Registration Dossier

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.