Silicone Oils

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Silicone Oils


organosiloxane oligomers or polymers of moderate molecular weight that retain their fluidity throughout a wide temperature range. The most widely used silicone oils are macromolecules with linear (I) or branched (II) structures and capped chain ends, most frequently polydimethylsiloxanes (R = R’ = CH3), polydiethylsiloxanes (R = R’ = C2H5), and polymethylphenylsiloxanes (R = CH3, R’ = C6H5) with molecular weights from several hundred to 30,000.

Silicone oils resemble mineral oils in appearance. They have very valuable properties: hydrophobicity, high compressibility, physical and chemical inertness, relatively small changes in viscosity with temperature, and resistance to high temperatures, even in oxidative mediums.

The coefficient of adiabatic compressibility at 30°C for polydimethylsiloxanes with viscosities of 0.65 and 50 mm2/ sec, or centistokes, are 1.74 × 10-9 sq m per newton (m2/N), or 1.74 × 10-10 cm2/dyne, and 1.09 × 10-9 m2/N, or 1.09X10-10 cm2/dyne, respectively. For ethylene glycol the value is 0.33 × 10-9 m2/N, or 0.33 × 10-10 cm2/dyne.) The viscosity of silicone oils increases appreciably upon compression. They have excellent dielectric properties.

Polydimethylsiloxane oils do not change noticeably upon heating in air up to 175°C; oxidation starts at 200°C. Certain elements (copper, lead, selenium, and tellurium) catalyze the splitting up of the siloxane. Thermal degradation in an inert atmosphere becomes noticeable only above 250°C. Polymethyl-phenylsiloxanes begin to decompose at 250°C in air but only at 300°C in an inert atmosphere.

Silicone oils are synthesized by the same methods as the other polyorganosiloxanes.

Silicone oils are frequently used for water-repellency treatment of glass, ceramics, fabrics, paper, and other materials. They are also used in hydraulic drives and hydraulic clutches; the low viscosity of polydimethylsiloxanes makes possible reduction of the total weight of the hydraulic system by one-half and a decrease in the hydraulic line diameter. High-viscosity silicone oils are used in various damping devices. The high compressibility of organosiloxanes makes possible the production of “liquid springs.” Many silicone oils serve as lubricants or the bases for greases, frequently in combination with petroleum lubricants or synthetic organic lubricating oils. Such lubricants are superior to petroleum lubricants in the stability of their rheological properties over a wide temperature interval.

Silicon oils are often used as liquid dielectrics in transformers, capacitors, and certain radio-electronic parts. They may also be used as foam fire-extinguishing agents, as antiadhesive molding oils, and as fluids for high-vacuum diffusion pumps. They are also used in creams, lotions, and ointments.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
In principle, 5000 mPa x s and 4300 mPa x s silicone oils had more stability than those with 2000 mPa x s.
Silicone oils are used as components in some medications and foods.
ProSolv can be used to remove adhesives, fluxes, pastes, buffing compounds, greases, silicone oils, particulates, resins, waxes and other oils and soils.
The sizing oils are removed through a special green recipe that simultaneously dissolves silicone oils of elastomers, emulsifies the seizing oils of other fibres, cleanses and eliminates any hardness and ions as well as stabilizes the fabric to a suitable pH level.
AdvantaFlex single use assemblies are free of silicone oils and animal-derived ingredients and contain fewer extractables than other tubing.
In the July 2013 issue of the Journal of Pharmaceutical Sciences, scientists at Coriolis Pharma, together with colleagues at Leiden University in The Netherlands and Ludwig Maxmilians University in Germany, published a paper reporting work using RMM and micro-flow imaging to examine the quantitative differentiation of protein particles and silicone oils over a large size range.
8,435,546 B2; Beiersdorf AG, Hamburg, has patented a cosmetic, dermatological or pharmaceutical preparation that is comprised of (a) one or more lipids, which comprise at least one lipid selected from mineral oils, cetearyl isononanoate, caprylic/capric triglycerides, ethylhexyl cocoate, octyldodecanol, cyclic silicone oils, and linear silicone oils: (b) one or more waxes comprising at least one wax selected from beeswax and other insect waxes, paraffin waxes, synthetic waxes, chemically-modified natural waxes, triglyceride waxes, fatty acids, fatty alcohols, candelilla waxes, carnauba waxes, Japan wax, esparto grass wax, cork wax, rice wax, sugar cane wax, flower waxes, leaf waxes from conifers, coffee wax, flax wax, and sesame wax; and (c) one or more gases.
The product is said to be environmentally and user friendly, containing no heavy metals, powders or silicone oils, and is VOC-free.
The product is based on highly viscous silicone oils and PTFE solid lubricants.