Effect of inorganic filler on thermally stimulated current in low-density polyethylene

By measuring the thermally stimulated current (TSC) spectra at various fields in low-density polyethylene with inorganic filler (f-LDPE) and comparing with those in LDPE, we found that their TSC spectra show significant distinction. In virtue of analysing change of peak current, peak temperature and activation energy with poling field, it can be depicted that the TSC in f-LDPE specimen comes from dipole relaxation of residual silanol groups on surface of filler, but the injected electrons in very high fields, no doubt, are captured in deeper traps, and they can not be released even near 100°C. The filler (kaolin) plays a key role in changing the TSC spectra through deep and interfacial traps existing between the filler and the polymer matrix. Whereas, the TSC spectra of LDPE specimen possess marked characteristics of electron release from traps in amorphous-crystalline or crystalline region.