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2267. Strobel, M.A., and C.S. Lyons, “An essay on contact angle measurements,” Plasma Processes and Polymers, 8, 8-13, (Jan 2011).

Contact angles are used to solve research and manufacturing problems in an industrial environment. Contact angle measurements are scientific, readily acquired using relatively low-cost instruments and simple procedures, are agreeable for use in environments from academic research laboratories to industrial manufacturing facilities, and are an extremely powerful method for characterizing surfaces. The measurement of dynamic contact angles is rate-dependent at high capillary numbers. Water is a preferred probe liquid for contact angle measurements not only because of the importance of aqueous systems in science and industry, but also because water has the highest surface tension of any commonly available probe liquid and therefore has measurable contact angles on most polymeric materials. Most theories of solid surface energy have a basis in Young's equation, which employs the equilibrium contact angle. If surface energy or surface energy component calculations are made, both the advancing and the receding contact angle data should be used in those calculations.

2403. Strobel,. M.A., M.C. Branch, R.S. Kapaun, and C.S Lyons, “Flame-treating process,” U.S. Patent 5891967, Apr 1999.

The present invention provides a method of modifying the surface of a polymeric substrate, e.g., to improve the wettability of the polymer film surface and/or alter the reactivity of the surface of the substrate by further oxidation, comprising exposing the substrate to a flame. The flame is supported by a fuel and oxidizer mixture that includes an effective amount, for modifying the polymeric substrate, of at least one oxygen-containing compound that functions as a fuel substitute. Oxygen comprises between about 10 and 50 atomic percent of the compound. Large increases in the ASTM wetting test over that reported with conventional flame-treating processes, have been observed in films treated according to this invention. In addition, significant increases in polymer film surface oxidation levels have been observed.

1886. Strohmeier, B.R., “Improving the wettability of aluminum foil with oxygen plasma treatments,” J. Adhesion Science and Technology, 6, 703-718, (1992) (also in Contact Angle, Wettability and Adhesion: Festschrift in Honor of Professor Robert J. Good, K.L. Mittal, ed., p. 453-468, VSP, Nov 1993).

The wettability of aluminum foil is an important concern in many industrial converting processes. X-ray photoelectron spectroscopy (XPS or ESCA) and water contact angle results indicated that relatively mild (i.e. 250 W, 15 s) oxygen plasma treatments efficiently removed residual carbon contamination from cold-rolled foil surfaces. This resulted in a significant improvement in the foil wettability. It was also found that the wettability of plasma-treated foils degraded with time, apparently due to the adsorption of hydrophobic, airborne carbon species and other contaminants. Furthermore, oxygen plasma treatments caused additional aluminum oxide to grow on the metal surface. The composition of this additional oxide was found to be similar to that of the native passivation oxide. The thickness of the aluminum oxide layer increased with both the plasma RF power and the plasma exposure time.

1692. Strom, G., “The importance of surface energetics and dynamic wetting in offset printing,” J. Pulp and Paper Science, 19, J79, (1993).

The surface energetic properties of different areas of the offset printing plate are the key factors of this printing process, since they control the ink transfer during printing. The importance of these factors is discussed for both waterless offset and conventional offset. The printing process is highly dynamic. New surfaces are created and their lifetimes are short. From recent theories of dynamic wetting, it has been concluded that spontaneous removal of ink films from nonimage areas is a very slow due to the high ink viscosity and the low dynamic contact angle. Thus it is of less importance.

358. Su, C.C., “Low volatile organic compounds coatings; surface energy considerations,” in 1993 Polymers, Laminations and Coatings Conference Proceedings, 491-499, TAPPI Press, Aug 1993.

2967. Su, C.H., T.H. Chen, S.H. Yang, C.H. Liu, S. Lin, J.T. Teng, and H. Chen, “Surface properties of polypropylene treated using atmospheric pressure plasma jet,” in Proceedings of the 35th International MATADOR Conference, S. Hinduja and K.-C. Fan, eds., 29-32, Springer, 2007.

