Dimethylsilicone fluid

As a class dimethylsilicone fluids are colourless, odourless, of low volatility and non-toxic. They have a high order of thermal stability and a fair constancy of physical properties over a wide range of temperature (-70°C to 200°C). Although... 

The fluids have reasonably good chemical resistance but are attacked by concentrated mineral acids and alkalis. They are soluble in aliphatic, aromatic and chlorinated hydrocarbons, which is to be expected from the low solubility parameter of 14.9 MPa. They are insoluble in solvents of higher solubility parameter such as acetone, ethylene glycol and water. They are themselves very poor solvents. Some physical properties of the dimethylsilicone fluids are summarised in Table 29.2. 

Dimethylsilicone fluids are used extensively as antifoams although the concentration used in any one system is normally only a few parts per million. They are useful in many chemical and food production operations and in sewage disposal. 

The columns in vapour phase chromatographic apparatus usually incorporate high molecular weight dimethylsilicone fluids as the stationary phase. 

Resins, usually in a partially condensed form, are used to provide a water-repellent treatment for brickwork and masonry. Methyl-phenylsilicone resins are used as coatings for eletrical equipment and in the impregnation of class H electrical equipment. Dimethylsilicone fluids are also used as water-repellent coatings for class A or class B insulation. 

N, Al-Dimethylserotonin, 2 92 Dimethylsilanediol biodegradability of, 22 605 in silicone polymerization, 22 556 Dimethylsilicone fluids... 

Fig. 4. Kinematic viscosity—temperature relationship of dimethylsilicone fluids.

ABIL dimethylpolysiloxane dimethylsilicone fluid dimethyl-siloxane Dow Corning Q7-9120 E900 methyl polysiloxane poly(dimethylsiloxane) Sentry. 8 Description Dimethicones are clear, colorless liquids available in various viscosities see Section 4. ... 

Linear poly(dimethylsiloxane)s are used in a number of refinery applications. They are normally trimethylsilyl end-capped polymers of the type MDnM. They are made by reaction of dimethylsilicone fluid (DM) and a source of chain terminator, (CHj SiO- (M). The ratio of M to D controls the molecular weight and viscosity of the product (9). 

Fluorinating dimethylsilicones provides a polymer with greater thermal stability. This type of poly(dimethylsiloxane) is made by equilibrating a fluorinated alcohol with a dimethylsilicone fluid as described in U.S. Pa-... 

A well-known application of the dimethylsilicone fluids is as a polish additive. The value of the silicone fluids in this application is due to its ability to lubricate, without softening, the microcrystalline wax plates. 

High-molecular-weight dimethylsilicone fluids are used as stationary phase for columns in vapor-phase chromatographic apparatus. 

Silicones (RR SiO) have been known since the early part of the twentieth century. Kipping is known for many seminal contributions to mechanistic and preparative organo-silicon chemistry [11]. Silicones, in the absence of acidic or basic catalysts, exhibit exceptional thermal stability. For example, degradation of dimethylsilicone fluids begins at 350°C [12]. This thermal stability is being exploited, for instance, in the seahng of kitchen appliances, hair dryers. 

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