熔融拉伸法制备聚丙烯微孔膜成孔机理的原位小角X射线散射研究  

In situ Small Angle X-ray Scattering Study on the Pore Formation Mechanism of Polypropylene Microporous Membranes Prepared by the Melt-stretching Method

作　　者：徐佳丽[1] 孟令蒲[2] 林元菲 陈晓伟[2] 李薛宇 雷彩红[3] 王卫[1] 李良彬[2] 

机构地区：[1]石河子大学化学化工学院,石河子832000 [2]中国科学技术大学国家同步辐射实验室,合肥230029 [3]广东省功能软凝聚态物质重点实验室广东工业大学材料与能源学院,广州510006

出　　处：《高分子学报》2015年第4期403-409,共7页Acta Polymerica Sinica

基　　金：国家自然科学基金(基金号21267020);国家杰出青年科学基金(基金号51325301);国家自然科学基金重大科研仪器设备研制专项(基金号51227801)资助项目

摘　　要：采用熔融拉伸法制备聚丙烯微孔膜,在避免冷拉会自然回缩和热处理后样品需降温检测等因素对冷拉伸样品影响的情况下,在线研究了冷拉、热定型、热拉过程中样品结构变化.原位小角X射线散射检测与扫描电子显微镜、示差扫描量热仪结合深入研究了不同的冷拉拉伸比对微孔膜片晶和孔洞结构的影响.结果表明不同的冷拉伸比其成孔机理不同,冷拉15%,仅拉伸方向长周期发生微弱的变化,其成孔机理是冷拉产生缺陷,热拉成孔;冷拉30%拉伸主要是将薄弱片晶拉伸转变为不稳定的架桥,热定型阶段部分架桥断裂,竖直方向上产生明显的Streak信号;冷拉40%拉伸方向信号显示实际片晶长周期的增长率小于宏观应变,部分骨架片晶在冷拉阶段已被拉伸破坏成孔.随着冷拉拉伸比增大架桥长度变短,孔径减小,30%是制备微孔膜较合适的冷拉拉伸比.t Polypropylene microporous membranes were prepared by melt-extrusion and cold-stretching （MSCS） method. The structure changes of microporous membrane during cold stretching, heat setting and hot stretching were studied in suit to reduce the effect of other factors on cold-stretching samples, such as natural retraction induced by cold stretch and the need of cool detection after heat setting. The influences of coldstretching ratio on micro-lamellae and micropore structure of polypropylene microporous membranes were investigated by in situ small angle X-ray scattering （SAXS）, scanning electron microscope （SEM） and differential scanning calorimeter （DSC）. The results show that different cold-stretching ratios lead to the different hole formation mechanism. Long-period SAXS signals of the meridian direction at the cold-stretching ratio 15% indicate a slight change of macroscopic strain. Thus the corresponding pore formation mechanism is that cold stretching induces micro defects while hot stretching transforms them into micropores. At the cold stretching ratio 30% , small lamellae transform into unstable bridges and part of the bridges break after heat setting. Besides, noticeable signals of streak emerge in the vertical direction. When the cold-stretching ratio is increased to 40% , signals in stretching direction demonstrate that the growth rate of actual lamellar long period is lower than that of macroscopic strain. This phenomenon can be attributed to that partial skeleton lamellae are destroyed by stretching and transformed into bridging crystal fibers. Macro statistics and micro calculations show that the larger the stretching radio, the shorter the length of bridges and the smaller the aperture. Thus the S30 is the most appropriate cold-stretching radio to prepare microporous membranes.

关 键 词：聚丙烯 微孔膜 SAXS 冷拉 热定型 成孔机理 

分 类 号：O632.12[理学—高分子化学]