EFFECT OF CaCO3 FILLER ON THE DEGRADATION OF HIGH DENSITY POLYETHYLENE (HDPE) FILM CONTAINING PROOXIDANTS

Abstract

The aim of this work is investigation of effect of CaCO 3 filler on the degradation of high density polyethylene (HDPE) films containing stearate salts as prooxidant additives. The films with thickness of 30 µm were prepared by adding 0.3 wt % prooxidant additives mixture (manganese (II) stearate/ferric stearate/cobalt (II) stearate with ratio of 18:4:1) and CaCO 3 filler from 5 to 20 wt % to HDPE resins by using twin screw extruder. The films were subjected to accelerated weathering treatment according to ASTM G154 standard (340 nm UV lamp, 8 hours UV, 4 hours condensation at 50 o C) for maximum duration of 96 hours. The mechanical properties, Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), thermo gravimetric analysis (TGA) and scanning electron microscope (SEM) were used to assess the changes of films during accelerated weathering. The results showed that the degradation rate of HDPE films with CaCO 3 filler is slower than that of HDPE without CaCO 3 filler, but the higher the CaCO 3 content is, the faster degradation rate HDPE is. After 96 hours of accelerated weathering treatment, the elongation at break of the HDPE film with 5 % CaCO 3 almost unchanged while this value of the HDPE films with 10 and 20 % CaCO 3 decreased significantly (96 % and 100 %, respectively). FTIR spectra of HDPE films with 10 and 20 % CaCO 3 showed carbonyl group's peak as the result of oxidation. FTIR spectra also indicated that CaCO 3 filler did not affect to the mechanism of polyethylene degradation.