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1066. Goodwin, A., “Atmospheric pressure plasma technologies for surface modification of polymers,” in AIMCAL 2003 Fall Technical Conference, AIMCAL, Oct 2003.

2974. Deshmukh, R.R., and N.V. Bhat, “The mechanism of adhesion and printability of plasma processed PET films,” Materials Research Innovations, 22, 283-290, (Sep 2003).

Of the several techniques available for the surface modification, plasma processing has proved to be very appropriate. The low temperature plasma is a soft radiation source and it affects the material only over a few hundred Å deep, the bulk properties remaining unaffected. Plasma surface treatment also offers the advantage of greater chemical flexibility. PET films are widely used for packaging and electrical insulation. The studies of adhesion and printability properties are important. In the present study PET films are treated in air plasma for different time of treatment. The improvement in adhesion is studied by measuring T-peel and Lap shear strength. In addition, printability of plasma treated PET films is studied by cross test method. It has been found that printability increases considerably for plasma treatment of short duration. Therefore it is interesting to study the surface composition and morphology by contact angle measurement, ESCA and AFM. Surface energy and surface roughness can be directly correlated to the improvement in above-mentioned surface related properties. It has been found that the surface oxidation occurs containing polar functional groups such as CSingle BondO, COO. A correlation of all such observations from different techniques gives a comprehensive picture of the structure and surface composition of plasma treated PET films.

2560. Stefacka, M., M. Kando, M. Cernak, D. Korzec, E.G. Finantu-Dinu, et al, “Spatial distribution of surface treatment efficiency in coplanar barrier discharge operated with oxygen-nitrogen gas mixtures,” Surface and Coatings Technology, 174-175, 553-558, (Sep 2003).

The influence of the gas mixture of oxygen and nitrogen on the treatment efficiency distribution is investigated. The treatment efficiency is evaluated by contact angle measurement on polypropylene (PP) samples placed in varying distance from the coplanar barrier discharge electrode module. A planar electrode operated with 4 kHz signal and power of typically 10–21 W is used for treatment. A strong variation of contact angle as a function of distance from the CDB electrode surface is observed for samples treated 4 s in nitrogen discharge. Contact angle changes within 0.3 mm from 37.9 to 62.5° and it reaches 94.1° for 1.5-mm distance. It is already very close to the value of 103° measured on untreated PP. Much smaller treatment depth is obtained for mixture of nitrogen and oxygen. The experiments are performed without gas flow.fferent plasma treatments in a rf

2552. Park, J.-K., W.-T. Ju, K.-H. Paek, Y.-H. Kim, Y.-H. Choi, J.-H. Kim, and Y.-S. Hwang, “Pre-treatments of polymers by atmospheric pressure ejected plasma for adhesion improvement,” Surface and Coatings Technology, 174-175, 547-552, (Sep 2003).

Polymers such as rubbers generally have low surface energy, thus high hydrophobicity and inherent low bondability. An atmospheric pressure ejected plasma (APEP) source is developed for pre-treatments of polymers to overcome these intractable properties and improve the adhesion ability between polymers as environmental-friendly and simple alternative methods to conventional treatments in spite of several limitations until now. Proper operational conditions are found by T-peel tests performed with various plasma parameters and high peel strength up to 3.5 kgf/cm is achieved at those conditions. Optical emission spectroscopy revealed that the amount of oxygen radicals and gas temperatures are found to be higher at proper conditions in T-peel tests and Fourier transform infrared spectroscopy using attenuated total reflection. Scanning electron microscopy is used for the measurement of surface composition and morphology of pre-treated polymer specimen. These results established the advantage of pre-treatments by APEP source in proper operation conditions when compared to the conventional treatments in terms of improvement of the adhesion ability between polymers.

2520. Lange, J., and Y. Wyser, “Recent innovations in barrier technologies for plastic packaging - a review,” Packaging Technology and Science, 16, 149-158, (Sep 2003).

