LLDPE microparts with 0.2 mm thickness and macroparts with 1.5 mm thickness were prepared by using microinjection molding and conventional injection molding,respectively.Tensile test,differential scanning calorimetry (DSC) and small-angle Xray scattering (SAXS) were performed to provide a comparison study of mechanical properties and microstructure.The tensile test indicates that LLDPE micropart exhibits lower tensile strength and yield strength compared to LLDPE macropart,which is contrary tc the reported results in literatures.Based on thorough analysis of the microstructure results,the reason for unexpected lower tensile strength and yield strength of LLDPE microparts is explored.It is suggested that lower crystallinity,formation of imperfect crystals with thin lamellae and a wide distribution of lamellae thickness lead to the poor mechanical properties in LLDPE microparts.%分别采用微注射成型和常规注射成型技术,制备了厚度为0.2 mm和1.5 mm的线性低密度聚乙烯(LLDPE)制品.通过拉伸性能测试、差示扫描量热法(DSC)和小角X射线散射(SAXS)试验对比,研究了制品的力学性能和微结构.拉伸测试结果表明:微注射成型LLDPE制品相对于传统注射成型LLDPE制品具有较低的拉伸强度和屈服强度,这与文献中报道的结果不一致.通过分析微结构的表征结果发现,微注射成型LLDPE制品具有较低强度的主要原因是LLDPE微制品形成了较多不完善的、片晶厚度较薄的晶体结构,且结晶度较低.
展开▼
