Gelest DMS-T21

Chemical Name: Siloxanes and Silicones di-Me
Chemical Family: Silicones, SiloxanesSiliconesSiloxanes

Gelest POLYDIMETHYLSILOXANE, TRIMETHYLSILOXY TERMINATED, 100 cSt (DMS-T21) has good thermal stability. It functions as a diluent and is used in brakes.

Properties

Physical Form: Liquid

Product families

Ready-to-Use Products — Fluids & Lubricants

Greases
Heat Transfer Fluids
Lubricants & Oils

Plastics — Polymer Additives

Rheology Modifiers

Other characteristics

Synonyms: Hexadecanoic Acid
Functions: Diluent
Product Type: Coolant, Dielectric Fluid, Fluid, Grease, Heat Transfer Fluid, Hydraulic Fluids, Release Lubricant; Coolant; Dielectric Fluid; Fluid; Grease; Heat Transfer Fluid; Hydraulic Fluids; Release Lubricant
Application Area: Brakes
Compatible Polymers & Resins: Silicones
Technology: Plastics
Ready-to-Use Products
HIGHLIGHTS: Conventional fluids are the well-known general purpose silicones described in chemical notation as polydimethylsiloxanes. They are commercially produced in viscosities ranging from 0.65 to 2,500,000 cSt.; Conventional silicone fluids are composed of polymer chains with unique flexibility. Polydimethylsiloxane has virtually no energy barrier for rotation. This results in one of the lowest glasstransition temperatures of any polymer.; The liquid surface tension of polydimethylsiloxane is lower than the critical surface tension of wetting (24 dynes/cm). This causes polymers to spread over their own adsorbed films. An important consequence of the low intermolecular forces in polysiloxanes is the highest permeability coefficients of any polymer for oxygen and nitrogen.; The fluids are thermally stable indefinately at 150°C in air. Fluids with viscosities of 50 cSt. or greater have negligible vapor pressure.; At viscosities greater than 1,000 cSt. correlating to molecular weights greater than 30,000, polymer chain entanglement occurs, resulting in leveling of physical property change vs. viscosity. Refractive index, surface tension, density and viscosity-temperature coefficients are strikingly flat.
Standard Packaging: 100 g
3 kg
16 kg
190 kg
Chemical Inventories: TSCA (USA)
Acoustical Properties: Fluid Viscosity (cSt.)
Compatible Polymers and Resins: Silicones
Ready to Use Product Features: General Purpose
Good Thermal Stability
Plastics and Elastomers Functions: Diluent
Polydimethylsiloxanes Properties: Reactivity:; While they exhibit low reactivity under many conditions, certain environments are destructive to silicone fluids. Hydrogen fluoride, for example, attacks the silicon-oxygen bond to produce dimethylsilyl fluorides and water, which generate corrosive gasses. Strong bases such as methanolic potassium hydroxide destroy silicone fluids and create resinous byproducts. Thermal degradation at elevated temperatures causes rearrangement of the silicon-oxygen bonds to product volatile byproducts. Free-radical reaction of the methyl groups to form cross-linked materials by oxidation with peroxy compounds increases fluid viscosity and causes the fluid to gel.; Solubility of Fluids:; Methylene chloride, chlorofluorocarbons, ethyl ether, xylene and methylethyl ketone are typical solvents for dimethylsiloxanes. Low viscosity polymers are also soluble in acetone, ethanol, dioxane and dihexyladipate. They are insoluble in methanol, cyclohexanol and ethylene glycol. The solubility parameter for 100 cSt. fluid is 7.4.; Solubility of Water:; The equilibrium water absorption of silicones is 100-200ppm at 50-85% relative humidity. Drying of fluids is recommended for maximum performance in electrical applications. A typical drying protocol is to apply 1mm vacuum for 1 hour, which typically reduces water levels below 25ppm.

Technical data

Table 1 of 6

5 rows

Characteristic	Value	Unit
Coefficient of Adiabatic Compressibility	1.10 x 10⁻¹⁰	cm2 /dyne
Volume Reduction (of 100 cSt. fluid at 1,000 psi)	0.70 - 0.75	%
Volume Reduction (of 100 cSt. fluid at 10,000 psi)	5.50 - 5.90	%
Volume Reduction (of 100 cSt. fluid at 20,000 psi)	9.00 - 9.20	%
Volume Reduction (of 100 cSt. fluid at 40,000 psi)	13.30 - 13.80	%

Table 2 of 6

11 rows

Characteristic	Value	Unit
Density	0.966	g/ml
Dielectric Strength	400.0	V/m
Refractive Index (at 20°C)	1.4025	—
Viscosity (at 25°C)	100.0	cSt
Viscosity Temperature Coefficient	0.6	—
Pour Point	-65.0	°C
Specific Gravity	0.966	—
Surface Tension	20.9	mN/m
Dielectric Constant	2.75	F/m
Flash Point	315.0	°C
Molecular Weight	5970.0	g/mol

Table 3 of 6

10 rows

Characteristic	Value	Unit
Coefficient of Thermal Expansion	9.3 x 10⁻⁴	°C⁻¹
Thermal Conductivity	3.7 x 10⁻⁴	cal/cm. sec. °C
Specific Heat	0.35 - 0.37	cal/gm/°C
Heat of Formation	-2.41	kcal/gm
Heat of Combustion (>50 cSt.)	6.13	kcal/gm
Glass Transistion Temperature (Tg)	-128.0	°C
Gel Time (at 150°C)	Indefinite	—
Gel Time (for intermediate viscosity fluids at 200°C)	200.0	hours
Gel Time (for high viscosity fluids at 200°C)	100.0	hours
Auto-ignition Temperature (for fluids >10 cSt)	min. 460	°C

Table 4 of 6

2 rows

Characteristic	Value	Unit
Dissipation Factor	0.0001	—
Volume Resistivity (at 20°C)	1x10¹⁵	ohm-cm

Table 5 of 6