The barrier solutions presently available on the market all have their drawbacks, e.g. cost, water-sensitivity, opacity or perceived environmental bad-will. At the same time there is a trend to use more plastic-based packaging materials for different applications, e.g. as replacements for metal and glass containers. This situation has stimulated the industry to provide new, more efficient barrier solutions. The innovations go along five major lines: (a) thin, transparent vacuum-deposited coatings; (b) new barrier polymers as discrete layers; (c) blends of barrier polymers and standard polymers; (d) organic barrier coatings; and (e) nanocomposite materials. This paper provides a comprehensive review of the different approaches, outlining the principle behind each barrier technology, its performance, its potential and the companies developing and producing the materials. Copyright © 2003 John Wiley & Sons, Ltd.
https://onlinelibrary.wiley.com/doi/abs/10.1002/pts.621

2414. Kuckertz, C., S. Jacobsen, R. Brandt, K. Landes, and R. Hartmann, “Method of surface treating or coating of materials,” U.S. Patent 6613394, Sep 2003.

Described is a method of treating or coating homogeneously at least a portion of the surface of a material selected from metallic materials having a thickness of less than 100 mum and/or polymeric materials. The method of the present invention comprises exposing at least a portion of the surface of the material to an atmospheric plasma generated by an indirect plasmatron. In the method of the present invention, the surface of the material may undergo at least one of an increase in surface tension, a surface grafting, a surface cleaning and a surface sterilization.

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.

1272. Chen, J., and J.H. Davidson, “Ozone production in the negative DC corona: The dependence of discharge polarity,” Plasma Chemistry and Plasma Processing, 23, 501-518, (Sep 2003).

The rate of production and the spatial distribution of ozone in the negative DC corona discharge are predicted with a numerical model. The results are compared to prior experimental data and to results previously presented by the authors for the positive corona discharge. In agreement with experimental data, ozone production rate in the negative corona is an order of magnitude higher than in the positive corona. The model reveals that this significant difference is due to the effect of discharge polarity on the number of energetic electrons in the corona plasma. The number of electrons is one order of magnitude greater and the chemically reactive plasma region extends beyond the ionization region in the negative corona. The paper also extends our prior modeling effort to lower velocities where the Joule heating reduces ozone production. The magnitude of the reduction is characterized by a new dimensionless parameter referred to as the electric Damkohler's third number(DaIII–e).

1192. Akishev, Y.S., M.E. Grushin, A.E. Monich, A.P. Napartovich, and N.I. Trushkin, “One-atmosphere argon dielectric-barrier corona discharge as an effective source of cold plasma for the treatment of polymer films and fabrics,” High Energy Chemistry, 37, 286-291, (Sep 2003).

The properties of an ac dielectric-barrier corona discharge in argon under atmospheric pressure were studied and the results of testing of this type of gas discharge in the low-temperature treatment of polymer films and fabrics for the purpose of enhancement of their wettability were reported.

1190. Ikada, Y., Surface Modification of Polymers for Metal Adhesion, CRC Press, Sep 2003.

1054. Wolf, R.A., and R.E. Ellwanger, “Inline functional coatings of surfaces via plasma CVD at atmospheric pressure,” in 2003 PLACE Conference and the Global Hot Melt Symposium, TAPPI Press, Sep 2003.

1053. Markgraf, D.A., “What technology should I use to treat my film?,” in 2003 PLACE Conference and the Global Hot Melt Symposium, TAPPI Press, Sep 2003 (also in AIMCAL 2003 Fall Technical Conference, AIMCAL, Oct 2003).

1052. Lahti, J., T. Penttinen, J. Rasanen, and A. Savolainen, “The role of surface modification in digital printing on polymer coated packaging boards,” in 2003 PLACE Conference and the Global Hot Melt Symposium, TAPPI Press, Sep 2003 (also in Polymer Engineering and Science, V. 44, p. 2052-2060, Nov 2004).

905. no author cited, “New approach to plastic surface treatment,” Plastics Technology, 49, 37, (Sep 2003).

