The fl relaxations of novolac phenol-formaldehyde (NPF) resin were investigated by whole and partial thermally stimulated depolarization current (t.s.d.c.) measurements in the temperature region from 137 to 270 K. The whole measurements showed two peaks with maximum current at 158 and 187 K, respectively. The peaks obtained by partial polarization were characterized by the activation energy (E,) and relaxation time at the temperature of the peak maximum. The relaxation map and the compensation diagram were drawn. The mean E a for both relaxations is 0.51 eV. The initial part of f12 obeys the compensation law with T~ = 308 K, 26 K below T r The appearance of extremely low convergence of the Arrhenius lines and thus irrational compensation points due to the narrow width of the activation energy (AE,) were discussed. The relaxations are supposed to be caused by the motions of the phenyl rings around the methylene links.
Посилання на статтю:
Investigation of fl relaxation =n novolac phenol-formaldehyde resin by use of thermally stimulated depolarization current / M. Topiñ and Z. Katovi6 // Polymer. – 1994. – Vol 35. – P. 5536-5540.