Elastomers, solid

Fig. 12. Schematic representation for an elastomer/solid interface strengthened by the addition of end-grafted chains...

These surface-anchored layers can be used as adhesion promoters to enhance elastomer-solid adhesive strength. We have shown that there is then an optimum surface density of surface anchored chains to do so. At high coverage of the surface, the layers lose their efficiency, a tendency which can be rationalized in terms of interdigitation between the elastomer and the surface chains. A full characterization of the different regimes of adhesion enhancement associated with the different regimes of interdigitation between the surface chains and the elastomer is a difficult experimental task, not fully accomplished to date. 

Toso-CSM TS-430 Toso-CSM TS-530 Toso-CSM TS-930 elastomer, solid-surface coatings Toso-CSM TS-340... 

Litvinov, V. M., Strain-Induced Phenomena in Amorphous and Semicrystalline Elastomers. Solid State NMR Relaxation under Uniaxial Compression. Macromolecules 2001, 34,8468-8474. 

Figure 2.7. Schematic representation of Kolafik rnicromechanical model used to calculate Young s modulus of segmented poljmrethaue elastomers. Solid black rectangles represent hal d phase domains. Percolated hai d phase has effective volume fraction, and the rest of the hard domains ai e dispersed in the soft phase matrix [33]...

Foam Production This is important in froth-flotation separations in the manufac ture of cellular elastomers, plastics, and glass and in certain special apphcations (e.g., food products, fire extinguishers). Unwanted foam can occur in process columns, in agitated vessels, and in reactors in which a gaseous product is formed it must be avoided, destroyed, or controlled. Berkman and Egloff (Emulsions and Foams, Reinhold, New York, 1941, pp. 112-152) have mentioned that foam is produced only in systems possessing the proper combination of interfacial tension, viscosity, volatihty, and concentration of solute or suspended solids. From the standpoint of gas comminution, foam production requires the creation of small biibbles in a hquid capable of sustaining foam. 

The water reaction evolves carbon dioxide and is to be avoided with solid elastomers but is important in the manufacture of foams. These reactions cause chain extension and by the formation of urea and urethane linkages they provide sites for cross-linking, since these groups can react with free isocyanate or terminal isocyanate groups to form biuret or allophanate linkages respectively (Figure 27.5). 

JKR type mea.surement.s on monolayers depo.sited on. soft elastomers. The recent interest in the JKR experiments has been stimulated by the work of Chaudhury and coworkers [47-50J. In a 1991 paper, Chaudhury and White-sides [47] reported their extensive studies on the measurement of interfacial work of adhesion and surface energies of elastomeric solids. The motivation for this work was to study the physico-organic chemistry of solid surfaces and interfaces. 

Deruelle, M., Leger, L. and Tirrell, M., Adhesion at the solid-elastomer interface influence of the interfacial chains. Macromolecules, 28(22), 7419-7428 (1995). 

CR adhesives contain 20 wt% solids content. Formulation 100 phr elastomer 4 phr MgO 5 phr ZnO 2 phr hindered phenolic antioxidant 500 phr solvents mixture [2]. 

SBR latex and solid SBR have similar ingredients, except for the use of thickeners (only for latex). The major ingredients, in addition to the elastomer, for the SBR adhesives are given below. 

Wright, P. and Cummings, A., Solid Polyurethane Elastomers. Gordon and Breach, 1969. Buist, J.M. and Gudgeon, H., Advances in Polyurethane Technology. Elsevier, Amsterdam, 1968, p. 72. 

Ceramic materials have found acceptance as cyclone liners for the apex orifice as well as other areas which exhibit severe abrasion. These include areas such as the lower cone liner and vortex finder. Nihard has also proven to be an acceptable wear material, especially for vortex finders and other areas which require strength as well as abrasion resistance. Other elastomer materials such as neoprene and nitrite are also utilized when hydrocarbons are present or when the temperature exceeds 60 °C. Urethane has found acceptance, especially in areas where the solids are relatively fine,... 

Polyurethanes. This material is available in three forms - rigid foam, flexible foam and elastomer. They are characterised by high strength and good chemical and abrasion resistance. The rigid foam is widely used as an insulation material, the flexible foam is an excellent cushion material for furniture and the elastomeric material is used in solid tyres and shock absorbers. 

Block copolymers have become increasingly important in recent decades. This importance is due to the fact that their special chemical structure yields unusual physical properties, especially as far as solid-state properties are concerned. Block copolymers are applied in various fields, they are used as surfactants, adhesives, fibres, thermoplastics, and thermoplastic elastomers. 

Microcellular elastomers16 bridge the gap between solid elastomers and low-density foams. Although they may appear to be noncellular, these materials have a microscopic cell structure and so are by definition high-density foams, with densities between noncellular solids and standard foams. The most commercially important applications include shoe soles, carpet backing, chair armrests,... 

There are many situations where isocyanates are derivatized before use, such as when MDI or TDI are reacted with high-molecular-weight, difunctional polyols to form low-NCO prepolymers used to make cast elastomers by the prepolymer method (Section 4.3.2.1). Because of their molecular weight, prepolymers can be of much higher viscosity than the starting isocyanates, and some are solid at room... 

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