2540. Hegemann, D., H. Brunner, and C. Oehr, “Plasma treatment of polymers for surface and adhesion improvement,” Nuclear Instruments and Methods in Physics Research, Section B, 208, 281-286, (Aug 2003).

Different plasma treatments in a rf discharge of Ar, He, or N2 are used to etch, cross-link, and activate polymers like PC, PP, EPDM, PE, PS, PET and PMMA. Due to the numerous ways a plasma interacts with the polymer surface, the gas type and the plasma conditions must be adjusted on the polymer type to minimize degradation and aging effects. Wetting and friction properties of polymers can be improved by a simple plasma treatment, demonstrated on PC and EPDM, respectively. However, the deposition of ultra-thin layers by plasma enables the adjustment of wetting properties, using siloxane-based or fluorocarbon films, and further reduction of the friction coefficient, applying siloxane or a-C:H coatings. Nevertheless, the adhesion of plasma-deposited coatings should be regarded, which can be enhanced by depositing a graded layer.

2291. Gotoh, K., Y. Nakata, M. Tagawa, and M. Tagawa, “Wettability of ultraviolet excimer-exposed PE, PI, and PTFE films determined by the contact angle measurements,” Colloids and Surfaces A: Physicochemical and Engineering Aspects, 224, 165-173, (Aug 2003).

Effects of the exposure of ultraviolet (UV) excimer light on the physicochemical surface properties of polymer films were investigated by contact angle measurements and X-ray photoelectron spectroscopy (XPS). The UV light at wavelength of 172 nm was exposed to polyethylene (PE), polyimide (PI), and polytetrafluoroethylene (PTFE) films in ambient air. The advancing and receding contact angles of water on the unexposed and UV-exposed films were determined by the sessile drop and the Wilhelmy methods as a measure of the wettability. For the PE and PI films, remarkable decrease in the water contact angle was accomplished by the UV exposure of several or several 10 s. The XPS data showed that such increase in the wettability was attributed to the increased atomic oxygen concentration at the film surfaces. The wettability of the PTFE film did not change due to the UV exposure. When the UV-exposed PE and PI films were stored in ambient air, the increase in the water contact angle, i.e. the hydrophobic recovery, was observed over a time scale of several days. It was suggested that the gasification of the low-molecular weight oxidized materials as well as the reorientation and the migration of polymer chains in the oxidized surface layer was responsible for the hydrophobic recovery in air. The UV exposure was also attempted to the PI film being covered with a metal mesh to prepare the film having both non-exposed and UV-exposed surface regions. The differences in the advancing and receding contact angles between the both regions were observed on the continuous weight recording at constant interfacial moving velocity by the Wilhelmy method. The Wilhelmy method in combination with the UV lithography technique enabled the simultaneous evaluation of the wettabilities of the treated and untreated surfaces.

903. Chehimi, M.M., A. Azioune, and E. Cabet-Deliry, “Acid-base interactions: Relevance to adhesion and adhesive bonding,” in Handbook of Adhesive Technology, 2nd Ed., A. Pizzi and K.L. Mittal, eds., 95-144, Marcel Dekker, Aug 2003.

2164. no author cited, “Research Report D20-1236: Interlaboratory study to establish precision statements for ASTM D2578, Standard Test Method for Wetting Tension of Polyethylene and Polypropylene Films,” ASTM International, Jul 2003.

1188. Chen, Q., “Investigation of corona charge stability mechanisms in polytetrafluoroethylene (PTFE) teflon films after plasma treatment,” J. Electrostatics, 59, 3-13, (Jul 2003).

In this paper, the corona charge stability in electret polytetrafluoroethylene Teflon film is investigated after the film is treated by radio-frequency plasma. It is found that the charge stability depends strongly on the plasma composition and the film exposure to plasma, especially for negative charge. When a non-metalized film is held horizontally on the ground holder, i.e. with one side facing the plasma, oxygen plasma treatment achieves a superior negative charge retention on the front side, while its rear side retention decreases significantly. Under the same conditions in oxygen/helium and helium plasmas, the charge stability also increases but the potentials are lower compared with pure oxygen plasma after annealing. In a hydrogen plasma, the stability only slightly enhances. If the film is held vertically on the holder, so that both sides contact the plasma, the surface potential on both sides decreases dramatically and arrives at a few volts within 2 min, after annealing at 170°C. By Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS), we conclude that oxidation formed on the front side is responsible for increasing the stability of negative charge. The positive carriers, generated in the film during plasma treatment, recombine with charge from corona charging and causes the surface potential in the rear side of the horizontal non-metalized film, or in both sides of the vertical non-metalized film, to discharge after heating.

