Efficient Utilization of Atactic Polypropylene in Its Isotactic Polypropylene Blends via 鈥淪tructuring鈥?Processing

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• 作者：Zhengchi Zhang ; Rui Zhang ; Yanfei Huang ; Jun Lei ; Yan-Hui Chen ; Jian-hua Tang ; Zhong-Ming Li
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2014
• 出版时间：June 18, 2014
• 年：2014
• 卷：53
• 期：24
• 页码：10144-10154
• 全文大小：669K
• 年卷期：v.53,no.24(June 18, 2014)
• ISSN：1520-5045

文摘

Atactic polypropylene (aPP) and isotactic polypropylene (iPP) were incorporated into a new blending material with tailored microstructure. Improved mechanical properties were realized through the application of a shear flow field to injection molding aimed at making use of aPP on a large scale. The hierarchic structure of the oscillation shear injection molding (OSIM) parts was characterized through wide-angle X-ray diffraction, small-angle X-ray scattering, and scanning electron microscopy. It was found that a high and homogeneous orientation inner structure, that is, intense shear flow induced shish-kebabs, is successfully obtained in aPP/iPP blends, which can markedly improve the mechanical performance of blends and offset the mechanical properties decline due to the addition of aPP with poor properties. Owing to the tailored microstructure, as 10 wt % aPP is added, the tensile strength and impact toughness of OSIM samples climb from 30.6 MPa and 4.8 KJ/m² for normal injection molded samples to 57.8 MPa and 16.8 KJ/m², respectively. Even when the aPP content reaches 30 wt %, the OSIM samples retain tensile strength of 52.8 MPa and impact strength of 13.1 KJ/m² compared to only 20.2 MPa and 7.3 kJ/m² for normal samples. This shows the potential for practical applications because of the satisfactory properties of blends and efficient utilization of aPP. In addition, we found that the practical tensile strength of OSIM samples is significantly higher than the theoretical value calculated through mixing principle. For normal samples, an opposite behavior is observed. Although the addition of aPP usually will lead to a remarkable degradation of mechanical properties, it plays a positive role in modifying the inner structure of injection-molded blend samples when structuring processing is used to provide continuous shear flow during processing. Through OSIM technique, we successfully turn 鈥渨aste鈥?into wealth, which opens a new field for efficient usage of aPP and oil resources.