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2082. Le, Q.T., J.J. Pireaux, and J.J. Verbist, “Surface modification of PET films with RF plasma and adhesion of in situ evaporated Al on PET,” Surface and Interface Analysis, 22, 224-229, (Jul 1994).

PET (Polyethylene terephthalate) films were modified with two different plasmas, nitrogen and oxygen, as a function of treatment times and RF powers. Firstly, the chemical composition of the plasma-modified PET films was investigated by XPS. In the case of nitrogen plasma, the formation of amine, imine and amide groups is detected. A slight diffusion of nitrogen-containing species into the PET bulk is also observed by angle-resolved XPS measurements. The appearance of alcohol, carbonyl and carboxyl functions is observed in the case of oxygen plasma treatment. After thermal deposition of an aluminium film, peel tests reveal that the Al/PET adhesion increases as follows: untreated < nitrogen plasma < oxygen plasma treatment.

Secondly, after sevderal successive depositions of thermally evaporated Al on oxygen plasma treated PET film, XPS was used to study the chemistry at the interface. The XPS results reveal that the additional reactive sites created on the PET surface by the treatment explain the significant improvement in Al/PET adhesion observed for plasma-modified samples.

2047. Tsuchida, M., and Z. Osawa, “Effect of ageing atmospheres on the changes in surface free energies of oxygen plasma-treated polyethylene films,” Colloid and Polymer Science, 272, 770-776, (Jul 1994).

The changes in the surface properties of oxygen plasma-treated polyethylene films during ageing in various atmospheres (water, dry nitrogen gas, and hexane) were studied from the viewpoint of the interaction of the surface functional groups formed on the films and the ageing media. The XPS (x-ray photoelectron spectroscopy) and the SSIMS (static secondary ion mass spectrometry) spectra indicated the formation of polar groups containing oxygen such as C=O on the film surface. The changes in the critical surface tension (γC) of the film with ageing time were largely affected by the ageing atmospheres: the γC value of the film aged in water increased, and those of the films aged in nitrogen gas and hexane decreased with an increase in ageing time. These different tendencies among the ageing media could be understood reasonably with examining the surface free energy ratios (the total energy, γtotS, the dispersion force component, γdStotS, the polar component, γpStotS, the hydrogen bonding component, γhStotS) of the films. The ageing in water of which γL is large gave the films with higher γpStotS values, suggeting that the overturn and/or the orientation of the polar groups toward the water phase occurred so as to minimize the discrepancy of the surface free energy between the polymer surface and water. On the other hand, the ageing in nitrogen gas and hexane media of which γL are small gave the films with lower γpStotS and γhStotS values, suggesting the overturn and/or the orientation of the polar groups into the bulk polymer.

1823. Yasuda, T., T. Okuno, and H. Yasuda, “Contact angle of water on polymer surfaces,” Langmuir, 10, 2435-2439, (Jul 1994).

1266. Belgacem, M.N., P. Bataille, and S. Sapieha, “Effect of corona modification on the mechanical properties of polypropylene/cellulose composites,” J. Applied Polymer Science, 53, 379-385, (Jul 1994).

The effect of various corona treatment conditions on the mechanical properties of cellulose fibers/polypropylene composites was studied. The cellulose fibers and polypropylene were modified using a wide range of corona treatment levels and concentrations of oxygen. The treatment level of the fibers was evaluated using the electrical conductance of their aqueous suspensions. The mechanical properties of composites obtained from different combinations of treated or untreated cellulose fibers and polypropylene were characterized by tensile stress–strain measurements; they improved substantially when either the cellulose fibers alone or both components were treated, although composites made from untreated cellulose fibers and treated polypropylene showed a relatively small improvement. The results obtained indicate that dispersive forces are mostly responsible for the enhanced adhesion. The relationship between the electrical conductance of the fibers, the mechanical properties, and the mechanism of improved adhesion is discussed. © 1994 John Wiley & Sons, Inc.

