Microwave dielectric relaxation study of poly(propylene glycol) in dilute solution

Dielectric relaxation studies of poly(propylene glycol), average molecular weight 2000 g mol(-1), in dilute solution of cyclohexane, decaline, benzene and carbon tetrachloride have been carried out at 10.10 GHz and 35 degrees C. Average relaxation time tau (0), and relaxation times corresponding to s egmental motion tau (1), group rotations tau (2) and dipole moment mu have been determined. It is found that tau (0), tau (1) and mu are influenced by the solvent environment while the tau (2) value is solvent-independent. A comparison has been made with the dielectric behaviour of poly(ethylene gly col), average molecular weight 1500 g mol(-1), in dilute solutions of benze ne and carbon tetrachloride because both systems have an equal number of mo nomer units. The effect of methyl side-groups on dielectric relaxation in p oly(propylene glycol) molecules is discussed. The Kirkwood correlation fact or is also evaluated in dilute solutions with concentration variation and i t is found that these molecules exist in cluster form due to intermolecular hydrogen bonding. (C) 2000 Society of Chemical Industry.