RESUMO
Dipole-dipole association in mixtures of polyethylene glycol [400] with both propionaldehyde and benzaldehyde, as representative aliphatic and aromatic aldehydes, has been studied. Decreases in molar volume were calculated from density measurements at different temperatures using the intercept method. The results indicated the formation of the associated aggregates in the ratio [2 propionaldehyde: 1 polyethylene glycol] and [1 benzaldehyde: 1 polyethylene glycol], which mean that the association between the aliphatic aldehyde and polyethylene glycol is greater than that for the aromatic aldehyde. This result is in an agreement with the thermodynamic parameters of dielectric relaxation and viscous flow; namely, the apparent activation energy of dielectric relaxation delta H epsilon and the enthalpy of activation of viscous flow delta Hv calculated from dielectric and viscosity measurements for the two systems