201. Krueger, J.J., and K.T. Hodgson, “Single-fiber wettability of highly sized pulp fibers,” TAPPI J., 77, 83-88, (Jul 1994).

2035. Masse, P., J.P. Cavrot, P. Francois, J.M. Lefebvre, and B. Escaig, “Adhesion improvement of high modulus polyethylene fibers by surface plasma treatment: Evaluation by pull-out testing,” Polymer Composites, 15, 247-251, (Jun 1994).

1446. Badey, J.P., E. Urbaczewski-Espuche, Y. Jugnet, D. Sage, and T.M. Duc, “Surface modification of polytetrafluoroethylene by microwave downstream treatment,” Polymer, 35, 2472-2479, (Jun 1994).

The surface modification of polytetrafluoroethylene (PTFE) by microwave plasma treatment was investigated by means of contact angle measurement and e.s.c.a. studies. Various gases (e.g. O2, O2N2, NH3) were used. The influence of the various plasma parameters, such as power, gas flow, distance between the sample and the centre of the discharge, treatment time, etc., has been evaluated. No modification was induced by O2 and O2N2 treatment, whatever the treatment conditions. NH3 plasma irradiation, however, rendered the PTFE surfaces more hydrophilic, leading to an increase of the polar component of the surface energy from 4.5 to ∼ 57 mJ m−2 under optimized treatment conditions. NH3 treatment led to defluorination, crosslinking, hydrocarbon (CC,CH) bond formation, and incorporation of nitrogen-containing groups, as confirmed by e.s.c.a. Oxygen was also detected at the surface of treated PTFE. Correlations between the contact angle, defluorination rate, and surface nitrogen and oxygen contents, have been established. Optimization of operational NH3 plasma parameters, leading to the best wettability of the treated samples, is also reported.

950. Podhajny, R.M., “Converters consultant: I know corona treatment of films improves ink adhesion, but what else does it do to my film?,” Converting, 12, 20, (Jun 1994).

2391. Yoshikawa, M., Y. Kusano, S. Akiyama, K. Naito, and S. Okazaki, “Method and apparatus for surface treatment,” U.S. Patent 5316739, May 1994.

752. Kolluri, O.S., “Application of plasma technology for improved adhesion of materials.,” in Handbook of Adhesive Technology, K.L. Mittal and A. Pizzi, eds., 35-46, Marcel Dekker, May 1994 (also in Handbook of Adhesive Technology, 2nd Ed., A. Pizzi and K.L. Mittal, eds., p. 193-204, Marcel Dekker, Aug 2003).

Adhesion, whether the bonding of polymers or the adhesion of coatings to polymer surfaces, is a recurring and difficult problem for all industries that use these materials as key components in their products. Designers must often select specially formulated and expensive polymeric materials to ensure satisfactory adhesion (albeit even these materials often require surface preparation). In some cases, entire design concepts must be abandoned due to the prohibitive cost of the required polymer or the failure of crucial bonds. Historically, surface treatments to improve adhesion of coatings to plastics consisted of mechanical abrasion, solvent wiping, solvent swell that was followed by acid or caustic etching, flame treatment, or corona surface treatment. Each of these treatments has limitations, thus providing a strong driving force for the development of alternative surface preparation methods. Many of the common methods mentioned are accompanied by safety and environmental risks, increased risk of part damage, and expensive pollution and disposal problems.

751. Schultz, J., and M. Nardin, “Theories and mechanisms of adhesion,” in Adhesion Promotion Techniques, K.L. Mittal and A. Pizzi, eds., 19-34, Marcel Dekker, May 1994 (also in Handbook of Adhesive Technology, 2nd Ed., A. Pizzi and K.L. Mittal, eds., p. 53-68, Marcel Dekker, Aug 2003).