Polypropylene (PP) films have been widely used in many industrial areas, such as for protective overcoats and food packaging. However, PP film’s hydrophobic surface properties induce poor wettability and adhesion; these properties have restrained the application of these films. Many surface modification techniques like wet-chemical treatment, UV irradiation, and plasma (including the atmospheric-pressure plasma, APP) treatment have been applied to films to enhance their hydrophilic properties. Among these technologies, APP treatment has attracted much attention due to its dry process, low vacuum equipment cost, and high productivity. In this study, the influence of process parameters would be the reactive gas ratio of plasma. To enhance its surface characteristics, treatment of PP film’s surface by APP was investigated. The XPS, OES, contact angle analyzer, SEM and AFM were used to examine the effect of process variables on film surface characteristics. It was found that Ar plasma mixing with oxygen has a better lasting aging effect. Moreover, the roughness of films is slightly changed after treatment. Through XPS analysis, we observed that the O/C ratio of PP decreases with an increased exposure time in air. Finally, the relationship among the aging time, surface energy, and roughness of the film was also investigated.

1126. Suchaneck, G., M. Guenther, G. Gerlach, K. Sahre, K.-J. Eichhorn, B.Wolf, “Ion-induced chemical and structural modification of polymer surfaces,” in Plasma Processes and Polymers, d'Agostino, R., P. Favia, C. Oehr, and M.R. Wertheimer, eds., 205-222, Wiley-VCH, 2005.

Thin polymer films were irradiated with boron ions with energies from 50 to 180 keV and irradiation doses between 1013 and 1016 B+/cm2. For comparison, plasma modification was performed in NH3 and N2O low-pressure gas discharges. A complex investigation of chemical changes in the surface regions was carried out using attenuated total reflection (ATR)-FTIR spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Optical properties were probed by spectroscopic ellipsometry. Hardness and elastic modulus profiles have been measured by a depth-sensing low-load indentation technique. Additionally, the surface and bulk conductivities of modified polymer films were determined. It could be shown that the increase of ion fluence leads to a partial destruction of the imide, aromatic and sulfone groups. The effective modification depth estimated from the hardness, Young’s modulus and refractive index depth profiles was 250–300 nm at an ion energy of 50 keV and 400–450 nm at an ion energy of 180 keV. In the case of low-pressure plasma treatment, the chemical modification of the polymer bulk extends only a few monolayers and is determined by the electronicprocess-related linear energy transfer (LET). The destruction of chemical bonds under ion bombardment leads to the formation of new amorphous and graphitelike structures, which increase the modified surface film conductivity, the optical absorption index, the density, and the sensitivity of these polymer films to moisture uptake, and decrease the refractive index anisotropy and the Freundlich’s coefficient of the moisture-uptake behavior.

966. Suezer, S., A. Argun, O. Vatansever, and O. Aral, “XPS and water contact angle measurements on aged and corona treated PP,” J. Applied Polymer Science, 74, 1846-1850, (Nov 1999).

Effects of corona treatment and aging on commercially produced corona discharged polypropylene (PP) films were followed via surface sensitive roughness analysis by atomic force microscopy (AFM), water contact angle (WCA), and X-ray photoelectron spectroscopic (XPS) measurements. Roughness analysis by AFM gave similar results for both untreated and corona-treated samples. The measured water contact angle decreased after corona treatment but increased with aging. XPS findings revealed that corona treatment caused an increase in the O-containing species on the surface of the films, but the measured O/C atomic ratio decreased with aging. The angle dependence of the observed XPS O/C atomic ratio further revealed that surface modifications by the corona treatment were buried into the polymer away from the surface as a function of aging. This is attributed to a surface rearrangement of the macromolecules in agreement with the findings of Garbassi et al. on oxygen–plasma-treated polypropylene. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1846–1850, 1999
https://onlinelibrary.wiley.com/doi/abs/10.1002/%28SICI%291097-4628%2819991114%2974%3A7%3C1846%3A%3AAID-APP29%3E3.0.CO%3B2-B

653. Sugita, K., “Wettability and adhesion of polymer surfaces,” Nippon Gomu Kyokaishi, 60, 246+, (1994) (also in International Polymer Science and Technology, Vol. 14, p. 38-46 (Sep 1994)).

2713. Sugizaki, Y., T. Shiina, Y. Tanaka, and A. Suzuki, “Effects of peel angle on peel force of adhesive tape from soft adherend,” J. Adhesion Science and Technology, 30, 2637-2654, (2016).

In the case of the peeling of adhesive tapes from soft adherends, the contributions of the compressive force at the adhered portion as well as the larger deformation of adherend have essential roles in determining the peeling properties. In this paper, the peel force of an adhesive tape from a soft adherend has been measured to understand the peeling mechanism, which is greatly affected by the peel angle. A commercially available pressure-sensitive adhesive was used as the tape, and a cross-linked polydimethylsiloxane (PDMS) was used as the soft adherend. The purpose of this study is to clarify the effects of the peel angle on the peel behavior of this system at room temperature under different material specifications and different experimental conditions. The factors that affect the peel force of the PDMS adherend included the degree of cross-linking in PDMS, the thickness of PDMS, peel angle, and peel velocity. Two characteristic peel patterns were observed, which depended on the material specifications and different experimental conditions. The peel mechanism was discussed in terms of the deformation of the adherend.

