线性低密度聚乙烯流延膜取向与阻隔性能关系研究  

Study on the Relationship between the Orientation Structure of Linear Low-density Polyethylene Cast Film and Barrier Properties

作　　者：苏萃 任敏巧 郑萃 姚雪容[1] 贾雪飞[1] 侯莉萍[1] 张韬毅[1] 唐毓婧[1] Cui Su;Min-qiao Ren;Cui Zheng;Xue-rong Yao;Xue-fei Jia;Li-ping Hou;Tao-yi Zhang;Yu-jing Tang(SINOPEC,Beijing Research Institute of Chemical Industry,Beijing 100013)

机构地区：[1]中国石油化工股份有限公司北京化工研究院,北京100013

出　　处：《高分子学报》2021年第7期785-796,I0005,共13页Acta Polymerica Sinica

基　　金：中国石油化工股份有限公司科技部项目(项目号217009)资助。

摘　　要：采用广角X射线衍射(WAXD),小角X射线散射(SAXS)和小角激光光散射(SALS)系统地表征了线性低密度聚乙烯(LLDPE)流延膜以及加入成核剂HPN-20E的LLDPE流延膜的多层级凝聚态结构,并研究晶体取向分布与流延膜阻隔性能之间的关系.未加成核剂的流延膜内PE晶体的主要取向为b轴在TDND(流延膜横向-垂直于流延膜方向)平面内的,以b轴为螺旋轴的螺旋状取向,而以b轴沿MD(流延膜机械方向)方向的方式取向的晶体分布较少.成核剂的加入改变了流延膜内晶体的取向分布以及聚集情况,b轴沿ND方向的螺旋状取向(O_(ND))的晶体明显减少,片晶的尺寸、取向程度以及微观尺寸的晶体聚集情况均发生明显变化.发现在结晶度相近的情况下,晶体的取向排列是影响阻隔性能的关键因素,进而提出用一种半定量的取向结构参数R_(ND),即X射线沿着ND方向得到的晶体(110)与(200)晶面的衍射峰面积的比值,表征晶体取向与阻隔性能之间的关系.Wide-angle X-ray diffraction(WAXD),small-angle X-ray scattering(SAXS)and small-angle laser light scattering(SALS)were used to systematically characterize the multi-level condensed matter structure of linear low-density polyethylene(LLDPE)cast films and LLDPE cast films with the nucleating agent HPN-20E.The relationship between the barrier properties and the condensed matter structure of the cast film is studied.It is pointed out that when the crystallinity is similar,the orientation of the crystal is the key factor affecting the barrier,and a quantitative orientation structure parameter R_(ND) is proposed,which is the ratio of the diffraction peak area of(110)crystal plane to the(200)crystal plane when X-ray incident along the ND direction.The relationship between crystal orientation and barrier property is confirmed.The main orientation of PE crystals in the cast film without nucleating agent is the spiral-oriented crystal with b-axis as the helical axis,where b axes are in the TD-ND plane.The PE crystals in the cast film are rarely oriented with the b-axis along the MD direction.The addition of nucleating agent changes the distribution and orientation of the crystals in the cast film.Among the three typical orientations in PE films,the spirally oriented crystals with the b-axis along the ND direction(OND)possess the worst barrier performance.Therefore,when the crystallinity is similar,the lower the OND content,the better the barrier performance of the sample.A larger R_(ND) value indicates a lower OND content with a similar crystallinity.The R_(ND) values of the two PE samples are significantly increased after adding the nucleating agent HPN-20E,indicating that the OND content is significantly reduced,so the barrier performance is improved.The R_(ND) value of sample 7050 increased more with the addition of nucleating agent,so its barrier performance is improved to a greater degree.Moreover,the addition of nucleating agent also changes the size and orientation of the lamellae,and the microscopic aggregation of t

关 键 词：聚乙烯 阻隔 结晶 取向 

分 类 号：TQ325.12[化学工程—合成树脂塑料工业]