Hm. Li et al., THE INFLUENCE OF IONS ON THE THERMALLY STIMULATED DISCHARGE CURRENT SPECTRA OF WATER TREED ADDITIVE-FREE LOW-DENSITY POLYETHYLENE, IEEE transactions on dielectrics and electrical insulation, 1(6), 1994, pp. 1084-1093
The effects of water treeing on steady state de currents and thermally
stimulated discharge current spectra (TSDC) of additive-free low dens
ity polyethylene (LDPE) were studied using heavily water-treed materia
l in solutions of LiCl, LiCl plus HCl, MnCl2 and FeCl3. Significant ch
anges in the de conductivity of treed samples are attributed to the ef
fects of ions. For such samples, graphs of the logarithm of current ve
rsus inverse temperature show three distinct linear regions. The trans
ition temperatures demarcating these regions appear to correlate with
those reported for thermal relaxations. TSDC spectra of water-treed sa
mples show a dependence on both the ionic solutions used and on the po
ling conditions. For LiCl treed samples, twin peaks in the TSDC spectr
a were produced only under specific poling conditions. These peaks may
be correlated with thermal relaxations observed using differential sc
anning calorimetry (DSC). The melting point temperature and the meltin
g peak area derived from DSC spectra were reduced by treeing.