| In this paper,The effects of UV irradiation onα-nucleated PP (α-PP),β-nucleated PP(β-PP) and neat PP have been studied at the morphologic,surface structure and mechanical properties.Lower degradability and breaking elongation were found inβ-PP as compared toα-PP and neat PP;an increase in crystallinity on short-time exposure followed by crystallinity decreased with prolonged exposure was detected in all samples,the crystallinity ofβ-PP reached to the maximum 65.5% after 312h exposure,as well as theα-PP reached to the maximum 74.6% after 456h;Theβ-phase content in the crystallinity portion ofβ-PP reached to the maximum 30.9%after 144h exposure,followed by crystallinity decreased with prolonged exposure,α-phase content ofβ-PP increased after short-time decreased,then remained at 48%after 312h exposure.The effects of heating(with and without oxygen) onα-nucleated PP (α-PP),β-nucleated PP(β-PP) and neat PP have been studied at the morphologic and mechanical properties.It is found that there is no visible crack and decrease of molecular weight in all samples during short-time heating.The mechanical properties of all samples didn't change obviously. The crystallinity ofβ-PP and theβ-phase content in the crystallinity portion ofβ-PP increased in short-time heating followed by both decreased with prolonged exposure in all temperature of test.The crystallinity and the portion ofβ-PP changed quickly when the temperature is higher. |
