Silicone-elastomer

Elastomeric shield materials (ESM) have been developed as low density flexible ablators for low shear appHcations (49). General Electric s RTV 560 is a foamed silicone elastomer loaded with silicon dioxide [7631-86-9] and iron oxide [1317-61 -9] particles, which decomposes to a similar foam of Si02, SiC, and EeSiO. Silicone resins are relatively resistant to thermal decomposition and the silicon dioxide forms a viscous Hquid when molten (50) (see... 

C. P. Wong, Improved Eoom-Temperature Wulconicyed Silicone Elastomers as Integrated Circuit Encapsulants, Polymer Materials for Electronics Applications, American Chemical Society Symposium Series, Washington, D.C., Nos. 184, 171, 1982. 

This comprises composite materials on mica, glass fibre and asbestos bases, impregnated or glued together with silicone resins or silicone elastomer. These materials must not contain any organic fibrous materials such as paper or cloth backing, which is covered under class B and even F insulation systems. 

Budden, G., High temperature properties of silicone elastomers. J. Coated Fabr., 27, 294-308 (1998). 

Suzuki, T. and Kasuya, A., Adhesion of addition-reaction type silicone elastomers. J. Adhes. Sci. Teclmoi, 3(6), 463-473 (1989). 

Deng, Q., Hahn, J.R., Stasser, J., Preston, J.D. and Bums, G.T., Reinforcement of silicone elastomers with treated silica xerogels silica-silicone IPNs. Rubber Chem. Technol., 73(4), 647-665 (2000). 

E. Case V Predicting Crosslink Density Changes in Silicone Elastomers Due to Aging... 

Figure 29 Characteristic variation of crosslink density of silicone elastomers subjected to aging.

Report 137 Silicone Elastomers, P. Jerschow, Wacker-Chemie GmbH. 

In the early time, the excellent gas permeability seemed to make them promising to be contact lenses. However, the poor hydrophilicity of silicone elastomers diminished their apparent utility. 

The resultant tailored interface is often vastly superior for biomedical applications over the native silicone interface. Furthermore, surface modification maintains the low materials cost and favorable bulk properties of the original silicone elastomer. The modification methods can be divided into physical and chemical techniques. 

Flexible foams with oxygen index values of 40-53 were also prepared by the same authors from blends of copolymer IV and a silicone elastomer, (a phenyl vinyl polydimethylsiloxane) [592]. 

TABLE 2 Data Concerning the Silicone Elastomer in Its Different States of Cross-linking... 

TABLE 3 Modulus Data and Spreading Speed, U, for the Silicone Elastomer... 

Viscoelastics Certain silicone elastomers undergo changes in shear modulus under the influence of electric fields, which might be useful in active mechanical damping applications. 

DKR of a-hydroxy ketones with Shvo s catalyst (racemization) and lipase TL (esterification) Lipase encapsulated by silicone elastomer spheres... 

B.T.N. Vu, Interfacial Modification for the Reinforcement of Silicone Elastomer Composites. M. S. Thesis in Chemistry, The University of Cincinnati, 2001. 

Silicone Rubbers or Elastomers These are having high Molecular weight than the fluids. Generally they are polydimethyl siloxanes. General purpose silicone elastomers are made from polydimethyl siloxanes. 

Dimethyl Silicone Elastomers They are having linear polymers of very high Molecular weight within the range of 30,000-7,00,000. In order to prepare these polymers, dimethyl dichlorosilane is made to dissolve in ether and the solution is then mixed with excess of water. 

Some other silicon elastomers include vinyl silicone elastomers, phenyl silicon elastomers, nitrile silicone elastomers, and fluorosilicone elastomers. 

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