In this paper, we report the direct measurement of the thermodynamic work of cohesion and adhesion between poly(ethylene terephthalate) (PET) and polyethylene (PE) films. The pull-off force between polymer surfaces was measured using the surface forces apparatus (SFA). Thermodynamic work of adhesion was determined from pull-off force measurements using the theory of contact mechanics developed by Johnson, Kendall, and Roberts (JKR theory). The values of the surface energies of PET and PE, and the interfacial energy between PET and PE were obtained from these measurements. The dependence of the measured values of the work of adhesion on the rate of separation, time in contact, and other variables that could reflect an irreversible contribution to the measured adhesion was found to be negligible. The critical surface tensions of PET and PE were determined from contact angle measurements. The critical surface tension of wetting depends on the characteristics of the probe liquids. The surface energy of PET determined by the direct force measurements is higher than the critical surface tension of wetting. These values are 61.2 mJ/m² and about 43 mJ/m , respectively. However, in the case of PE the surface energy determined using the SFA and the critical surface tension of wetting are about the same, 33 mJ/m². The interfacial energy between PET and PE, obtained from direct measurements, is about 17.1 mJ/m².

The measurements of the contact angle of the aqueous solutions of TX-100 and TX-165 mixture with propanol on polytetrafluoroethylene (PTFE) and polymethyl methacrylate (PMMA) were carried out. On the basis of the obtained results, the dependence between the cosine of contact angle and surface tension as well as between the adhesion and surface tension of the solutions in the light of the work of adhesion of the solutions to the PTFE and PMMA surface was discussed. The dependence between the adhesion and surface tension for PMMA was correlated to the surface concentration of propanol as well as TX-100 and TX-165 mixture concentration determined from the Frumkin equation at the PMMA-air, PMMA-solution and solution–air interfaces. For this purpose, the surface tension of PMMA covered by a surface active agent film was determined using the Neumann et al. equation and next the PMMA–solution interface tension was evaluated from the Young equation. The values of the surface tension of PMMA covered by propanol and surfactants mixture layer were applied to describe the changes of the adhesion work of solutions to PMMA surface as a function of propanol and surfactants mixture concentration. The adhesion work of the aqueous solutions of TX-100 and TX-165 mixture with propanol to the PTFE and PMMA surfaces was discussed in the light of the adhesion work of particular components of the solutions. On the basis of the results obtained from the contact angle measurements, the standard Gibbs free energy of adsorption of particular components of solution was also considered.