Synonym: Dimethylcyclosiloxane mixture DMC

In the silicone industry, DMC's full name is Dimethylcyclosiloxane, DMC is a colorless clear and oily liquid, which is formed by cracking the hydrolysate of Dimethyldichlorosilane.  

DMC is a copolymer of polydimethylsiloxane and organic glycol,low Molecular Weight of cyclic siloxane would break the links, then forms the high linear polymer under the catalyst of acid or alkaline. In the process of polymer, polysiloxane of different molecular weights can be produced by controlling the ending agent and the relative concentration of cyclic.

Chemical properties 

  1. Molecular Formula:  [(CH3)2SiO] n, n = 3,4,5,6,7
  2. CAS No.: 69430-24-6
  3. Flash Point: 55℃
  4. Relative Density (water=1.0): 0.95~0.97g/cm3
  5. Appearance: Colorless transparent liquid without visible impurity
  6. Color(Hazen, Pt-Co):10Max.
  7. Refractive index(nD20):1.396-1.397
  8. Acidity(as HCL, %):0.001Max

The DMC molecular structure presents as circularity,  and  mainly consists of  hexamethyl cyclotrisiloxane (D3), octamethyl cyclotetrasiloxane (D4), decamethyl cyclopentasiloxane (D5) and  Dodecamethyl cyclohexasiloxane (D6).

DMC is a kind of colorless, transparent liquid, flammable, odorless, insoluble in water, but dissolve in organic solvents such as benzene, etc. In the primary DMC, the content of D3 and or D4 and or D5 and or D6 are or above 50%.


Dimethylcyclosiloxane (DMC) can be divided into high viscosity, medium viscosity and low viscosity series. DMC is the main intermediate of organosilicon, which polymerizes into organosilicon polymer under the catalysis of acid and alkali, and is used to produce silicone oil, silicone rubber, etc.  In addition, it is also wildly used in hanling silicone rubber packing and cosmetics. The silicone rubber, silicone oil intermediates and other polysiloxane products which are made from DMC can be further processed into various modified silicone rubber and silicone oil with very good high and low temperature resistance, aging resistance and insulating property.