Self-Reinforced Isotactic Polypropylene Prepared by Melt Vibration Injection Molding |
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Authors: | Li Youbing Chen Jing Shen Kaizhi |
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Affiliation: | 1. College of Material Science and Engineering, Chongqing Institute of Technology , Chongqing, China;2. College of Polymer Science and Engineering, The State Key Laboratory of Polymer Materials Engineering, Sichuan University , Chengdu, Sichuan, China li-youbing@163.com;4. College of Material Science and Engineering, Chongqing Institute of Technology , Chongqing, China;5. College of Polymer Science and Engineering, The State Key Laboratory of Polymer Materials Engineering, Sichuan University , Chengdu, Sichuan, China |
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Abstract: | Polypropylene (PP) has a good combination of properties, but at low temperatures it is friable and its impact ductility is very low. To improve impact strength, a vibration injection molding (VIM) technology was used to investigate the mechanical properties of polypropylene. Yield strength is upgraded with an increment in vibration frequency and a peak stands at a special frequency for VIM; the elongation at break and impact strength are also enhanced by increased vibration frequency. The wide-angle x-ray diffraction (WAXD) curves and the scanning electronic microscopy (SEM) micrographs have shown that, in the vibration field, the enhancement of mechanical properties is attributed to the occurrence of γ-phase crystals and more pronounced spherulite deformation than those seen in conventional injection moldings (CIM), and the smaller spherulites with the existence of β-phase crystals are favored for improving toughness. With the application of vibration injection molding, the mechanical properties of isotactic PP are improved. To prepare self-reinforcing and self-toughening polypropylene molded parts it has been concluded that high vibration frequency is required. Increasing vibration pressure amplitude obviously significantly improves the yield strength and impact strength. |
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Keywords: | Injection molding Polypropylene Reinforcement Vibration |
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