Polypropylenglykol in lösung,zahlenmittelmolekulargewicht und reibungsverhalten

Molecular weights of poly(propylene glycol) are determined by measurement of the elevation of the condensation temperature and of the boiling temperature. For determination of the condensation temperature elevation, a new apparatus with 8 thermoelements is described. The physically determined M_n-values were somewhat lower than those determined chemically by the hydroxyl number. The solution behaviour of the polymer was tested by diffusion measurements in acectone and benzene. From M_n = 4000 down to very low molecular weights, diffusion coefficients D are observed yielding constant exponents in the relation D = K·M^?b with b = 0.52 for acetone and 0.55 for benzene.