近熔点挤出HDPE片材结晶结构的研究  

Investigation on Crystal Structure of HDPE Sheets Extruded Near the Melting Point

作　　者：郑海丽[1] 赵元旭[1] 刘忠柱[1] 郑国强[1] 刘春太[1] 

机构地区：[1]郑州大学材料科学与工程学院,河南郑州450001

出　　处：《塑料科技》2013年第7期41-45,共5页Plastics Science and Technology

摘　　要：通过挤出工艺制备了高密度聚乙烯(HDPE)片材,并用二维广角X射线衍射(2D-WAXD)、二维小角X射线散射(2D-SAXS)和差示扫描量热法(DSC)研究了挤出温度和螺杆转速对HDPE挤出片材微观结构的影响。结果表明:在近熔点条件下,HDPE中残存的局部有序结构在微弱的剪切作用下并没有促使片材取向,但是结晶度、长周期和片晶厚度均有所增加。这主要是因为残存的局部有序结构不仅能够加快熔体的结晶动力学进程,还能使结晶起始时间提前,从而使HDPE熔体有更长的时间进一步结晶,进而得到了更完善的晶体。另外,在相同挤出温度下,结晶度、长周期和片晶厚度均随螺杆转速的增加而减小,这归因于熔体在料筒中的剪切时间变短。The combined effects of the near melting point（NMP） temperature and screw speed on microstructure of the extruded high density polyethylene（HDPE） sheets were characterized by twodimensional wide-angle X-ray diffraction（2D-WAXD）,two-dimensional small angle X-ray scattering（2D-SAXS） and differential scanning calorimetry（DSC）.The results show that the locally ordered structure maintained near the melting point does not favor orientation of the HDPE sheets when weak shear is applied.However,crystallinity,long period,lamellae thickness of the NMP sheets increase,as compared to that extruded at high temperature.These increments should be ascribed to the fact that the remained ordered structure could significantly enhance the crystallization temperature,thus accelerate the crystallization kinetics,which leaves more time for the NMP melts to further crystallize.Hence,thicker HDPE lamellae or more perfect crystal structure have been obtained in the NMP sheets as well as the increased crystallinity.Meanwhile,the values of crystallinity,long period,lamellae thickness decrease slightly with increasing screw speed.This may be attributed to shorter time when the melt in the barrel was subjected to shear.

关 键 词：近熔点 挤出 高密度聚乙烯 微观结构 

分 类 号：TQ325.12[化学工程—合成树脂塑料工业]