微注射成型高密度聚乙烯-线性低密度聚乙烯共混物的微结构及力学性能

为提高线性低密度聚乙烯（LLDPE）的拉伸强度和模量，扩大其应用领域，将三种不同相对分子质量的高密度聚乙烯（HDPE）分别与LLDPE共混，通过微注射成型技术制备HDPE-LLDPE制品。综合利用DSC、广角X射线衍射（WAXD）、小角X射线散射（SAXS）和拉伸性能测试研究了共混物在微注射成型过程中的结构演化及力学性能。拉伸测试结果表明，与纯LLDPE相比，HDPE-LLDPE的拉伸强度和模量随HDPE分子量的增加而增加。微结构分析结果显示，随HDPE分子量的增加，HDPE-LLDPE制品的分子链和片晶取向度增大、结晶度增加，且制品内形成了较多取向的Shish-Kebab晶体结构。通过分析微结构的表征结果，解释了HDPE-LLDPE的拉伸强度和模量显著提高的原因。

Microstructure and mechanical properties of high density polyethylene-linear low density polyethylene blends prepared by micro-injection molding

The high density polyethylene (HDPE) with three different molecular weight were blended with linear low density polyethylene (LLDPE) to improve the tensile strength and modulus of LLDPE and expand its application field, and then molded by micro-injection molding to prepare HDPE-LLDPE parts. A combination of DSC, wide-angle X-ray diffraction (WAXD), small angle X-ray scattering (SAXS) and tensile test were performed to provide a comprehensive analysis of microstructure variations and mechanical properties. The tensile test indicates that the tensile strength and modulus of micro-injection molded HDPE-LLDPE parts are enhanced compared with the pure LLDPE. The microstructure characterizations show that the macromolecular and lamellar orientation degree and crystallinity of HDPE-LLDPE increase with increasing molecular weight of HDPE and more highly oriented structure, Shish-Kebab, is formed in HDPE-LLDPE composites. The reasons for considerably enhanced tensile strength and modulus are elucidated based on the analysis of microstructural results.