亚胺化时间对电纺聚酰亚胺纳米纤维结构和性能的影响

Effects of Imidization Time on the Structures and Properties of Electrospun Polyimide Nanofibers

通过两步法制备聚酰亚胺(PI)纳米纤维,首先采用高压静电纺丝技术制备聚酰胺酸(PAA)纳米纤维,然后在高温下通过不同的亚胺化时间获得PMDA-ODA型PI纳米纤维。利用红外光谱仪、X射线衍射仪、扫描电子显微镜、热重分析仪和力学性能测试仪研究了不同亚胺化时间对PI纳米纤维微观形貌、化学结构、热稳定性以及断裂强度等的影响。结果表明,当亚胺化时间较短时,聚酰胺酸纳米纤维亚胺化并不完全;亚胺化时间达到30min左右时,聚酰胺酸的亚胺化基本完成;随着亚胺化时间的延长,纳米纤维结晶度逐渐增加,纤维变得更细也更加均匀,热稳定性也随之提高,断裂强度和断裂伸长率也有所提高。通过对聚酰亚胺纳米纤维膜进行透气性测试发现,随亚胺化时间延长纤维膜透气性有所提高。

Polyimide nanofiber(PI)was prepared by the traditional two-step process,and the nanofibers of precursor polyamic acid(PAA)were prepared by electro-spinning.The polyimide nanofibers were obtained through thermal imidization of different time.The influences of different imidization time on micro topography,chemical structure,thermostability and mechanical properties,etc of the polyimide nanofibers were studied and characterized by Fourier transform infrared spectroscope(FT-IR),wide angle X-ray diffraction(WAXD),scanning electronic microscope(SEM),thermal gravimetry analysis(TGA)and mechanical measurement.The results show that the imidization of poly(amic acid)nanofibers is not complete for short time but complete for about 30 min.With increasing of the imidization time,the crystallinity of the PI nanofibers increases,the PI nanofibers become more fine and more smooth,the thermostability of polyimide nanofibers is improved,and the break strength and elongation at break of the nanofiber films increase.The gas permeability of the PI nanofiber membranes was tested and the results show that the gas permeability increases with rise of the imidization time.