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Octamethyltrisiloxane (L3) is a liquid at ambient temperature and pressure, with a measured melting point of -87.8°C and a measured boiling point of 152.4°C. It has a measured relative density of 0.82 at 20°C, a measured kinematic viscosity of 0.842 mm2/s at 20°C and a measured vapour pressure of approximately 400 Pa and 530 Pa at 20°C and 25°C respectively.

The substance has a measured flash point ranging from 31.5 to 37°C and a measured boiling point of 152.4°C. Variations in the flash point values may be as a result of the variation in the purity of the test substance and the test method used. It has a measured self-ignition temperature of 340°C, and is not explosive and not oxidising on the basis of structural examination.

In contact with water, L3 reacts slowly with a half-life of 329 h (13.7 days) at pH 7, 5.09 h at pH 5 and 9.76 h at pH 9 and 25°C.

The stated half-life is for removal of parent. Complete reaction to the ultimate end products will take longer. The equation for the reaction is stated below:

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

L3 has a measured log Kow of 6.6 at 25°C and a measured water solubility of 0.034 mg/l at 23°C. The substance is not surface active based on structural examination.