Adhesion phenomena are relevant to many scientific and technological areas and in recent years have become a very important field of study. The main application of adhesion is bonding by adhesives, which is replacing, at least partially, more classical mechanical attachment techniques such as bolting or riveting. It is considered to be competitive primarily because it saves weight, ensures better stress distribution, and offers better aesthetics because the glue line is practically invisible. Applications of bonding by adhesives can be found in many industries, particularly in advanced technological domains such as the aeronautical and space industries, automobile manufacture, and electronics. Adhesives have also been introduced in areas such as dentistry and surgery. However, adhesive joints are not the only application of adhesion. Adhesion is concerned whenever solids are brought into contact, for instance, in coatings, paints, and varnishes; multilayered sandwiches; polymer blends; filled polymers; and composite materials. Because the final performance or use properties of these multicomponent materials depend significantly on the quality of the interface that is formed between the solids, it is understandable that a better knowledge of adhesion phenomena is required for practical applications. The field of adhesion began to create real interest in scientific circles only about 50 years ago. Thus, adhesion became a scientific subject in its own right, but it is still a subject in which empiricism and technology are slightly ahead

563. Tretinnikov, O.N., and Y. Ikada, “Dynamic wetting and contact angle hysteresis of polymer surfaces studied with the modified Wilhelmy balance method,” Langmuir, 10, 1806-1814, (May 1994).

The dynamic wetting behavior of poly(tetrafluoroethylene) (PTFE), polyethylene (PE), polypropylene (PP), poly(ethylene terephthalate) (PET), nylon 6, poly(ether urethane) (PU), poly(vinyl alcohol) (PVA), and cellulose was studied by the Wilhelmy balance technique at speeds of immersion from 1 to 50 mm/min. The Wilhelmy method was modified so as to determine contact angles without extrapolation of the loop to the zero immersion depth, employing a rectangular flat sample having a rectangular hole. This modification of the method allowed us to determine the advancing and receding contact angles on the very narrow sample area close to the lower (first) and the upper (second) sample-hole boundaries, theta1 and theta2, respectively. The interaction time of the sample part located at the lower boundary with the wetting liquid (water) was twice as long as that of the upper boundary. No difference was observed between the advancing contact angles measured at the lower and the upper parts of the sample (theta(ADV,1) = theta(ADV,2)) for all the Polymers, displaying that the dried polymer surfaces had no difference in wettability along the sample length. However, the lower part of the sample became more hydrophilic than the upper part during the wetting measurement for PET, PU, nylon 6, PVA, and cellulose, resulting in the difference between the receding contact angles (theta(REC,1) < theta(REC,2)). The effect was attributed to the time-dependent surface reorientation of hydrophilic and hydrophobic groups, occurring upon immersion of the polymer sample in water. A close correlation was observed between the hysteresis of the contact angle and the underwater surface reconstruction of polymers: the strongest hysteresis corresponds to the greatest wettability gradient generated by the time-dependent reorientation process. However, even when the effect of reorientation was zero (PTFE, PE, and PP) or very low (cellulose), the observed hysteresis was still as high as 27-degrees. The contribution of the surface reorientation of polar groups to the observed hysteresis was estimated to amount to 0-25-degrees, depending on the chemical structure of the polymer investigated. The speed of the sample immersion had no detectable effect on the wettability of PTFE, PE, and PP. On the other hand, the advancing contact angle on PET, PU, and nylon 6 increased while the receding contact angle decreased, as the immersion speed became higher. This behavior may be accounted for by referring to a model of macromolecular dynamics at the three-phase boundary.

149. Hahn, M.T., “Ceramic rollers for corona treating,” Flexo, 19, 134-136, (May 1994).

407. no author cited, “Drying, curing, treatment follow technology leads,” Paper Film & Foil Converter, 68, 24-28, (Apr 1994).

383. Weiss, H., “Surface tension flexo condition being studied,” Paper Film & Foil Converter, 68, 10, (Apr 1994).

92. Fay, M.J., and T.D. Allston, “Characterization of vapor deposited aluminum coatings on oriented polypropylene films,” TAPPI J., 77, 125-129, (Apr 1994).