2308. Sullivan, M.W., “Process and apparatus for treating plastics,” U.S. Patent 3308045, Mar 1967.

This invention relates to an improved method for treating the surface of plastic materials to render them capable of adhering to subsequently applied coatings such as printing inks, paints, pigments, adhesives, and various other materials which it may be desired to coat, print or otherwise attach to the treated surfaces.

1022. Sullivan, N., M.C. Branch, M. Ulsh, and M. Strobel, “Flame treatment of polyolefin materials: Characterisation of gas phase phenomena,” in 20th Annual Anniversary Meeting Conference Proceedings, 101-103, Adhesion Society, 1997.

971. Sun, C.Q., D. Zhang, and L.C. Wadsworth, “Corona treatment of polyolefin films - A review,” Advances in Polymer Technology, 18, 171-180, (Apr 1999).

Corona discharge introduces polar groups into the polymeric surfaces and, as a consequence, improves the surface energy, wettability, and adhesion characteristics. The main chemical mechanism of corona treatment is oxidation. This article further discusses some special problems that are related to corona treatment of polyolefin films by reviewing the recent developments in this field, such as effect of corona treatment on adhesion, effect of resin additives on corona treatment, insufficient treatment and over-treatment of corona discharge, aging, and re-treatment. © 1999 John Wiley & Sons, Inc. Adv Polym Techn 18: 171–180, 1999
https://onlinelibrary.wiley.com/doi/abs/10.1002/(SICI)1098-2329(199922)18:2%3C171::AID-ADV6%3E3.0.CO;2-8

359. Sun, Q.C., D. Zhang, and L.C. Wadsworth, “Corona treatment on polyolefin films,” TAPPI J., 81, 177-183, (Aug 1998).

360. Sutherland, I., D.M. Brewis, R.J. Heath, and E. Sheng, “Modification of polypropylene surfaces by flame treatment,” Surface and Interface Analysis, 17, 507-510, (Jun 1991).

The changes induced on the surface of polypropylene homopolymer following flame treatment have been studied. Surface compositions were determined using x-ray photoelectron spectroscopy and compared to surface free energies estimated from contact angle measurements. The effect of air-to-gas ratio, total flow rate, contact time with the flame and the distance between the inner cone tip of the flame and the polymer have been investigated. Mild flame treatments were found to be effective in promoting the adhesion of polyurethane paints to the polypropylene. The adhesion between flame-treated polypropylene and the paint film was assessed using a composite butt test and the measured bond strengths were found to be well in excess of those obtained using solvent wiping or chlorinated polyolefin primers.

1951. Sutherland, I., E. Sheng, D.M. Brewis, and R.J. Heath, “Flame treatment and surface characterisation of rubber-modified polypropylene,” J. Adhesion, 44, 17-27, (Oct 1994).

2013. Sutherland, I., R.P. Popat, D.M. Brewis, and R. Calder, “Corona discharge treatment of polyolefins,” in Adhesion International 1993, Sharpe, L.H., ed., 369-380, Gordon and Breach, 1993 (also in J. Adhesion, V. 46, p. 79-88, Sep 1994).

The effects of corona discharge treatment on polyethylene and polypropylene homopolymers have been studied. X-ray photoelectron spectroscopy was used to determine surface compositions which were related to surface free energy estimates from contact angle measurements. Changes in composition and surface free energy were measured as a function of treatment level. The work of adhesion was seen to increase with oxygen incorporation. The increase was not linear and this is attributed to an increase in the degree of sub-surface to near-surface oxidation at intense treatment levels. Aging of samples followed by XPS and contact angle measurement showed that surface wettability is reduced whereas a slight increase in surface oxygen was found. This phenomenon was attributed to the reorientation/migration of functional groups. Morphological examination by scanning electron microscopy indicated no surface roughening at any power level.

2460. Sutton, S.P., “Capillary devices for determination of surface characteristics can contact angles and methods for using same,” U.S. Patent Application 20040187565, Sep 2004.

