Thermally stimulated depolarization current of novolac resin

Abstract

A novolac phenol-formaldehyde resin was investigated via the thermally stimulated depolarization current, using integral and partial measurements in the temperature range from 137 to 270 K. Tow broadened peaks, assigned as 131 and 132, appeared at about 160 and 190 K. The influence of water and M n was investigated. The activation energy E a vs. T relationship was analysed, and a search was made for compensation phenomena. The distribution of the relaxing dipoles N vs. E a was approximated. Three different relaxation ranges were distinguished. All the motions were attributed to the rotation of the phenyl rings. The differences found are due to the heterogeneity in the resin. Contamination with water increases the polarizability, decreases the structure differences and relieves the motions in the resin. A resin with a smaller ~, exhibits a higher polarizability and a decreases in structure variety.