2390. Williams, R.L., and C.A. Mueller, “Apparatus and method for treating the interior surfaces of hollow plastic objects for improving adhesive properties,” U.S. Patent 5290489, Mar 1994.

1271. Farley, J.M., P. Meka, “Heat sealing of semicrystalline polymer films, III. Effect of corona discharge treatment of LLDPE,” J. Applied Polymer Science, 51, 121-131, (Jan 1994).

The effects of corona-discharge treatment (CDT) of commercial polyethylene (PE) Linear low-density PE (LLDPE) were studied with special emphasis on the heat-seal behavior of treated films. A range of treat levels, representative of those used in industry, was obtained by varying the applied power to a commercial, on-line treater. Film surfaces were characterized by XPS and wetting-tension measurements. The primary effect of CDT on the heat-sealing behavior of LLDPE films is a transition in the failure mode of heat seals from a normal tearing or inseparable bond to a peelable seal. In addition, CDT increases the seal initiation temperature 5–17°C and decreases the plateau seal strength 5–20% as the treat level, or wetting tension, increases from 31 to 56 dynes/cm. These effects are attributed to cross-linking during corona treatment, which restricts polymer mobility near the surface and limits the extent of interdiffusion and entaglements across the seal interface. Results of heat-sealing studies with electron-beam-irradiated PE, chemically oxidized PE, and CDT polypropylene (PP) provide indirect evidence for the proposed surface cross-linking mechanism. The effect of commercial levels of slip additives on the heat-seal behavior was also investigated. copy; 1994 John Wiley & Sons, Inc.

921. Podhajny, R.M., “Converters consultant: What causes my ink adhesion to vary on corona treated polyethylene film?,” Converting, 12, 14, (Jan 1994).

382. Weiss, H., “Surface energy can inhibit ink transfer on ceramic rolls,” Paper Film & Foil Converter, 68, 62, (Jan 1994).

52. Chan, C.-M., Polymer Surface Modification and Characterization, Hanser Gardner, Jan 1994.

7. Agler, S., “Are your bottles print ready?Understanding treatments for surface tension,” ScreenPrinting, 84, 100, (Jan 1994).

2938. no author cited, “ASTM D724: Standard test method for surface wettability of paper (angle-of-contact method),” ASTM, 1994.

2752. Ping-yi Tsai, P., “Mechanism of corona electrostatic charging of nonwoven webs,” in 1994 Nonwovens Conference Proceedings, TAPPI Press, 1994.

2187. Smith, R.E., “Suggested treatment levels (included on company's Infoboard),” Diversified Enterprises, 1994.

2091. Sheng, E., I. Sutherland, D.M. Brewis, and R.J. Heath, “An X-ray photoelectron spectroscopy study of flame treatment of polypropylene,” Applied Surface Science, 78, 249-254, (1994).

X-ray photoelectron spectroscopy (XPS) has been used to study the effects of flame treatment on three propylene polymers, i.e. a homopolymer, an ethylene-propylene copolymer and a rubber-modified polypropylene. Angle-resolved XPS has shown an enrichment in oxygen concentration at the near surface for all three propylene polymers when treated with a mild flame. A depletion in oxygen has been shown at the near surface of the rubber-modified polypropylene treated with an intense flame. The use of simple surface composition models shows that the oxidation depth induced by a mild flame treatment is around 50 Å, and that oxygen-containing functional groups may have reoriented or migrated a few ångströms away from the near surface of the rubber-modified polypropylene during the treatment with an intense flame.

1909. Khairallah, Y., F. Arefi, J. Amouroux, D. Leonard, and P. Bertrand, “Surface fluorination of polyethylene films by different glow discharges. Effects of frequency and electrode configuration,” J. Adhesion Science and Technology, 8, 363-381, (1994) (also in Plasma Surface Modification of Polymers: Relevance to Adhesion, M. Strobel, C.S. Lyons, and K.L. Mittal, eds., p. 147-166, VSP, Oct 1994).