Devices are presented which allow determination of unknown surface properties through the creation of a channel capillary, comprised in part of the subject surface or surfaces, and measurement of the capillary pressure created by a test fluid within the resultant channel. In various embodiments of the invention, a channel is created in a reference material which is bonded, through some mechanism, to the test surface in order to create a narrow capillary channel. In other embodiments of the invention, the capillary channel is created with test surfaces on either side of standoff strips which space the surfaces a precise distance from one another. Methods are presented for using these capillaries through immersion, along their length, in a bath of test fluid, such that the resultant fluid level provides a measure of capillary pressure. Being, in part, a consequence of the contact angle between the test fluid and the surface or surfaces under consideration, the capillary pressure is a convenient measure of surface properties inherently related to printability, affinity for adhesives, surface contamination by foreign substances, surface roughness, and the like. Devices are presented which allow measurement of test fluid height within the capillary, both in situations where a static equilibrium is achieved, and in situations where a dynamic contact angle is operative as the fluid rises or falls within the capillary.

361. Suzuki, M., A. Kishida, H. Iwata, and Y. Ikada, “Graft copolymerization of acrylamide onto a polyethylene surface pretreated with a glow discharge,” Macromolecules, 19, 1804-1808, (1986).

2245. Szymczyk, K., “Wettability of polymeric solids by ternary mixtures composed of hydrocarbon and fluorocarbon nonionic surfactants,” J. Colloid and Interface Science, 363, 223-231, (Nov 2011).

Contact angle (θ) measurements on poly(tetrafluoroethylene) (PTFE) and polymethyl methacrylate (PMMA) surface were carried out for the systems containing ternary mixtures of surfactants composed of: p-(1,1,3,3-tetramethylbutyl)phenoxypoly(ethylene glycols), Triton X-100 (TX100), Triton X-165 (TX165) and Triton X-114 (TX114), and fluorocarbon surfactants, Zonyl FSN100 (FSN100) and Zonyl FSO100 (FSO100). The aqueous solutions of ternary surfactant mixtures were prepared by adding TX114, FSN100 or FSO100 to binary mixtures of TX100+TX165, where the synergistic effect in the reduction of the surface tension of water (γ(LV)) was determined. From the obtained contact angle values, the relationships between cosθ, the adhesion tension and surface tension of solutions, cosθ and the reciprocal of the surface tension were determined. On the basis of these relationships, the correlation between the critical surface tension of PTFE and PMMA wetting and the surface tension of these polymers as well as the work of adhesion of aqueous solutions of ternary surfactant mixtures to PTFE and PMMA surface were discussed. The critical surface tension of PTFE and PMMA wetting, γ(C), determined from the contact angle measurements of aqueous solutions of surfactants including FSN100 or FSO100 was also discussed in the light of the surface tension changes of PTFE and PMMA under the influence of film formation by fluorocarbon surfactants on the surface of these polymers. The γ(C) values of the studied polymeric solids were found to be different for the mixtures composed of hydrocarbon surfactants in comparison with those of hydrocarbon and fluorocarbon surfactants. In the solutions containing fluorocarbon surfactants, the γ(C) values were different taking into account the contact angle in the range of FSN100 and FSO100 concentration corresponding to their unsaturated monolayer at water-air interface or to that saturated.

1641. Szymczyk, K., A. Zdziennicka, J. Krawczyk, and B. Janczuk, “Wettability, adhesion, adsorption and interface tension in the polymer/surfactant aqueous solution system I: Critical surface tension of polymer wetting and its surface tension,” Colloids and Surfaces A: Physicochemical and Engineering Aspects, 402, 132-138, (May 2012).

The contact angle of aqueous solutions of Triton X-100, Triton X-114, Triton X-165, sodium dodecylsulfate, sodium hexadecylsulfonate, cetyltrimethylammonium bromide, cetylpyridinium bromide, sodium N-lauryl sarcosinate, dodecyldimethyethylammonium bromide, tetradecyltrimethylammonium bromide and benzyldimethyldodecylammonium bromide on polytetrafluoroethylene, polymethyl methacrylate and nylon 6 was studied. The contact angle values were used in the Young equation for the polymer–solution interface tension calculation and for the determination of the critical surface tension of polymer wetting. The critical surface tension of polymer wetting was obtained on the basis of the relationship between the cosine of contact angle and/or the adhesion tension as a function of the surface tension of aqueous solution of studied surfactants and then was discussed in relation to the Lifshitz–van der Waals components and electron-acceptor and electron-donor parameters of polytetrafluoroethylene, polymethyl methacrylate and nylon 6 surface tension. The role of the parameter of interfacial interactions in the relationship between the critical surface tension of polymer wetting and the surface tension was also considered. This parameter was calculated by using the polymer–solution interface tension as well as the polymer and aqueous solutions of surfactant surface tension.

