Studies on the photo-oxidation of PP and PP/mLLDPE blend systems: Thermal, physicochemical, and mechanical Behavior

摘要

The photo-oxidative degradation of the blends of polypropylene (PP) with metallocene linear low density polyethylene (mLLDPE) were studied. The blend samples were exposed to the ultraviolet radiation (UV) for a period of 6 weeks. Tensile mechanical characteristics were derived from stress-strain curves. The changes in crystallinity during exposure were followed by X-ray diffraction (XRD) and differential scanning calorimetry (DSC), whereas the chemical degradation of the blend samples was evaluated by FTIR-ATR. In case of PP, tremendous decrease is observed in tensile strength, elongation at break, and increase is observed in tensile modulus with exposure time. However, with the addition of mLLDPE, UV stability of PP has significantly improved. A significant increase in crystallinity during UV exposure was noted for PP, whereas for PP/mLLDPE (80/20) blend system the crystallinity did not change much. Therefore low level of stabilizers may be required for PP/mLLDPE blend systems. (c) 2007 Wiley Periodicals, Inc.