原位小角X射线散射研究热拉工艺对熔融拉伸法制备的聚丙烯微孔膜结构的影响

采用原位小角X射线散射和扫描电子显微镜研究了热拉过程中,拉伸比和拉伸温度对熔融拉伸法制备的聚丙烯微孔膜晶体和孔洞结构的影响.研究结果表明,冷拉、热定型过程中片晶簇被分离开,其内部结构在热拉过程中不发生分离等变形;随着热拉拉伸比的增加,片晶簇间架桥长度不断增大;与冷拉、热定型样品相比,热拉后的微孔膜架桥沿垂直于拉伸方向具有较好的周期性.不同的拉伸温度结果表明,架桥长度随拉伸温度升高而增加;温度过高时架桥会发生熔融.

Effect of Hot Stretching on the Structure of Polypropylene Microporous Membranes with in situ Small Angle X-Ray Scattering

With in situ small angle X-ray scattering and scanning electron microscopy measurements, effects of hot stretching temperatures and draw ratios on the lamellae and pore structure of the polypropylene microporous membrane were studied. The results show that the lamellar clusters are separated during the cold stretching and heat setting process, while the internal structures do not undergo separation during the hot stretching process. With the increase of the hot stretching ratio, the bridge length of microporous membrane after hot stretching process increases substantially. Also, it has better periodicity along the equatorial direction compared with the cold-stretching and heat-setting samples. The results of different stretching temperatures show that the length of the bridge increases with the increase of the stretching temperature. When the temperature is too high, the bridge will partially melt. This work can provide guidance for the structural control during preparation of polypropylene microporous membranes.