2150. Kaplan, S.L., “Cold gas plasmas and silanes,” http://www.4thstate.com/publications/Cold%20Gas%20Plasma%20and%20Silanes, Jun 2003.

2087. Murakami, T.N., Y. Fukushima, Y. Hirano, Y. Tokuoka, M. Takahashi, N. Kawashima, “Surface modification of polystyrene and poly(methyl methacrylate) by active oxygen treatment,” Colloids and Surfaces B: Biointerfaces, 29, 171-179, (Jun 2003).

We examined the possibility of the surface modification of hydrophobic polystyrene (PS) and poly(methyl methacrylate) (PMMA) by ozone aeration, UV irradiation and combination of ozone aeration and UV irradiation (ozone/UV) in distilled water. The surface states of treated films and particles were investigated by means of contact angle, atomic force microscopy (AFM) and FT-IR measurements. According to the contact angle measurements, the values of the contact angle of ultrapure water on treated PS films decreased with an increase in the elapsed time of the treatments. The most remarkable decrease was seen in ozone/UV treatment. On the other hand, the contact angle on treated PMMA films slightly increased to an equal extent after three types of treatments. The film and the particle surfaces of PS with aromatic rings were found to be well modified with hydroxyl (OH) and carbonyl (CDouble BondO) groups and to give the most remarkable effects in ozone/UV treatments, whereas those of PMMA with no aromatic ring were hardly modified, merely resulting in a slight disorder in their surface roughness. The experimental results on surface modification of PS and PMMA revealed that the ozone/UV treatment in distilled water is usable as one of the useful techniques for the surface modification of polymers with aromatic rings.

848. Wang, Y., and S. Rak, “Surface modification of polyphenylene sulfide plastics to improve their adhesion to a dielectric adhesive,” in Adhesion Aspects of Polymeric Coatings, Vol. 2, K.L. Mittal, ed., 121-136, VSP, Jun 2003.

The adhesion strength of a perfluorinated dielectric adhesive to polyphenylene sulfide (PPS) was investigated. The effect of different fillers in the PPS as a function of plasma treatment conditions was evaluated. The change in adhesion as a result of thermal baking was also addressed. The surface composition and surface energy were monitored and systematically quantified by X-ray Photoelectron Spectroscopy (XPS) and contact angle measurements, respectively. The correlations between the presence of certain functional groups, change in surface energy and polarity, and variation in adhesion properties indicate that the adhesion mechanism is mainly due to van der Waals forces. Enhanced wetting at the adhesive/substrate interface and a deeper interfacial diffusion zone are found to be necessary conditions to achieve the optimal adhesion.

847. Iwamori, S., N. Yanagawa, M. Sadamoto, R. Nara, and S. Nakahara, “RF plasma etching of a polyimide film with oxygen mixed with nitrogen trifluoride,” in Polyimides and Other High Temperature Polymers: Synthesis, Characterization and Applications, Vol. 2, K.L. Mittal, ed., 407-418, VSP, Jun 2003.

Oxygen mixed with nitrogen trifluoride (NF3) was used as the gas source for the plasma etching to increase the etching rate of the polyimide (PI) film. In order to investigate the effects of NF3 addition, surfaces of the etched PI films were analyzed with various methods. From the results of x-ray photoelectron spectroscopy (XPS), the chemical bonding state of the etched PI surface with 30% NF3/70% 02 plasma was similar to that of the surface prepared using 100% 02 plasma. The results of FT-IR analyses showed that a part of materials deposited on the etched PI film was soluble in chloroform and it contained carbonyl and ether compounds. Furthermore, the etching products were analyzed using quadrupole mass spectrometry (QMS) and gas chromatography. The main products were found to be H20, HF, CO and C02. In addition, CO/C02 ratio was found to be related to the etching rate which depended on the NF3 concentration.