1759. Szymczyk, K., and B. Janczuk, “Wetting behavior of aqueous solutions of binary surfactant mixtures to poly(tetrafluoroethylene),” J. Adhesion Science and Technology, 22, 1145-1157, (2008).

Measurements of the surface tension (γLV) 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.

2258. Szymczyk, K., and B. Janczuk, “Wettability of polymeric solids by aqueous solutions of anionic and nonionic surfactant mixtures,” J. Adhesion Science and Technology, 25, 2641-2657, (2011).

Measurements of the surface tension (γLV) and advancing contact angle () on poly(tetrafluoroethylene) (PTFE) and poly(methyl methacrylate) (PMMA) were carried out for aqueous solutions of sodium decyl sulfate (SDS) and p-(1,1,3,3-tetramethylbutyl)phenoxypoly(ethylene glycol) (TX100) and their mixtures. The results obtained indicate that the values of the surface tension and contact angles of solutions of surfactants on PTFE and PMMA surfaces depend on the concentration and composition of the surfactant mixtures. Calculations based on the Lucassen-Reynders equation indicate that for single surfactants and their mixtures at a given concentration in the bulk phase the values of surface excess concentration of surfactants at water–air and PTFE–water interfaces are nearly the same, so the adsorption of the surfactants at water–air and PTFE–water interfaces should also be the same. However, the adsorption of TX100 and its mixtures with SDS at water–air interface is higher than that at PMMA–water interface, which is confirmed by the ratio of absolute values of molecular interaction parameters at these interfaces calculated on the basis of Rosen approach. If we take into account the hydration of the poly(ethylene oxide) chains of TX100 and acid and base parameters of the surface tension of water it appears that the PMMA surface is covered by the 'pure' water molecules from the solution or molecules connected with the chain of nonionic surfactant. On the other hand, the lack of SDS molecules at the PMMA–water interface may result from the formations of its micelles which are connected with the TX100 chain.

2479. Tadmor R., “Line energy and the relation between advancing, receding, and Young contact angles,” Langmuir, 20, 7659-7664, (Jul 2004).

The line energy associated with the triple phase contact line is a function of local surface defects (chemical and topographical); however, it can still be calculated from the advancing and receding contact angles to which those defects give rise. In this study an expression for the line energy associated with the triple phase contact line is developed. The expression relates the line energy to the drop volume, the interfacial energies, and the actual contact angle (be it advancing, receding, or in between). From the expression we can back calculate the equilibrium Young contact angle, θ 0, as a function of the maximal advancing, θ A, and minimal receding, θ R, contact angles. To keep a certain maximal hysteresis between advancing and receding angles, different line energies are required depending on the three interfacial energies and the drop's volume V. We learn from the obtained expressions that the hysteresis is determined by some dimensionless parameter, script K sign, which is some normalized line energy. The value of script K sign required to keep a constant hysteresis (θ A - θ R) rises to infinity as we get closer to θ 0 = 90°.

1831. Tadros, M.E., P. Hu, and A.W. Adamson, “Adsorption and contact angle studies I: Water on smooth carbon, linear polyethylene, and stearic-acid coated copper,” J. Colloid and Interface Science, 49, 184-195, (Nov 1974).

Ellipsometrically determined adsorption isotherms are reported for water on two types of pyrolytic carbon, on polyethylene, and on stearic acid-coated copper, for relative pressures up to close to the saturation pressure, P0, and for various temperatures. Contact angle data for bulk water on the same solids are included; advancing angles of 60°–90° were found. The adsorbed film thickness reaches 40–80 Å in the first two systems, but only a few angstroms in the second two; correspondingly, the surface pressures of P0, π0, are large in the first two cases and small in the second two. Large contact angle thus does not necessarily imply low π0. The data are fitted to a previously published potential-distortion model, which allows adsorption and contact angle behavior to be related.

2249. Tag, C.M., M. Pykonen, J.B. Rosenhelm, and K. Backfolk, “Wettability of model fountain solutions: The influence on topo-chemical and -physical properties of offset paper,” J. Colloid and Interface Science, 330, 428-436, (Feb 2009).

