Surface structure and chemistry

Carbon/graphite fibers are prepared from either a polyacrylonitrile or rayon precursor fiber or from a pitch precursor 22,23). In either case, the fibers are treated at high 

Metals such as aluminium, steel, and titanium are the primary adherends used for adhesively bonded structure. They are never bonded directly to a polymeric adhesive, however. A protective oxide, either naturally occurring or created on the metal surface either through a chemical etching or anodization technique is provided for corrosion protection. The resultant oxide has a morphology distinct from the bulk and a surface chemistry dependent on the conditions used to form the oxide 39). Studies on various aluminum alloy compositions show that while the oxide composition is invariant with bulk composition, the oxide surface contains chemical species that are characteristic of the base alloy and the anodization bath40 42). 

Overall the surface chemical composition of the reinforcing fibers or the adherends is chemically quite different from the bulk composition of these materials. Specific interactions between epoxies and these surfaces without cognizance of the different surface chemistries can lead to erroneous conclusions about the epoxy-surface bonding or interphase structure. 

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It is obvious from the above results that adsorption of acetic acid, and, of course, presumably other carboxylic acids, is different in detail from one metal oxide to another and is perhaps also somewhat a function of whether adsorption occurs from gas or solution phase. However, in all cases acetate ions are formed and differences presumably reflect more subtle features of surface structure and chemistry. In general, there seems to be a correspondence between the frequencies reported by IR and IETS for IR active modes although intensity patterns are not similar, as one should expect based on the different mechanisms of vibrational excitation. Further work is obviously needed to define the differences between the two spectroscopies more exactly. 

The first and most studied Mossbauer nucleus, iron-57, displays specific catalytic behavior. Mossbauer investigations of supported microcrystallites of iron and its oxide have demonstrated the importance of the techniques in the investigation of surface structure and chemistry. The application to other nuclei that have important catalytic qualities indicates the potential importance of the study of supported microcrystallites by Mossbauer spectroscopy in future investigations of catalysts. Developments in experimental techniques enabling in situ investigations are enhancing the scope of the technique. 

Activated carbons, in spite of their high surface area are not veiy often used as catalyst supports for big scale industrial processes. The reason for this lies in difficulty to maintain the batch quality and also in susceptibility of the carbon surface to air oxidation. On the other hand there are certain feature of the carbon surfaces, which are very unique for this kind of materials. They include the possibility of tailoring the surface structure and chemistry. The latter is related to the nature of metal support interactions. 

Crystal structures and morphologies of aluminas Surface Structures and Chemistry of Aluminas... 

A. Al-Turaif, P. Lepoutre, Evolution of surface structure and chemistry of pigmented coatings during drying. Prog. Org. Coat. 38 (2000) 43—52. 

We can explore the surface structure and chemistry of surfaces at the atomic level because they are so accessible but the problem is keeping them clean. In ceramic processing, surfaces are rarely clean. 

Source Reprinted with permission from Zielke U, Hiittinger KJ, Hoffmann WP, Surface oxidized carbon fibers I. Surface structure and chemistry, Carbon, 34(8), 983-998, 1996. Copyright 1996, Elsevier. 

Phase I Glass surface structure and chemistry, particularly as it relates to the susceptibility to chemical, thermal and physical damage. 

Adsorption mechanisms as they relate to surface structure and chemistry... 

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