846. Friedrich, J., G. Kuhn, R. Mix, I. Retzko, V. Gerstung, St. Weidner, R.-D. Schul, “Plasma polymer adhesion promoters for metal-polymer systems,” in Polyimides and Other High Temperature Polymers: Synthesis, Characterization and Applications, Vol. 2, K.L. Mittal, ed., 359-388, VSP, Jun 2003.

The retention of chemical structure and functional groups during plasma polymerisation was investigated. Usually plasma polymer layers, prepared by continuous wave radio-frequency plasma, are often chemically irregular in their structures and chemical compositions. To minimise these irregularities, low wattages and the pulsed plasma technique were applied to avoid fragmentations. The polymerisation of vinyl and acryl-type monomers was strongly enhanced in the dark phase (plasma-off) of a pulsed rf plasma caused by the reactivity of the vinyl or acryl-type double bonds. Bifunctional monomers with acryl or allyl double bonds and also polar groups such as OH, NH2, and COOH were used to produce plasma polymers with defined (regular) structures and a high density of a single type of functional groups. The maximum yields were 30 OH, 18 NH2, 24 COOH groups per 100 C atoms. To vary the density of functional groups a chemical copolymerisation with “chain-extending” comonomers such as butadiene and ethylene was initiated in the pulsed plasma. The composition of these copolymers was investigated by XPS and IR spectroscopy. Homopolymers and copolymer layers were deposited on polypropylene (PP) foils and then aluminium was thermally evaporated. The peel force increased considerably and showed a dependence on the density of functional groups. The plasma polymer deposition was also monitored in situ by the Self-Exciting Electron Resonance Spectroscopy (SEERS) to show correlations between plasma parameters and properties of the deposited plasma polymer layers measured “quasi-in situ” by coupling the plasma chamber with an XPS spectrometer.

2413. Grace, J.M., L.J. Gerenser, C.J. Landry-Coltrain, K.D. Sieber, et al, “High-efficiency plasma treatment of paper,” U.S. Patent 6565930, May 2003.

A method and apparatus are taught for treating paper webs for obtaining the proper surface characteristics to promote adhesion of nonphotosensitive coating materials and/or layers typically coated thereon. The web is passed through a high-voltage sheath region or dark space of the plasma generated by a powered electrode residing in a discharge zone. The frequency of the driving voltage must be above a lower bound dictated by the properties of the paper support and the plasma, and it must be below an upper bound beyond which the sheath voltages drop significantly and it is observed that the benefits of this approach diminish. The dark space is generated by a treatment electrode in a treatment zone. There is a counter electrode having a surface area in said treatment zone which is at least as great as the surface area of the treatment electrode. A power supply is included for driving the treatment electrode with an oscillating high voltage at a frequency less than about 2 MHz and greater than 1/tc where tc is the charging time of a web surface exposed to a rms ion current in the plasma.

1386. Wagner, H.E., R. Brandenburg, K.V. Kozlov, A. Sonnenfeld, P. Michel, J.F. Behnke, “The barrier discharge: Basic properties and applications to surface treatment,” Vacuum, 3, 417-436, (May 2003).

Barrier discharges (BDs) produce highly non-equilibrium plasmas in a controllable way at atmospheric pressure, and at moderate gas temperature. They provide the effective generation of atoms, radicals and excited species by energetic electrons. In the case of operation in noble gases (or noble gas/halogen gas mixtures), they are sources of an intensive UV and VUV excimer radiation. There are two different modes of BDs. Generally they are operated in the filamentary one. Under special conditions, a diffuse mode can be generated. Their physical properties are discussed, and the main electric parameters, necessary for the controlled BD operation, are listed. Recent results on spatially and temporally resolved spectroscopic investigations by cross-correlation technique are presented. BDs are applied for a long time in the wide field of plasma treatment and layer deposition. An overview on these applications is given. Selected representative examples are outlined in more detail. In particular, the surface treatment by filamentary and diffuse BDs, and the VUV catalyzed deposition of metallic layers are discussed. BDs have a great flexibility with respect to their geometrical shape, working gas mixture and operation parameters. Generally, the scaling-up to large dimensions is of no problem. The possibility to treat or coat surfaces at low gas temperature and pressures close to atmospheric once is an important advantage for their application.