The surface chemical and physical character of offset paper was studied before and after application of model fountain solutions based on isopropyl alcohol and an alcohol-free surfactant solution. The paper surface features were characterised with atomic force microscopy and the surface energies were determined by contact angle measurements. Changes in the surface chemical properties induced by the fountain solutions were investigated with X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectroscopy. Coated papers wetted with the surfactant solution revealed a slight increase in the root mean square roughness, but the isopropyl alcohol solution led to no observable changes. The change in sub-micro roughness is ascribed not only to substrate swelling or migration of coating constituents but also to the presence of surfactant on the surface. A change in the surface energy and particularly the polar contribution was observed after application of the surfactant solution. The X-ray photoelectron spectroscopy showed an increase in the oxygen-to-carbon ratio, which confirms the presence of surfactant on the surface. Time-of-flight secondary ion mass spectroscopy showed that the isopropyl alcohol solution did not change the elemental composition of the surface whereas the surfactant solution clearly did so. The distribution of surfactant on the surface was confirmed by mapping the characteristic fragments of the molecule.

2366. Tagaki, T., “Corona producing a planographic printing sheet,” U.S. Patent 4036136, Jul 1977.

A method for producing a plate or sheet useful in planographic printing which is characterized in that the surface of an oleophilic body comprising oleophilic resin is subjected to a corona discharge treatment to form a hydrophilic layer on said surface, and that said method can be carried out without difficulty at a low cost and the reproducibility of the printing plate thereby produced is excellent.

1829. Tagawa, M., K. Gotoh, A. Yasukawa, and M. Ikuta, “Estimation of surface free energies and Hamaker constants for fibrous solids by wetting force measurements,” Colloid and Polymer Science, 268, 589-594, (Jun 1990).

Wetting force at three-phase line was measured by the Wilhelmy technique using fibrous solids/liquid/liquid systems. Advancing and receding contact angles were calculated from the wetting forces during fiber immersion and emersion. The obtained results showed that contact angle hysteresis was due to the heterogeneity of the fiber surfaces. The dispersive and polar components of surface free energies of the fibers were determined from the advancing and receding contact angles, respectively. The Hamaker constants of the fibers were estimated from the dispersive components of their surface free energies.

1830. Tagawa, M., N. Ohmae, M. Umeno, K. Gotoh, and A. Yasukawa, “Contact angle hysteresis in carbon fibers studied by wetting force measurements,” Colloid and Polymer Science, 267, 702-706, (Aug 1989).

The surface free energy of polyacrylonitrile carbon fibers was investigated by using the Wilhelmy technique. The difference in surface free energy between immersion and emersion was observed for the carbon fiber pyrolyzed at 2500 °C.

In contrast, the hysteresis disappeared with repyrolyzation of the carbon fibers at 3000 °C. Auger electron spectroscopic analysis indicated that the surface of the latter carbon fiber (repyrolyzed at 3000 °C) consisted of the basal planes of graphite. Rough surface topography of the carbon fiber repyrolyzed at 3000 °C, as observed by scanning electron microscope, did not affect the hysteresis. Therefore, the contact angle hysteresis was attributed to the chemical adsorbants on the activation sites of the fiber surfaces, as detected by Auger electron spectroscopy.

1581. Tahara, M., N.K. Cuong, and Y. Nakashima, “Improvement in adhesion of polyethylene by glow-discharge plasma,” Surface and Coatings Technology, 174, 826-830, (Sep 2003).

The means by which plasma treatment enhances the adhesion of polymer materials, remains obscure. Thus far, two possible mechanisms have been proposed: an increase in surface energy, and the anchor effects imparted by plasma etching. Independently from these mechanisms, reactions between free radicals, generated by plasma irradiation and adhesives are also likely to affect the adhesive properties of polymer materials. Free radicals generated on polyethylene (PE) by glow-discharge plasma were exposed to air and converted to peroxide. The peroxides were converted back to free radicals with the application of heat, and then graft polymerization was initiated, by adding a hydrophilic monomer such as acrylic acid. The peroxides formed by the reaction between free radicals and the oxygen in air was detected by chemiluminescence (CL). In this work, plasma-treated PE surfaces were bonded to aluminum boards, using epoxy resin as an intermediate adhesive and then subjected to a series of peeling tests. The sample with the highest peeling strength also had the highest level of CL-detected peroxides. These findings suggest that the free radicals generated by plasma treatment influence the adhesive properties of the polymer materials.

1256. Tajima, S., and K. Komvopoulos, “Surface modification of low-density polyethylene by inductively coupled argon plasma,” J. Physical Chemistry B, 109, 17623-17629, (Aug 2005).

