Relaxation in Unsaturated Polyester Resins Studied by Thermally Stimulated Depolarization Currents

Investigations involving thermally stimulated depolarization currents were performed on unsaturated polyester resins cured with styrene. Samples containing different amounts of Co octoate promoter were studied. The complex spectra revealed the classical β and the α dipolar relaxations. The peak characterizing the α dipolar relaxation was overlapped by a ρ peak of appreciable magnitude, due to the presence of impurities in the promoter solution [1]. However, study of the elementary spectra as concerns both α and β peaks for various samples containing different amounts of Co octoate demonstrated that the relaxation kinetics, and particularly the values of the apparent activation energies, do not depend on these impurities. This revised version was published online in August 2006 with corrections to the Cover Date.