1908. Inagaki, N., S. Tasaka, and K. Hibi, “Improved adhesion between plasma-treated polyimide film and evaporated copper,” J. Adhesion Science and Technology, 8, 395-410, (1994) (also in Plasma Surface Modification of Polymers: Relevance to Adhesion, M. Strobel, C.S. Lyons, and K.L. Mittal, eds., p. 275-290, VSP, Oct 1994).

1906. Poncin-Epaillard, F., B. Chevet, and J.-C. Brosse, “Reactivity of a polypropylene surface modified in a nitrogen plasma,” J. Adhesion Science and Technology, 8, 455-468, (1994) (also in Plasma Surface Modification of Polymers: Relevance to Adhesion, M. Strobel, C.S. Lyons, and K.L. Mittal, eds., p. 167-182, VSP, Oct 1994).

1905. Owen, M.J., and P.J. Smith, “Plasma treatment of polydimethylsiloxane,” J. Adhesion Science and Technology, 8, 1063-1075, (1994) (also in Polymer Surface Modification: Relevance to Adhesion, K.L. Mittal, ed., p. 3-16, VSP, May 1996).

1904. Collaud, M., P. Groening, S. Nowak, and L. Schlapbach, “Plasma treatment of polymers: The effect of the plasma parameters on the chemical, physical, and morphological states of the polymer surface and on the metal-polymer surface interface,” J. Adhesion Science and Technology, 8, 1115-1127, (1994) (also in Polymer Surface Modification: Relevance to Adhesion, K.L. Mittal, ed., p. 87-100, VSP, May 1996).

1903. Zhang, J.-Y., H. Esrom, U. Kogelschatz, and G. Emig, “Modification of polymers with UV excimer radiation from lasers,” J. Adhesion Science and Technology, 8, 1179-1210, (1994).

Photochemical dry etching and surface modification of various polymers, e.g. polymethylmethacrylate (PMMA), polyimide (PI), polyethyleneterephthalate (PET) and polytetrafluoroethylene (PTFE) were investigated with coherent and incoherent excimer UV sources. Ablation rates of PMMA were measured as a function of laser fluence and laser pulse at the wavelength λ = 248 nm (KrF*). Decomposition and etch rates of PMMA and PI were determined as a function of UV intensity and exposure time at three different wavelengths λ = 172 nm (Xe*2), λ = 222 nm (KrCl*) and λ = 308 nm (XeCl*). The transmittance of the polymeric films was determined with a UV-spectrophotometer after different exposure times. The morphology of the exposed polymers was investigated with scanning electron microscopy (SEM). The gaseous products occurring during UV exposure were measured using mass spectrometry (MS). Chemical surface changes of the photoetched PMMA were determined by X-ray photoelectron spectroscopy (XPS). The mechanism of the photo-oxidation process of PMMA is discussed. The etching of PMMA can be explained as a result of extensive photo-oxidation. The results are compared with those obtained from mercury lamp and excimer laser experiments. Good adhesion of electrolessly deposited metal layers was achieved by irradiation of the polymeric surfaces from incoherent UV source before depositing the metal layer.

1901. Shanahan, M.E.R., and J.M. Di Meglio, “Wetting hysteresis: Effects due to shadowing,” J. Adhesion Science and Technology, 8, 1371-1380, (1994) (also in Fundamentals of Adhesion and Interfaces, D.S. Rimai, L.P. DeMejo, and K.L. Mittal, eds., p. 225-234, VSP, Dec 1995).

