| 초록 |
Stretching of oriented polypropylene (PP) and multilayered PP/PE film to create and enlarge cavities is one of the important steps for the fabrication of porous separator of lithium ion battery.1,2 Herein, we will demonstrate cavitation behavior of oriented PP and multilayered PP/PE films during uniaxial stretch process.3 In-situ small X-ray scattering (SAXS) and wide angle X-ray scattering (WAXS) were used to study the structural evolution of oriented films during uniaxial stretch. Variation of the scattering invariant has been probed and size of a single cavity has been fitted via a cylinder model. For the oriented PP films, two steps including initiation and growth of cavitation can be observed during uniaxial cyclic stretch. In the first step, cavities initiate with a fast-growing rate at the beginning of the cyclic stretch. In the second step, cavities stably grow after ca. 5 cycles. For the stretch of multilayered PP/PE films, the results showed that films with different layers and microstructure were similar in the initiation and growth of microvoids. Thin findings can contribute to a better understanding of the cavitation behavior for the preparation of PP and multilayer PP/PE separators of lithium-ion batteries. (1) B. Xiong et al., Polymer, 128, 57 (2017). (2) B. Xiong et al., J. Membr. Sci., 545, 213 (2018). (3) Z. Chen et al., Polymer, 203, 122832 (2020). |
