通过动态保压注塑成型装置研究剪切场下少量多壁碳纳米管（MWCNTs）对高密度聚乙烯（HDPE）的结晶结构和性能的影响。拉伸测试结果表明,普通注塑成型下MWCNTs含量为1.8%的HDPE/MWCNTs与纯HDPE相比,拉伸强度从28MPa增加到30MPa,冲击强度由22 kJ/m2提高至29 kJ/m2;而剪切场下成型的HDPE和HDPE/MWCNTs样品,其拉伸强度分别达到49MPa和63MPa,同时冲击强度分别为54kJ/m2和69kJ/m2。微观扫描分析显示,普通成型下的HDPE和HDPE/MWCNTs制品内部均呈现出无序的结晶结构,而剪切场下成型的制品内部结晶排列规整,均有串晶状的结晶结构产生。尤其在HDPE/MWCNTs制品中,发现了片晶附生于MWCNTs表面而形成杂化的串晶结构。以上的结果表明,在剪切场下MWCNTs可以明显影响HDPE的结晶和力学性能。
The effect of a small amount of multi-walled carbon nanotubes（MWCNTs） on the crystalline structure and properties of high-density polyethylene（HDPE） was studied using a dynamic-packing injection molding machine.Tensile testing results show that,under conventional injection molding,the tensile strength of both pure HDPE and HDPE/MWCNTs composite（1.8% MWCNTs） is 28 MPa to 30 MPa,respectively;the corresponding impact strength is 22 kJ/m2 and 29 kJ/m2.For HDPE and HDPE/MWCNTs molded under shear flow,the tensile strength is 49 MPa and 63 MPa, respectively,and the corresponding impact strength is 54 kJ/m2 and 69 kJ/m2.The scanning electron microscopy measurements results illustrate that lamellae is randomly distributed in both pure HDPE and HDPE/MWCNTs under conventional injection molding.However,some shish-kebab-like objects were formed under shear flow.Especially in HDPE/MWCNTs,the hybrid crystalline structures were formed due to the epitaxial growth.The above experimental results demonstrate that MWCNTs may affect the crystallization of HDPE and its mechanical properties under shear flow.
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