The surface chemistry and nanotopography of low-density polyethylene (LDPE) were modified by downstream, inductively coupled, radio frequency (rf) Ar plasma without inducing surface damage. The extent of surface modification was controlled by the applied ion energy fluence, determined from the plasma ion density measured with a Langmuir probe. The treated LDPE surfaces were characterized by atomic force microscope (AFM) imaging, contact angle measurements, and X-ray photoelectron spectroscopy (XPS). Analysis of AFM surface images confirmed that topography changes occurred at the nanoscale and that surface damage was insignificant. Contact angle measurements demonstrated an enhancement of the surface hydrophilicity with the increase of the plasma power. XPS results showed surface chemistry changes involving the development of different carbon-oxygen functionalities that increased the surface hydrophilicity. Physical and chemical surface modification was achieved under conditions conducive to high-density inductively coupled rf plasma.

1257. Takahashi, N., A. Goldman, M. Goldman, and J. Rault, “Surface modification of LDPE by a DC corona discharge generated in a point-to-grid system: The influence of geometric parameters of the system on modification power,” J. Electrostatics, 50, 49-63, (Sep 2000).

We examined the influence of the geometric parameters of the system on the modification power as determined by the contact angle on the surface of the treated low-density polyethylene (LDPE). We have found that (1) with a constant electric energy to generate a corona discharge, the modification power decreases as the distance from the center of surface (the point on the film immediately below the point electrode) increases and that the corona discharge in a point-to-grid system can modify the film surface over a wider area than in a point-to-LDPE system without grid; (2) with a constant discharge current, the modification power on the center of surface decreases when the point-to-grid gap in negative corona treatment increases, but increases in positive corona treatment; (3) the modification power compared to the electric energy used to generate a corona discharge (the yield) is inversely proportional to the point-to-grid gap. However, in a positive corona discharge, the yield did not reach zero when the point-to-grid gap was extrapolated to infinity, possibly because the streamer reduces the effective point-to-grid gap and produces neutral activated species along the streamer; and (4) in a negative corona, the modification power as measured by the temperature increases at the plain electrode (anode) and varies with the energy dissipated by neutral activated species.

755. Takata, T. and M. Furukawa, “Surface modification of aramid fibers by a low temperature plasma to improve their adhesion,” in Metallized Plastics: Fundamentals and Applications, K.L. Mittal, ed., 251-268, Marcel Dekker, Nov 1997.

1828. Tamai, Y., T. Matsunaga, and K. Horiuchi, “Surface energy analysis of several organic polymers: Comparision of the two-liquid-contact-angle method with the one-liquid-contact-angle method,” J. Colloid and Interface Science, 60, 112-116, (Jun 1977).

The dispersion force component of surface tension γSd and the nondispersive interaction energy at the water/solid interface (or the nondispersive work of adhesion) ISWn were evaluated for poly-(tetrafluoroethylene) (PTFE), poly(vinylchloride) (PVC) and poly(methylmethacrylate) (PMMA) by the analysis of the contact angles of water drops in hydrocarbon (the two-liquid-contact-angle method). The results were compared with those obtained by the one-liquid-contact-angle method with α-bromonaphthalene and methylene iodide as probe liquids, which is the method usually adopted. The values of γSd from the two-liquid method were considerably larger than those from the one-liquid method, whereas their high sensitivity to error in the measurement of contact angles was taken into account. This discrepancy may be attributed to the neglect of the surface pressure π in the one-liquid method and the π values of the liquids used on the sample solids were calculated.

1102. Tamm, R.R., “Effect of film additives on printing,” in 1998 Polymers, Laminations and Coatings Conference Proceedings, 1067-1071, TAPPI Press, Sep 1998.

1432. Tanaka, K., and M. Kogoma, “Investigation of a new reactant for fluorinated polymer surface treatments with atmospheric pressure glow plasma to improve the adhesive strength,” Intl. J. Adhesion and Adhesives, 23, 515-519, (2003).

