Silicone fluids, characteristics

Observable Characteristics - Physical State (as normally shipped) Solid or paste in silicone fluid and dibutyl phthalate Color White Odor None. 

We used a new silane which readily permits quantitative conversion of silanol-terminated fluids into aminopropyl-terminated fluids. The reaction between aminopropyl-terminated fluids and diisocyanates proceeds smoothly within a few minutes, either in solution or in the melt. The preparation of siloxane-urea block copolymers is performed in either a two- or a three-component process. By carefully choosing the inorganic segment defined by the corresponding silicone fluid, it is possible to obtain silicone mbbers with different material characteristics. The mechanical properties can be tuned from very soft to very hard. Those materials display tensile strengths up to 14 MPa without requiring additional fillers and can be used for diverse applications. 

The product exhibits a single peak (retention time 5.7 minutes) on a 4-m. gas chromatography column packed with silicone fluid QF on Chromosorb P and heated to 191°. This material has the following spectral characteristics i.r. (CCI4) 1675 (conjugated C==0) and 1623 cm. (conjugated C=C) ... 

The biomedical characteristics of medical grade silicone fluid (liquid polydimethylsiloxanes) have become widely misunderstood. This is primarily because of the publicity given in both the lay and professional press to complications arising from silicone... 

Flockhart, S. M., Dhariwal, R. S. Experimental and numerical investigation into the flow characteristics of channels etched in (100) silicon, ]. Fluids Eng. 120, (1998) 291-295. 

Shen Y, Kumar RS, Pravica M, Nicol ME (2004) Characteristics of silicone fluid as a pressure transmitting medium in diamond anvil cells. Rev Sci Instr 75 4450... 

Over the range 0-200°C the temperature coefficient of viscosity of silicone fluids is only about one tenth of that of mineral oils. In contrast the isoelectronic polymers (Me SiCH ) have normal viscosity characteristics. This means that silicones can be used over very much wider ranges of temperature. Some can still be poured well below — 50°C. Polysiloxane chains are very flexible as noted above for hexamethyldisiloxane, the bond angles in the chains are readily deformed. Moreover there are two mutually perpendicular 2p-3d)n systems which together have approximately cylindrical symmetry about the Si—0 bonds. This means that there is little resistance to torsional motion within the molecule. There is also essentially free rotation of methyl groups about the carbon—silicon bonds. (Barriers to rotation (kjmol" ) About Me—Si, 6.7 Me—C, 15.1 About Si—0, 0.8 C—0.11.3.)... 

An important characteristic of silicone fluids is the relatively small variation of viscosity with temperature (provided, of course, the temperature is not sufficiently high to cause degradation). This property is illustrated in Table 15.3, wherein the viscosities of a silicone fluid and a petroleum oil are compared. The small change in viscosity of silicone fluids stems from the low interaction between chains. 

Because of their thermal stability and low viscosity-temperature coefficient, silicone fluids find use as hydraulic fluids, lubricants and greases. Other applications include textile finishes, mould release agents and anti-foaming agents where water repellency, non-stick characteristics and surface activity respectively are utilized. 

Based on a combination of dimethyl silicone fluid with organic wax side chains. The unique grafted copolymer structure of GP-7102 provides a special range of lubrication and compatibility characteristics, suggesting uses in mold release agents, waxes and polishes, textiles and plastic lubricants, and as an ingredient in oil based metal working fluids. 

To demonstrate the main features of the flow in horizontal CVD reactors, the deposition of silicon from silane is used as an example (87). The conditions are as follows an 8-cm-wide reactor with either adiabatic side walls or side walls cooled to the top wall temperature of 300 K, a 1323 K hot susceptor (bottom wall), a total pressure of 101 kPa, and an initial partial pressure of silane in H2 of 101 Pa. The growth rate of silicon is strongly influenced by mass transfer under these conditions. Figure 8 shows fluid-particle trajectories and spatially varied growth rates for three characteristic cases. 

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