Atmospheric plasma techniques

Current research into reactive atmospheric plasma techniques for the nanocoating of textile substrates includes a new atmospheric CoatingStar [16] technology for the appHcation of microcapsules [17] in aerosol form. Atmospheric plasma treatments represent an alternative to the (post) treatment of textiles. A schematic representation of the reactive plasma system is illustrated in Figure 7.10. 

Surface cleaning via atmospheric plasma techniques reduces organic contamination on the surface in the form of residues, anti-oxidants, carbon residues, and other organic compounds. Oxygen-based atmospheric plasmas in particular are effective in removing organics whereby mono-atomic oxygen (0", 0 ) reacts with... 

The apphed pretreatment techniques were digestion with a combination of acids in the pressurized or atmospheric mode, programmed dry ashing, microwave digestion and irradiation with thermal neutrons. The analytical methods of final determination, at least four different for each element, covered all modern plasma techniques, various AAS modes, voltammetry, instrumental and radiochemical neutron activation analysis and isotope dilution MS. Each participating laboratory was requested to make a minimum of five independent rephcate determinations of each element on at least two different bottles on different days. Moreover, a series of different steps was undertaken in order to ensure that no substantial systematic errors were left undetected. 

Atmospheric Plasma Spray (Triplex APS). These deposition techniques will be used within this project to deposit the various layers in planar SOFC. 

The various methods of preparation employed to prepare nanoscale clusters include evaporation in inert-gas atmosphere, laser pyrolysis, sputtering techniques, mechanical grinding, plasma techniques and chemical methods (Hadjipanyas Siegel, 1994). In Table 3.5, we list typical materials prepared by inert-gas evaporation, sputtering and chemical methods. Nanoparticles of oxide materials can be prepared by the oxidation of fine metal particles, by spray techniques, by precipitation methods (involving the adjustment of reaction conditions, pH etc) or by the sol-gel method. Nanomaterials based on carbon nanotubes (see Chapter 1) have been prepared. For example, nanorods of metal carbides can be made by the reaction of volatile oxides or halides with the nanotubes (Dai et al., 1995). 

Several methods effectively apply thin coatings to substrates. One process commonly employed for TBC fabrication is thermal plasma spraying. For this technique, the bond coat is deposited with low-pressure plasma spraying, and the Zr02 top coat is then created using atmospheric plasma spraying.A potential problem with this method is coating fracture due... 

Thickness of APS (atmospheric plasma spraying) coating can be selected between 50 and 250 pm, depending on application however, novel deposition techniques such as suspension or solution plasma-spraying allow coatings with thickness <10 pm. 

The detection systems used with HPLC can be broadly divided into three approaches photometry, plasma techniques (ICPAES, ICPMS), and cold vapour atomic absorption and fluorescence spectroscopy (CV-AAS, CV-AFS). The method with the lowest limits of detection (LOD) with sample introduction via a direct injection nebulizer used ICP-MS. An HPLC system coupled to atmospheric pressirre chemical ionization MS was used to identify methyl mercury spiked into a fish tissue CRM (DORM-1, NRCC). This type of system has a significant advantage over elemental detection methods because identification of the species present is based on their structure, rather than matching the analyte s retention time to that of a standard. 

Surface Treatment. Most film surfaces require surface treatment for use in subsequent steps of coating, printing, lamination, or metallization. This treatment results in the chemical modification of the polymer at the surface. The most widely employed surface modification is oxidation of the polymer to create a polar smface (43). Processes that are widely employed are corona and flame treatment. Wet chemical oxidative treatments are seldom used and are restricted to low speed operations. A new surface oxidation technique has been recently developed which uses an atmospheric plasma generated in a hollow cathode with helium or helium gas blends (44). 

Siegel MW, Fite WL. Terminal ions in weak atmospheric plasmas. Applications of atmospheric pressure ionization to trace impurity analysis in gases. J Phys Chem. 1976 80 2871-81. Sunner J, Ikonomou MG, Kebarle P. Sensitivity enhancements obtained at high temperatures in atmospheric pressure ionization mass spectrometry. Anal Chem. 1988 60 1308-13. Thomson BA. Micro and nano-electrospray ionization techniques. In Gross M, Caprioli R, editors. Encyclopedia of mass spectrometry Vol6. Ionization methods. Oxford Elsevier, 2007. pp. 435 4. 

If information about a solid surface free energy (SFE) is needed, contact angle measurements and ink tests are two of the most frequently used methods. Here we present a comparative study of contact angle measurements and ink tests on 13 different materials. We observed major differences in the SFE values obtained by these two techniques and explained the differences on the basis of basic theoretical concepts of both methods. We found that test inks fail to monitor the efficiency of atmospheric plasma treatments on low surface energy solids. Moreover, we determined the polar and dispersion contributions to the test inks total surface tension (ST) in order to provide a more detailed understanding of these methods to determine a solid SFE. 

A number of chemical analysis techniques can be used to characterize atmospheric pollutants. These include atomic absorption, inductively coupled plasma techniques. X-ray fluorescence, neutron activation analysis, and ion-selective elec-... 

Murokh I. Atmospheric Plasma Surface Treatment Technique. El Segundo, CA Tri-Star Technologies 2005. 

In spite of a common use of ozone application together with various surface modification techniques, such as corona and atmospheric plasma, the influence of the combined action on the most popular plastics has not been quantified by exhaustive experimental data. Such a discussion regarding to the use of ozone with corona or of ozone with atmospheric plasma on heat seal strength will follow. 

A recent comparison by Sparavigna [4] of ozone with corona and ozone with atmospheric plasma treatment has revealed an interesting opportunity to further optimize the extrusion coating process for flexible packaging structures. In particular, the study involved two experimental runs, which were performed by coating low-density polyethylene onto oriented polypropylene and polyester film. Ordinary heat seal strength techniques were used to quantify the effects of the variables on heat seal strength vs. seal temperature. 

It is also critical to evaluate the various charged and neutral plasma-introduced species in gas-phase exposures, as well as to identify neutral and charged functional groups on polymeric substrate surfaces, to better understand plasma reaction mechanisms and other physical effects. Continued research in this area will use diagnostic techniques under the atmospheric plasma pressure environment to develop new and improved processes for functionalizing roll polymeric materials surfaces. More advanced laboratory-scale atmospheric plasma installations will also serve to enhance the chemically tailoring effects of industrial scale atmospheric plasma systems. 

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