Abstract
Saturated vapor of commercial pure (monomeric) diphenylmethane diisocyanate (MDI) was generated by the blowing of dry nitrogen at temperatures from 20 to 70°C through flakes of solid monomeric MDI or through the molten chemical. The concentration of MDI in the gaseous phase in the state of equilibrium was determined at the temperatures chosen. The experiments showed that at 50°C the concentration of the saturated vapor of MDI is 1.7±0.2 mg/m3. At 25°C, a concentration of 0.09 mg/m3 (0.009 ppm) can be expected. This is less than 50% of the Threshold Limit Value® (TLV), which has been set for MDI in many countries. By application'of the equation of the state of an ideal gas a vapor pressure of approximately 5–9 × 10−6 mbar in the 20–25°C range was obtained by calculation on the basis of the vapor concentration figures.