Improving the Softness of BOPP Films： From Laboratory Investigation to Industrial Processing

作     者：ling-pu meng xiao-wei chen yuan-fei lin 李良彬 

作者机构：National Synchrotron Radiation Lab Key Laboratory of Soft Matter Chemistry Chinese Academy of Sciences University of Science and Technology of China Hefei 230026 China 

出 版 物：《Chinese Journal of Polymer Science》 (高分子科学（英文版）)

年 卷 期：2017年第35卷第9期

页      面：1122-1131页

核心收录：

学科分类：081704[工学-应用化学] 07[理学] 0817[工学-化学工程与技术] 08[工学] 070205[理学-凝聚态物理] 070305[理学-高分子化学与物理] 080501[工学-材料物理与化学] 0805[工学-材料科学与工程（可授工学、理学学位）] 0703[理学-化学] 0702[理学-物理学] 

基　　金：This work was financially supported by the National Natural Science Foundation of China(Nos.51325301 and 51227801) 

主　　题：Polymer films Stretching processing Processing-structure-property relationship Crystal orientation 

摘      要：Young＇s modulus of biaxially oriented polypropylene （BOPP） films prepared with homemade film stretcher was investigated, which can be used to indicate the softness of films. It was found that the modulus of films was decreased by about 69% as the content of polyethylene （PE） added into polypropylene （PP） reached 30%. Also, increasing draw temperature can induce lower stress level during stretching, which may lead to the formation of crystals with low orientation level and thus decreased modulus of films. Based on laboratory study, BOPP films produced on commercial line were studied by differential scanning calorimetry （DSC）, wide and small-angle X-ray scattering （WAXS, SAXS） with varying contents of PE. SAXS results show that the crystals are oriented in both machine direction （MD） and transverse direction （TD）, and the crystals are more oriented in TD than MD according to the WAXS results for all films. Also, the orientation parameter of crystal along TD increases from 0.68 to 0.83 as the contents of PE increase from 0% to 25%. Meanwhile, the modulus of films in MD declines with increase of PE contents generally, improving the film softness. Orientation of crystals is thus an effective structure parameter to adjust the film softness. The relationship of processing-structure-property is also established.