Some physical properties of polyoxymethylene dimethyl ethers

The vapor pressures, liquid density (25°C.), and melting points of the lower members of a homologous series of compounds of simple linear structure have been measured. These are the polyoxymethylene dimethyl ethers, CH 3 O(CH 2 O) n CH 3 , where n = 2 to 5. The heats of vaporiziation derived from the vapor pressures are used in establishing the heat of vaporization of high molecular weight polyoxymethylene. The densities of these compounds allow the density of the high molecular weight liquid polymer (25°C.) to be determined. The values were used for calculating the cohesive energy density of liquid polymer at 104 cal./cc. at 25°C. The limiting heat of vaporization is used with other thermochemical data in the estimation of the lattice energy (heat of sublimation at 0°K.) of polymer; this estimate is 3.8 ± 0.4 kcal./mole of CH 2 O.