聚四氟乙烯拉伸微孔膜的结构与性能

Structure and Property of Porous Polytetrafluoroethylene Membrane Prepared by Stretching

通过挤出、压延和拉伸等工序制备了聚四氟乙烯微孔膜,采用扫描电镜(SEM)分析了微孔膜的微观结构;采用差示扫描量热法(DSC)和广角X衍射(WXRD)表征了拉伸前后聚四氟乙烯结晶度的变化;研究了拉伸温度、拉伸倍率和拉伸速率对微孔膜力学性能的影响。结果表明:聚四氟乙烯微孔膜具有小岛状结点和与拉伸方向平行的微细纤维组成的微观结构;拉伸使PTFE的结晶度显著降低;拉伸工艺是制备微孔膜的关键因素,拉伸温度220-320℃, 拉伸倍率为8倍时,微孔膜的最大拉伸强度可达8．5 MPa;此外较大的拉伸速率可获得尺寸分布更均匀的微孔。

Porous polytetrafluoroethylene（PTFE） membrane was prepared from PTFE fine powder by extrusion, rolling, and stretching. The morphology and degree of crystallinity of PTFE were analyzed through SEM, DSC, and WXRD. SEM indicated that the membranes consisted of island-like node and micro-fibrils domains with the latter highly oriented in the direction of stretching. In the WXRD spectrum, after heat-treatment the original single diffraction peak split into two overlapped peaks and the intensity was reduced obviously. The effect of stretching temperature, ratio, and rate on the porous membrane＇ s morphology and mechanical properties were also discussed. When the stretching temperature is 220 - 320℃, ratio 8, the maximum tensile strength, 8. with homogeneous cell size distribution is produced with 5 MPa, is achieved. Porous PTFE membrane the increase of tensile rate.