辊速辊温对高密度聚乙烯拉伸微孔膜及其片晶结构的影响

EFFECT OF ROLLER RATES AND TEMPERATURES ON THE STRUCTURE OF HDPE STRETCHED MICROPOROUS MEMBRANES AND LAMELLAE

采用熔融挤出片材—退火—冷拉伸—热拉伸—热定形的方法来制备高密度聚乙烯(HDPE)微孔膜,利用FTIR、SEM和DSC等测试方法来研究辊速辊温对HDPE拉伸微孔膜及其片晶结构的影响.研究结果表明,所选树脂的分子量、分子量分布以及弛豫时间能够满足现有加工条件,形成片晶取向度较高的预制膜;在相同辊温下,随辊速增加,退火前预置膜和退火后预制膜的片晶取向度都增加,片晶厚度都降低,拉伸微孔膜中的微孔分布区域增加,微孔结构更加均匀;在相同辊速下,90℃辊温适宜片晶结构的规整排列,在此辊温下得到的预制膜具有最大的片晶取向度、最薄的片晶厚度和最均匀的片晶厚度,拉伸时能得到孔径和微孔分布最均匀的微孔膜.

The HDPE microporous membranes were obtained by a melt-extrusion,annealing,cold stretching,hot stretching and heat setting method.The effect of roller rates and roller temperatures on the structure of the lamellae and the HDPE stretched microporous membranes was characterized by dynamic rheology,FTIR,DSC,SEM and other characterization methods.The results show that the molecular weight,molecular weight distribution and the relaxation time of the HDPE resin used in this experiment can meet the requirements of the present processing conditions for obtaining precursor films with arranged lamellar structure of larger lamellar orientation.Under the same roller temperature,the lamellar orientation of the unannealed and annealed precursor films increases,the lamellar thickness decreases,the micropores distribution regions of the microporous membranes increase and the micropores are more uniform with the roller rates increasing.The lamellar structures arrange more regularly when the roller temperature is 90℃ under the same roller rate,it is a perfect roller temperature to prepare large lamellar orientation precursor films for the resin used in this experiment.Under roller temperature of 90℃,the precursor film with the maximal lamellar orientation,the thinnest lamellar thickness and the narrower lamellar thickness distribution can be obtained,and the structures of the micropore and the micropore distribution are more uniform.