Registration Dossier

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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Physical & Chemical properties

Endpoint summary

Administrative data

Description of key information

Additional information

Decamethyltetrasiloxane (L4) is a liquid at ambient temperature and pressure, with a melting point of <-20°C and a boiling point of 194°C. It has a density of 0.85 g/cm3at 20°C, a kinematic viscosity of 1.3 mm2/s at 20°C and measured vapour pressures of 52 Pa and 73 Pa at 20°C and 25°C respectively.

The substance is classified as a flammable liquid using a conservative approach since the flash point is close to the flammability classification cut-off of ≤60°C according to the criteria of EC Regulation 1272/2008. The substance has a measured flash point of 62 - 63°C and boiling point of 194°C. It has a measured auto-ignition temperature of 350°C and is not explosive and not oxidising on the basis of structural examination.

In contact with water, L4 reacts slowly, half-lives of 14 h at pH 5, 728 h at pH 7, and 21.1 h at pH 9 and 25°C according to the following equation:

(CH3)3SiO[Si(CH3)2O]2Si(CH3)3+ 2H2O → 2(CH3)3SiOH + 2(CH3)2Si(OH)2

The substance has a measured water solubility of 6.7E-03 mg/l at 23°C and a measured log Kow of 8.21 at 25.1°C. The substance is not surface active based on examination of the chemical structure.