Poly(tetrafluoroethylene-co-perfluoro [alkyl vinyl ether]) (PFA) and polytetrafluoroethylene (PTFE) films were treated by three kinds of atmospheric pressure glow plasmas: an untreated sample was treated by He plasma or trimethoxyborane (TMB)/H2/He plasma, and a TMB-absorbed sample was treated by H2/He plasma. TMB was a new reactant for the treatment, to increase the films’ adhesive strength with an epoxy glue. These films were also treated by a wet method using a sodium solution (Tetra-Etch compound) and such films were used as the control samples. The peel strength values of the controls of PFA and PTFE were 3.5 and 9.5 N cm−1, respectively. The adhesive strengths of all plasma-treated PFAs were stronger than those of untreated one. Especially, the peel strength of the TMB/H2/He plasma-treated PFA showed the maximum value of 4.5 N cm−1, which was bigger than that of the control one. The adhesive strength of the TMB/H2/He plasma-treated PTFE films also showed the maximum peel strength, 7.9 N cm−1, but this value did not exceed that of the control PTFE. Such results suggested that the TMB/H2/He plasma had the advantage of providing better adhesive improvement of those polymers, especially PFA than the wet method could provide. The results of XPS and SEM indicated that TMB actively removed fluorine atoms from the polymer surface. Therefore, boron compounds are effective for the improvement of the adhesive strength between the fluorinated polymer and the epoxy glue.

2293. Tanaka, T., K. Vutova, E. Koleva, G. Mladenov, and T. Takagi, “Surface modification of plastic films by charged particles,” in Polymer Surface Modification: Relevance to Adhesion, Vol. 5, K.L. Mittal, ed., CRC Press, 2009.

The surface of polymer materials has been successfully modified by ion implantation. The plasma-source ion implantation (PSII) technique was applied as a surface modification method for poly (ethylene terephthalate)(PET) films. A mass-separated ion accelerator was used for low energy implantation in poly (vinyl chloride)(PVC) and polyamide (PA). The surface electrical conductivity of these polymers was measured. Using our computer program TRIM-MV for simulation of the accelerated ion transport through the polymers, the penetration depths of bombarding ions in the studied plastic films were calculated. The experimentally observed changes in physical properties cannot be explained by the calculated ion ranges and implanted particle energy distributions. For the experimental conditions used, the chemical structure modification of the polymer surface, polymer material erosion, and gas creation and its diffusion through the surface layer are more important reasons for the modified material characteristics. The kind of bombarding ions and the composition of polymer material are found to be of prime importance.

1090. Tanaka, T., M. Yoshida, M. Shinohara, S. Watanabe, and T. Takagi, “Surface modification of PET films by plasma source ion implantation,” in Polymer Surface Modification: Relevance to Adhesion, Vol. 3, K.L. Mittal, ed., 69-82, VSP, Sep 2004.

Abstract Application of a pulsed high negative voltage (approx. 10 us pulse width, 300-900 pulses per second (pps)) to a substrate is found to induce discharge and thereby increase the ion current of an inductively coupled plasma. This plasma source ion implantation (PSII) technique is investigated as a surface modification method for poly (ethylene terephthalate)(PET) films using Ar, N2 and CZHZ gases. PSII treatment of PET with N2 and Ar gases is found to change the color of the PET film, effectively increasing the near-ultraviolet absorption. The effects of the treatment using N2 and Ar gases on the chemical bonding of C, H and O are examined by X-ray photoelectron spectroscopy (XPS). PSII treatment with CZHQ gas is shown to produce a thin diamond-like carbon film on the PET surface. The layer is shown to be smooth by scanning electron microscopy, and the structure is analyzed by XPS and laser Raman spectroscopy. The treatment using CZHZ gas effectively reduces the oxygen transmission rate by up to 100 times that of unmodified PET film at a carbon film thickness of only 70-300 mm.

797. Tatoulian, M., F. Cavalli, G. Lorang, J. Amouroux, and F. Arefi-Khonsari, “Copper metallization of plasma-treated fluorinated polymers: study of the interface and adhesion measurements,” in Polymer Surface Modification: Relevance to Adhesion, Vol. 2, K.L. Mittal, ed., 183-198, VSP, Dec 2000.

Poly(vinylidene fluoride) (PVDF) samples were treated in plasma atmospheres of ammonia, pure N2 and N2/H2 mixtures in order to enhance their adhesion to evaporated copper. The chemical and physical modifications occurring on the plasma treated PVDF films were studied by XPS measurements. The main effects resulting from these treatments were a substantial defluorination and the grafting of oxygen- and nitrogen-containing groups. The adhesion of 20 nm thick copper layers was evaluated by peel test measurements. XPS depth profiles of the samples with Cu overlayers were used to identify chemical bonds at the Cu-PVDF interface.

1074. Tavakoli, S.M., and S.T. Riches, “Laser surface modification of polymers to enhance adhesion, I: Polyolefins,” in Antec '96 Vol. 1, 1219-1224, Society of Plastics Engineers, May 1996.

 

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