THE INFLUENCE OF IONS ON THE THERMALLY STIMULATED DISCHARGE CURRENT SPECTRA OF WATER TREED ADDITIVE-FREE LOW-DENSITY POLYETHYLENE

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.