Microporous membranes obtained from polypropylene blend films by stretching
Microporous membranes obtained from polypropylene blend films by stretching
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DOI：
10.1016/j.memsci.2008.09.001
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发表时间：
2008-12-01
影响因子：
9.5
通讯作者：
Ajji, Abdellah
中科院分区：
文献类型：
--
作者：
Tabatabaei, Seyed H.;Carreau, Pierre J.;Ajji, Abdellah
两种线性聚丙烯（PP.具有不同的分子量），以通过熔融挤出接着拉伸来开发微孔膜。研究了高分子量链对排形核层状结晶的作用。通过广角X射线衍射（WAXD）和傅里叶变换红外光谱（FTIR）测量了晶相和非晶相的取向。使用小角X射线散射（SAXS）获得长周期间距。采用差示扫描量热法（DSC）研究了退火温度和退火过程中的延伸率对薄膜结晶度的影响。发现在140 ℃下退火显著地有助于结晶相的完善。膜表面的扫描电子显微镜（SEM）图像显示出更多的孔密度和均匀的孔径随着高分子量组分的量增加。高M-w PP的加入改善了膜的水蒸气透过率（WVTR），表明孔的互连性增加，这也从膜的横截面SEM显微照片中得到证实。采用BET氮吸附法和压汞法分别测定了微孔膜的比表面积和孔径。探讨了冷拉伸和热拉伸过程中温度和拉伸量对WVTR的影响。在机器和横向方向（MD和TD，分别），以及在正常方向（ND）的耐穿刺性的拉伸性能进行了评价。随着高M-w PP的加入，观察到沿沿着MD和TD的机械性能略有降低，ND没有变化。(C)2008 Elsevier B. V.保留所有权利。
Blends of two linear polypropylenes (PP. having different molecular weights) were prepared to develop microporous membranes through melt extrusion followed by stretching. The role of high molecular weight chains on the row-nucleated lamellar crystallization was investigated. The orientation of crystalline and amorphous phases was measured by wide angle X-ray diffraction (WAXD) and Fourier transform infrared (FTIR). Long period spacing was obtained using small angle X-ray scattering (SAXS). The effects of annealing temperature and applied elongation during annealing on the crystallinity of the films were studied using differential scanning calorimetry (DSC). It was found that annealing at 140 degrees C contributed significantly to the perfection of the crystalline phase. Scanning electron microscopy (SEM) images of the membrane surface showed more pore density and uniform pore size as the amount of high molecular weight component increased. The addition of the high M-w PP improved the water vapor transmission rate (WVTR) of the membranes, indicating increased interconnectivity of the pores, which was also confirmed from cross-section SEM micrographs of the membranes. The surface area and pore dimensions of the microporous membranes were measured using the BET nitrogen absorption technique and mercury porosimetry, respectively. The influences of temperature and amount of stretching during cold and hot stretching on WVTR were also explored. Tensile properties in the machine and transverse directions (MD and TD, respectively) as well as puncture resistance in the normal direction (ND) were evaluated. As the high M-w PP was added, a slight reduction in the mechanical properties along MD and TD and no changes in ND were observed. (C) 2008 Elsevier B.V. All rights reserved.