Wetting hysteresis due to isolated surface heterogeneities is now fairly well understood but when the solid presents a population of defects, complex cooperative effects between neighbours may exist. One such effect is that of ‘shadowing’, in which a proportion of the flaws near the triple line, and which would otherwise contribute to hysteresis, are masked by already existing deformations to the wetting front caused by neighbouring heterogeneities. This renders them inactive and, as a result, the hysteretic wetting force is only expected to be a linear function of density for sparse populations. Theoretical predictions are compared with experimental results obtained with model heterogeneous surfaces consisting of overhead projector transparencies bestrewn with circular ink spots - the defects. Agreement is found to be satisfactory when intrinsic angles on both the homogeneous solid and the flaws are finite, whereas the concordance is less satisfactory when the contact angle of the liquid on the homogeneous solid is zero.

1880. Onyiriuka, E.C., “Electron beam surface modification of polystyrene used for cell cultures,” J. Adhesion Science and Technology, 8, 1-9, (1994).

The surface chemistry of polystyrene, used as tissue culture ware, subjected to electron beam irradiation was studied. Core-level and valence-band (VB) X-ray photoelectron spectroscopy (XPS) showed that electron beam (EB) treatment resulted in surface oxidation plus sterilization of the polymer material. The extent of oxidation by EB is linear with the dose and, as such, is analogous to gamma-radiation-induced oxidation. The data indicate that EB-radiation treatment alone provides a polystyrene surface analogous to that obtained by corona discharge or plasma plus low gamma sterilization.

1879. Sheu, G.S., and S.S. Shyu, “Surface modification of Kevlar 149 fibers by gas plasma treatment,” J. Adhesion Science and Technology, 8, 531-542, (1994).

Kevlar 149 fibers have been surface treated with NH3-, 02-, or H2O-plasm to modify the fiber surfaces. SEM (scanning electron microscopy) is used to characterize the surface topography of fibers etched by gas plasmas. The chemical compositions and functional groups of the fiber surfaces are identified by ESCA (electron spectroscopy for chemical analysis) and SSIMS (static secondary ion mass spectroscopy), respectively. The contact angle of water on modified PPTA [poly(p-phenylene terepbthalamide)] film prepared from using Kevlar 149 fibers is also used to investigate the wettability. The results show that the etching abilities of gas plasmas are dependent on the type of gas used for plasma treatments. The contact angle data indicate that all the three gas plasma treatments are effective in rendering the surface of PPTA more hydrophilic. The ESCA analysis results show that the surface compositions of plasma-treated fibers are highly dependent on the type of gas used and treatment time. Changes in surface compositions of fibers treated by NH3-, O2-, and H2O-plasma are observed. Increasing nitrogen and oxygen contents are observed for the NH3-plasma treatment, and the O2- and H2O-plasma treatments, respectively. Furthermore, the incorporation of amino groups into fiber surfaces by NH3-plasma treatment and the extensive damage of the aromatic ring and the polymer backbone by H2O-plasma and O2-piasma are evidenced by SSIMS.

1878. Sheu, G.S., and S.S. Shyu, “Surface modification of Kevlar 149 fibers by gas plasma treatment, II: Improved interfacial adhesion to epoxy resin,” J. Adhesion Science and Technology, 8, 1027-1042, (1994).

Kevlar 149 fibers were surface-modified by NH3, O2, and H2O plasmas to improve the adhesion to epoxy resin. Poly(p-phenylene terephthalamide) (PPTA) film prepared from Kevlar 149 fibers was also modified to estimate the changes in surface energy caused by the plasma treatments. The interfacial shear strength (IFSS) between the fiber and epoxy resin was measured by the microbond pull-out test. The fracture surfaces of microbond pull-out specimens were examined by scanning electron microscopy (SEM) to identify the failure mode of the microcomposites. The results showed that the IFSS of the Kevlar 149 fiber/epoxy resin system was remarkably improved (up to a factor of 2.42) by these plasma treatments and the treatment time was the governing factor in improving the IFSS. After the plasma treatments, the fracture mode of the microcomposites changed from failure at the interface to failure either in the fiber skin or in the epoxy resin. The surface free energy and the work of adhesion of water on the PPTA surface were markedly improved by the plasma treatments. The polar component of the surface free energy and the acid-base (non-dispersion) component of the work of adhesion made an important contribution to the improvement. Some correlations between the IFSS and the surface energies were found.

