Surface plasma

The plasma surface treatment of ETEE to improve adhesion has been studied (34). 

Surface Modification. Plasma surface modification can include surface cleaning, surface activation, heat treatments, and plasma polymerization. Surface cleaning and surface activation are usually performed for enhanced joining of materials (see Metal SURFACE TREATMENTS). Plasma heat treatments are not, however, limited to high temperature equiUbrium plasmas on metals. Heat treatments of organic materials are also possible. Plasma polymerization crosses the boundaries between surface modification and materials production by producing materials often not available by any other method. In many cases these new materials can be appHed directly to a substrate, thus modifying the substrate in a novel way. 

Under normal operating conditions the first wall must handle high plasma surface heat fluxes (Table 1), as well as volumetric heat loadings due to the penetrating neutron and electromagnetic radiation. The volumetric heat loading is dependent... 

This fascinating product will still continue to develop to accommodate new applications, safety, health and environment (SHE) issues, advantages of novel materials like nano-composites, plasma-surface-modified carbon black, development of computer simulation techniques, and finally to develop a cybernetic or thinking tire. 

Xu, Z.N., Losur, S., and Gardner, S.D., Epoxy resin filled with tire rubber particles modified by plasma surface treatment, J. Adv. Mater., 30, 11, 1998. 

Nuclear Fusion Research Understanding Plasma-Surface Interactions... 

C. Parameter Control At present, the most serious impediment to routine use of plasma etching is the large number of parameters that affect the process. As noted, both gas phase considerations and plasma-surface interactions must be controlled. The problem is illustrated in Figure 7 32). Naturally, if the basic plasma parameters (A, /(e), r) could be con-... 

Brown, J.R., P.J.C. Chappell, Z. Mathys (1991), Plasma surface modification of advanced organic fibers part I. Effects on the mechanical, fracture and ballistic properties of aramid/aramid composites. J. Mater. Sci. 26. 4172 178,... 

Donnet, J.B., Dong, S, Guilman, G., Brcndle, M. (1988). Carbon fibers electrochemical and plasma surface treatment. In Proc. ICCl-U, Interfaces in Polymer. Ceramic and Metal Matrix Composites (H. Ishida cd.), Elsevier Sci. Pub., New York, pp. 35-42. 

Plasma surface treatment of many polymers, including fabrics, plastics, and composites, often occurs. The production of ultra-thin films via plasma deposition is important in microelectronics, biomaterials, corrosion protection, permeation control, and for adhesion control. Plasma coatings are often on the order of 1 100 nm thick. 

Emphasis will also be placed on approaches which lead to the removal of reactive species from the gas phase as well as the special role of energetic positive ions in plasma-surface interactions. Controlled scavenging of critical species from the gas phase and/or at specific surfaces and the degree of positive ion bombardment at a given surface can in fact result in simultaneous polymerizatidn at one surface and etching at another within the same apparatus. 

Fig. 2.1. Representation of the parameter problem in plasma-surface interaction. n,-electron density, f(E)-electron energy distribution, N-gas density, x-residence time for gas molecules in plasma volume...

Characterization of Plasma-Surface Interactions 2.2.1 Etch Rate or Polymerization Rate Measurements... 

During the plasma surface reaction, the plasma and the solid are in physical contact, but electrically isolated. Surfaces in contact with the plasma are bombarded by free radicals, electrons, ions, and photons, as generated by the reactions listed above. The energy transferred to the solid is dissipated within the solid by a variety of chemical and physical processes, as illustrated in Figure 7.95. These processes can change surface wettability (cf. Sections 1.4.6 and 2.2.2.3), alter molecular weight of polymer surfaces or create reactive sites on polymers. These effects are summarized in Table 7.21. 

O. Auciello, A. Gras-Marti, J. A. Valles-Abarca, and D. L. Flamm, eds., Plasma— Surface Interactions and Processing of Materials, Kluwer Academic... 

M. Strobel, C. S. Lyons, and K L. Mittal, eds., Plasma Surface Modification of Polymers Relevance to Adhesion, Coronet Books, Philadelphia, Pa., 1994. 

M. D. Smith, Practical Applications of Plasma Surface Modification, AlliedSignal Inc., Kansas City, Mo., Dec. 1993, p. KCP-613-5331. 

Plasma surface cleaning (Ar-02) of the metal substrate is critical for good interfacial bonding with the subsequent coating. XPS and IR analyses show that the plasma-deposited silane polymers are essentially polyorganosiloxane in nature. 

The uptake of iron from transferrin into cells has been best studied for reticulocytes, where there is heavy demand for iron for the synthesis of heme. Reticulocytes and, by analogy, other mammalian cells have receptor molecules on their plasma surface which bind transferrin. Characterization of the transferrin receptor from rabbit reticulocytes suggests that it is probably a glycoprotein of molecular weight around 200 000. The number of receptor sites in cells varies in response to the conditions. For example, treatment of K562 cells with the efficient iron chelator desferrioxamine results in an increase in the total number of receptors for transferrin.1142... 

---