809. Greig, S., “Corona treatment - an update for running waterbased inks,” Flexible Packaging, 5, 36-39, (May 2003).

2194. Podhajny, R.M., “Some things to remember about dynamic surface tension,” Paper Film & Foil Converter, 77, 0, (Apr 2003).

1414. Sabreen, S.R., and N. Roobol, “Preparing plastics for painting,” Plastics Decorating, (Apr 2003).

933. Yalkowski, S.H., and Y. He, Handbook of Aqueous Solubility Data, CRC Press, Apr 2003.

698. Nimmer, T.J., and R. Young, “An overview of surface treatment for three-dimensional objects,” ScreenPrinting, 93, 42-45, (Apr 2003).

2553. Park, Y.W., and N. Inagaki, “Surface modification of poly(vinylidene fluoride) film by remote Ar, H2, and O2 plasmas,” Polymer, 44, 1569-1575, (Mar 2003).

The surface modification of poly(vinylidene fluoride) (PVDF) film induced by remote Ar, H2, and O2 plasmas have been investigated using contact angle measurement, X-ray photoelectron spectroscopy, and scanning probe microscope. The contact angle of water shows an improvement in the PVDF surface wettability during short plasma exposure time. Three remote plasmas treated PVDF sheet surfaces occurred dehydrofluorination and oxidation reactions simultaneously. Remote hydrogen plasma was the most effective in defluorination reactions and remote oxygen plasma was unfavorable to abstract fluorine atoms.

1375. Kogelschatz, U., “Dielectric-barrier discharges: Their history, discharge physics, and industrial applications,” Plasma Chemistry and Plasma Processing, 23, 1-46, (Mar 2003).

The capacity of a cold atmospheric-pressure air plasma (CAAP) device for advanced first aid is presented. Using swine as an animal model, two trials: 1) a large, curved cut in hindquarters area and 2) amputation of a front leg, were performed. Cold atmospheric-pressure air plasma effluent, which carries reactive oxygen species (ROS) atomic oxygen (OI), is applied for wound treatments. Swift hemostasis of the wounds by the CAAP treatment was demonstrated. The pressure applied by a finger on the cut arteries in trial 1 and the tourniquet applied in trial 2 could be removed immediately after the treatment and there was no re-bleed in both cases. CAAP hemostasis mechanism was explored via in-vitro tests. The tests on sodium citrate mixed blood-droplet samples show that 1) the heat delivered by the CAAP has no impact on the observed clot formation, 2) plasma effluent activates platelets to promote coagulation state and cascade, and 3) the degree of clotting increases with the total amount of applied OI by means of the CAAP effluent. It took only 16 s of the CAAP treatment to reach full clotting, which was considerably shortened from the natural clotting time of about 25 minutes. The tests on smeared blood samples show that the reduction of the platelet count and the increase of RBC count are proportional to the amount of applied OI. A plausible CAAP hemostasis mechanism is concluded from the in vitro test results and the animal model trials.

1360. Bento, W.C.A., R.Y. Honda, M.E. Kayama, W.H. Schreiner, N.C. Cruz, E.C. Rangel, “Hydrophilization of PVC surfaces by argon plasma immersion ion implantation,” Plasmas and Polymers, 8, 1-11, (Mar 2003).

