文章摘要
等规聚丙烯顺序共注射制件的结构与性能
Morphological Structures and Mechanical Properties of iPP Molded by Sequential Co-Injection Molding
  
DOI:10.16865/j.cnki.1000-7555.2017.11.012
中文关键词: 顺序共注射成型  等规聚丙烯  结晶形态  柱晶  力学性能
英文关键词: sequential co-injection molding  isotactic polypropylene  crystalline morphology  cylindritic structures  mechanical property
基金项目:国家自然科学基金资助项目(11372284)
作者单位
王广龙1, 沈俊芳2,3, 侯树森1, 陈静波2,3, 申长雨3 1. 新乡学院 机电工程学院河南 新乡 453003; 2. 郑州大学 材料科学与工程学院河南 郑州 4500013. 郑州大学 橡塑模具国家工程研究中心河南 郑州 450002 
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中文摘要:
      采用顺序共注射成型和传统注射成型对等规聚丙烯进行成型,分别利用偏光显微镜、二维广角X射线衍射以及万能试验机测试制件的结晶形态和力学性能。结果表明,顺序共注射成型过程中表芯熔体之间的强烈剪切使得表芯材料界面处出现柱晶,并且随着延迟时间的延长,柱晶数目增多;顺序共注射成型过程中,表层熔体受到两次剪切以及芯层熔体流动时熔体内部强烈的剪切使得顺序共注射制件内部分子链取向度高,提高了制件的弹性模量和拉伸强度,实现了制件的自增强;顺序共注射制件在拉伸过程中裂纹容易在不同晶体层界面处产生并迅速扩展,从而导致制件断裂,故顺序共注射制件断裂伸长率较传统注射制件有所降低;制件成型过程中剪切形成的β晶能够提高制件的冲击韧性。
英文摘要:
      Isotactic polypropylene (iPP) samples were prepared by sequential co-injection molding (SCIM) and conventional injection molding (CIM). The morphological structures and mechanical properties of the samples were investigated by polarized light microscopy (PLM), two-dimensional wide-angle X-ray diffraction (2D-WAXD) and tensile mechanics test. Results show that cylindritic structures of crystalline morphology are formed in overlap region of skin and core material for strong shear between skin melt and core melt during second injection. As the delay time increases, more cylindritic structures are formed. Due to the higher molecular orientation which is caused by twice shear in skin melt and stronger shear stress in core melt, the elastic modulus and tensile strength of the SCIM samples are improved compared with those of CIM samples. However, SCIM samples are broken easily because of cracks initiated in the interface of different crystal layers of SCIM samples in tensile test, which is verified by the elongation at break of SCIM samples being lower than that of CIM sample. The impact test shows that shear induced β-form iPP can improve the impact strength of samples.
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