Polyimide Nanofibers Prepared By Electrospinning

Electrospinning is an efficient method to fabricate polymer nanofibers. In recentyears, with the rapid development of nano-technology, various fibers manufactured byelectrospinning have great application values in fields of tissue engineering, filter andprotective material. Polyimide (PI) fiber is a kind of high performance fiber, it hashigh modulus, high temperature resistant, resistant to radiation and many otherexcellent performances.In this work, we use pyromellitic dianhydride (PMDA) and bis (4-aminophenyl)ether (ODA) as monomer to prepare polyamide acid, and utilize high pressureelectrospinning technology to prepare polyamic acid nanofiber-membrane which wasfurther imidized into polyimid nanofiber membrane. In this study, a drum typecollector which can do reciprocating motion in the direction of vertical axis wasdesigned. This collector had increased the collecting area of fibers, and effectivelymade the nonwoven membranes be more uniform. Electrospun polyimide nonwovenmats were prepared at various spinning conditions. In this article, four electrospinningprocess variables were considered，such as the solution concentration, appliedvoltage, tip-to-collector distance, and feed rate of polymer solution. The polyimidefibers were characterized by scanning electron microscopy (SEM), and the fiberdiameter and standard dispersion under different spinning parameters were alsostudied. Infrared analysis (IR), X-ray Diffraction (XRD), porosity measurement andthermogravimetric analysis (TG) were used to analysis and forecast structure.The results showed that image of FTIR was confirmed the imide structure doesexist; PI nonwoven mats were respectively investigated by SEM images. As a result, itwas found that the average diameters of PI nanofibers were from89nm to1025nm;Meanwhile, when the solution concentration, feed rate of polymer solution andapplied voltage were raised or tip-to-collector distance was increased, the averagediameters and uniform degree of PI nanofibers were enlarged; Low Crystallizationof PI nonwoven mats was manufactured by Electrospinning; Porosity of PI non-woven membrane decreases with the increase of fiber diameter; PI nonwoven mats have excellent heat-resistant performance, and the thermal stability is well in300~500℃. However, beaded structure would decrease the decompositiontemperature of PI nonwoven mats.