High-performance polymeric hollow fiber membranes fabricated by a green and sustainable route have become the direction of the future. The bimodal microporous structure was green formed via melt spinning–stretching in the polypropylene (PP)/poly(ethylene-co-vinyl alcohol) (EVOH) hollow fiber membranes (PP/EVOH-HFMs) for improving the porosity and retaining the rejection performance. The relationship between the PP lamellar microstructure, the two-phase interface area, and the EVOH island morphology in PP/EVOH hollow fibers and the bimodal microporous structure in PP/EVOH-HFMs under different melt-draw ratios was established. The pore size of the bimodal microporous structure was controlled by regulating the melt-draw ratio. Small micropore sizes increased from 95 to 183 nm, and large micropore sizes decreased gradually from 3916 to 1054 nm with the melt-draw ratios increased. The porosity and pure water flux of PP/EVOH-HFM reached the maximum when the melt-draw ratio was 6000%. Moreover, the models of phase morphology and microstructure of PP/EVOH blends, PP/EVOH hollow fibers, and PP/EVOH-HFMs were built to explain the regulation mechanism of melt-draw ratio on the bimodal microporous structure of membranes.

中文翻译：

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通过熔纺和拉伸制备的具有双峰微孔结构的聚丙烯/聚（乙烯-共-乙烯醇）中空纤维膜的结构调控：熔体拉伸比的作用

通过绿色和可持续的路线制造的高性能聚合物中空纤维膜已成为未来的方向。双峰微孔结构是通过在聚丙烯（PP）/聚（乙烯-共-乙烯醇）（EVOH）中空纤维膜（PP/EVOH-HFMs）中通过熔融纺丝拉伸形成的，以提高孔隙率并保持截留性能. 建立了不同熔体拉伸比下PP/EVOH中空纤维的PP层状微观结构、两相界面面积、EVOH岛形貌与PP/EVOH-HFMs双峰微孔结构之间的关系。双峰微孔结构的孔径通过调节熔体拉伸比来控制。小微孔尺寸从 95 nm 增加到 183 nm，随着熔体拉伸比的增加，大微孔尺寸从 3916 nm 逐渐减小到 1054 nm。当熔体拉伸比为6000%时，PP/EVOH-HFM的孔隙率和纯水通量达到最大值。此外，还建立了 PP/EVOH 共混物、PP/EVOH 中空纤维和 PP/EVOH-HFM 的相形貌和微观结构模型，以解释熔体拉伸比对膜双峰微孔结构的调节机制。