Title :
Thermally stimulated current study of amorphous oriented PPS
Author :
Mourgues-Martin, M. ; Bernes, A. ; Lacabanne, C. ; Novel, O. ; Seytre, G.
Author_Institution :
Lab. de Phys. des Solides, Univ. Paul Sabatier, Toulouse, France
fDate :
8/1/1992 12:00:00 AM
Abstract :
The influence of aging on relaxation phenomena in poly-p-phenylene sulfide (PPS) has been investigated by TSC spectrometry. In the vicinity of the glass transition temperature, Tg, two relaxation peaks have been observed in amorphous oriented PPS: a secondary peak at 62°C in nonaged PPS and at 45°C in aged PPS; and a primary peak at 93°C in both films. According to differential scanning calorimetry data, they have been associated with the dielectric manifestation of the sub-Tg and Tg transitions, respectively. Each mode has been characterized by a distribution of relaxation times. For the sub-Tg mode with the relaxation times follow a Vogel equation while for the Tg mode they obey a compensation law. The sub-T g modes, which is strongly enhanced upon aging, has been attributed to a diffusion of free volume favored by local order in rigid domains. The Tg mode has been assigned to cooperative movements of sequences of various length in `true´ amorphous regions
Keywords :
ageing; dielectric relaxation; glass transition (polymers); materials testing; polymers; thermally stimulated currents; 45 to 93 C; Tg mode; Tg transitions; TSC spectrometry; Vogel equation; aging; amorphous oriented PPS; compensation law; cooperative movements of sequences; differential scanning calorimetry data; diffusion of free volume; glass transition temperature; local order in rigid domains; poly-p-phenylene sulfide; relaxation peaks; relaxation phenomena; relaxation times; sub-Tg mode; thermally stimulated current study; Aging; Amorphous materials; Dielectrics; Equations; Glass; Immune system; Insulation; Polarization; Spectroscopy; Temperature control;
Journal_Title :
Electrical Insulation, IEEE Transactions on