1815. Mangipudi, V.S., M. Tirrell, and A.V. Pocius, “Direct measurement of molecular level adhesion between poly(ethylene terephthalate) and polyethylene films: Determination of surface and interfacial energies,” J. Adhesion Science and Technology, 8, 1251-1270, (1994) (also in Fundamentals of Adhesion and Interfaces, D.S. Rimai, L.P. DeMejo, and K.L. Mittal, eds., p. 205-224, VSP, Dec 1995).

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.

1786. Carey, D.H., and G.H. Ferguson, “Synthesis and characterization of surface-functional 1,2-polybutadiene bearing hydroxyl or carboxylic acid groups,” Macromolecules, 27, 7254-7266, (1994).

1743. Egitto, F.D., L.J. Matienzo, K.J. Blackwell, and A.R. Knoll, “Oxygen plasma modification of polyimide webs: Effect of ion bombardment on metal adhesion,” J. Adhesion Science and Technology, 8, 411-433, (1994) (also in Plasma Surface Modification of Polymers: Relevance to Adhesion, M Strobel, C.S. Lyons, and K.L. Mittal, eds., p. 231-254, VSP, Oct 1994).

Webs of Kapton 200-H and Upilex-S polyimide films were treated using oxygen plasma prior to sequential sputter deposition of chromium and copper in a roll metallization system. Two plasma system configurations were employed for treatment. In one configuration, the sample traveled downstream from a microwave plasma; in the other, the web moved through a DC-generated glow discharge. For the DC-glow treatment, the potential difference between the plasma and the web, Φf, and relative ion densities, n+, were measured at various values of chamber pressure and DC power using a Langmuir probe. Although samples treated downstream from the microwave plasma were not subjected to bombardment by energetic ions, Φf for the DC-glow operating conditions was between 5 and 13 eV. For both films, advancing DI water contact angles of less than 20° were achieved using both modes of treatment. Contact angles for untreated films were greater than 60°. However, 90° peel tests yielded values of 15 to 20 g/mm for microwave plasma treatments and 40 to 60 g/mm for DC-glow treatment. Peel values for untreated Kapton and Upilex films were about 25 g/mm. High-resolution X-ray photoelectron spectroscopy in the C1s region for Kapton film surfaces treated downstream from the microwave plasma showed increases in carbonyl groups, with concentrations inversely proportional to web speed. In contrast, DC-glow modification was due mainly to formation of carboxylates with a small increase in carbonyl component. It is proposed that treatment downstream from the microwave plasma results in formation of a weak boundary layer at the polyimide surface. Ion bombardment occurring in the DC-plasma configuration results in relatively more crosslinking at the polymer surface. Furthermore, adhesion between the sputter-deposited chromium and the DC-glow modified polyimide improved with increasing values of Φfn+.

1481. Ghali, K., B. Jones, and J. Tracy, “Experimental techniques for measuring parameters describing wetting and wicking in fabrics,” Textile Research J., 64, 106-111, (1994).

Once capillary pressure and permeability are determined for saturations ranging from near zero to 100%, liquid transport related to both wicking and wetting behavior can be described by Darcy's equation. The purpose of the work reported here is to assess and develop experimental techniques that allow capillary pressure and per meability to be measured over a wide range of saturations. Cotton and polypropylene fabrics are the test materials. Capillary pressure head is measured as a function of saturation for cotton and polypropylene fabric samples using the column test, and permeability is measured as a function of saturation using the siphon test. The siphon test works for cotton but not for polypropylene. A new method using a transient measurement technique is developed to determine the permeability of both samples as a function of saturation; it works well for both samples.


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