Commercial polyvinylchloride (PVC) sheets were treated by plasma immersion ion implantation, PIII. Samples were immersed in argon glow discharges and biased with 25 kV negative pulses. Exposure time to the bombardment plasma changed from 900 to 10,800 s. Through contact angle measurements, the effect of the exposure time on the PVC wettability was investigated. Independent of t, all samples presented contact angles, θ, equal to zero after the treatment. However, in some cases, surface hydrophilization was not stable, as revealed by the temporal evolution of θ. Samples bombarded for shorter periods recovered partially or totally the hydrophobic character while the one exposed for the longest time stayed highly hydrophilic. These modifications are ascribed to the Cl loss and O incorporation as shown by XPS measurements. Furthermore, the mobility of surface polar groups and the variation in the cross-linking degree can also affect the PVC wettability.

1254. Strobel, M., V. Jones, C.S. Lyons, M. Ulsh, M.J. Kushner, R. Dorai, M.C. Branch, “A comparison of corona-treated and flame-treated polypropylene films,” Plasmas and Polymers, 8, 61-95, (Mar 2003).

The comparison of corona-treated and flame-treated polypropylene (PP) films provides insight into the mechanism of these surface-oxidation processes. Atomic force microscopy (AFM), contact-angle measurements, and X-ray photoelectron spectroscopy (XPS or ESCA) were used to characterize surface-treated biaxially oriented PP. While both processes oxidize the PP surface, corona treatment leads to the formation of water-soluble low-molecular-weight oxidized materials (LMWOM), while flame treatment does not. Computational modeling of the gas-phase chemistry in an air corona was performed using a zero-dimensional plasma-chemistry model. The modeling results indicate that the ratio of O to OH is much higher in a corona discharge than in a flame. Chain scission and the formation of LMWOM are associated with reactions involving O atoms. The higher ratios of O to OH in a corona are more conducive to LMWOM production. Surface-oxidized PP exhibits considerable thermodynamic contact-angle hysteresis that is primarily caused by microscopic chemical heterogeneity.

684. Mount, E.M. III, “Aluminum adhesion of metallized films in lamination,” Converting, 21, 66-72, (Mar 2003).

683. Cohen, E.D., “Ask AIMCAL: How do I upgrade the laboratory coatings process?,” Converting, 21, 22-23, (Mar 2003).

151. Bhala, M., and L. Dube, “Standardization of polyethylene treatment level using a mathematical model,” Iranian Polymer J., 12, 51-55, (Mar 2003).

A corona discharge treatment of low-density polyethylene film (LDPE) was carried out in preparation for flexographic printing. Such treatment of the PE film is necessary if maximum adhesion of ink is to be achieved. This project involved three different treating machines for which the current had to be manipulated in all the machines so that a standard treatment could be accomplished. Using a mathematical relation, current requirements for each machine were calculated and used to standardize treatment level of PE films. Standardization was achieved by controlling input current in all the three machines so as to attain a treatment level of 38 dynes/cm. This level of treatment showed the best results in adhesion of ink to the PE film during printing. The exercise also confirmed that printing must be carried out within 24 h of treatment since the level of treatment deteriorates with time.

2195. Wolf, R.A., “Atmospheric plasma,” Paper Film & Foil Converter, 77, 44+, (Feb 2003).

1380. Sahil, S., A. Bellel, Z. Ziari, A. Kahlouche, and Y. Segui, “Measure and analysis of potential decay in polypropylene films after negative corona charge deposition,” J. Electrostatics, 57, 169-181, (Feb 2003).

Surface potential decay after negative corona charge deposition has been studied for polypropylene films 50μm thick, over a wide range of decay times and charging voltage (500–2800V). At low initial potential (500–800V), the surface potentials were stable and did not decay. At high initial potential (1200–2800V), the surface potential decay has been clearly observed with differences in the decay rate. The observed decay behavior has been computer simulated to elucidate the transport mechanism in polypropylene films. A good agreement between measured and calculated decay curves was obtained with a model in which charges are transported by hopping of injected carriers between localized trapping centers. The model is characterized by parameters such as the free carrier mobility, the mean free time of carrier between traps and the mean capture time in trap. The transport parameters have been determined by a fitting procedure.

 

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