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通过熔体挤出拉伸法以两种聚丙烯为原料制备微孔膜.通过考察原料分子量数据发现高分子量聚丙烯(PPH)在高分子量级分(重均分子量>106)含量上大于低分子量聚丙烯(F401).PPH的弛豫时间在相同条件下也远大于F401.红外二向光法结果表明,PPH在相同熔体牵伸比下片晶取向度较F401高.相同加工条件下PPH微孔膜片较F401成孔分布更均匀,孔径尺寸也更均匀.2种微孔膜孔隙率都随熔体牵伸比的增加而提高,微孔分布随着熔体牵伸比的提高和片晶取向度的增加而趋于均匀,孔尺寸也随之区域均匀.研究表明,聚合物树脂中高分子量级分含量是影响预制膜中片晶取向度、冷热拉伸成孔分布和尺寸均匀度的重要影响因素.
The microporous films were prepared by melt extrusion stretching process using two kinds of polypropylene as raw materials.It was found by analyzing the molecular weight data of raw materials that the content of high molecular weight polypropylene (PPH) was higher than that of low molecular weight (weight average molecular weight> 106) Polypropylene (F401) .The relaxation time of PPH is much higher than that of F401 under the same conditions.The result of infrared diatherometry shows that the degree of orientation of PPH is higher than that of F401 at the same melt-draw ratio.The PPH Compared with F401, the distribution of micropore membrane is more uniform and the pore size is more uniform.The porosity of the two kinds of microporous membrane increases with the increase of melt draw ratio. With the increase of melt draw ratio and The degree of orientation of the smectic crystal tends to be uniform and the size of the pores is also uniform in the region. The results show that the content of the high molecular weight fraction in the polymer resin affects the degree of orientation of the crystallites in the preformed film, Degree of the important factors.