Electrospinning Of Poly(Arylene Sulfide) Nanofibers

Sub-micrometer or nanometer size fibers (nanofibers) can be generated by electrospinning, in which high voltage to the capillary droplet of polymer solutions or melts to overcome the liquid surface tension to form and draw the jet down to considerably finer fibers. Special properties of the nanofibers are given by structure that their diameters are in the size of 1～1000nm, so they have application potentials in lots of fields, such as high efficiency filtration materials.Recently, more works about researching electrospinning techniques were focused on applications of the nanofibers. There were few researchers paid attentions to the basic principles of electrospinning, mainly works were done by two groups, one was Reneker and his partners, and another was Hohman and his partners. Shenoy, McKee, Yarin, et al investigated the relationship between solution properties and morphology of the nanofibers. The solvent evaporation rate has influence on the solution electrospinnability and fibers morphology, but in the current works of investigation of the basic principal of electrospinning only low boiling point solvent was chosen, there was no report about choosing high boiling point solvent.In this paper, two novel polymers of Poly(arylene sulfide sulfone) (PASS) and m-polyarylene sulfide sulfone amide (PASSA) were chosen for electrospinning. PASS and PASSA can only be dissolved in solvents that have strong polarity and high boiling point. So this paper was aimed at investigating the relationship between electrospinnability or fibers morphology and solution properties with high boiling point of electrospinning condition. 1. Electrospinning equipment was assembled and environment temperature controlling components was introduced. Nanofibers were obtained by electrospinning of high boiling point PASS and PASSA solutions. Different orientation degree nanofibers nonwovens were collected by rotating cylinder collector with different rotating speed.2. The relationship between electrospinnability and rheology properties, conductivity, surface tension, solvent evaporation rate was investigated. The result showed that rheology properties, solvent evaporation rate had important effect on electrospinnability and beads formation.PASS with special viscosity of 0.3441, 0.4349, 0.5363 respectively were dissolved in phenol and 1,1,2,2-tetrachlorothane(volume ratio is 2:3). For all solutions, electrospinnability was depended on theη' . Whenη' was greater than a critical value which was about 0.7-0.9Pa.s, beaded nanofibers was obtained. When PASS was dissolved in high boiling point solvent N-methypyrrolidone (NMP) and solution temperature was 15°C, solution of PASS with concentration of 25wt%,29 wt% could not be electrospun to nanofibers. But when solution temperature was 100°C, both can be electrospun into beaded nanofibers.Nanofibers without beads were obtained by electrospun all of these solutions of PASSA/DMF. Solution of PASSA which was prepared in NMP by adding PASSA at 23wt% concentration had the same rheology properties with the solution of PASSA/DMF at 23wt% concentration. But beaded nanofibers were obtained by electrospun this PASSA/NMP solution for the solvent of NMP with high boiling point.3. Methods for controlling nanofibers diameters were researched. Orthogonal experiments were performed to investigate the relationship between nanofibers diameters and five parameters including solution concentration, environment temperature, tip-to-collector distance, applied voltage and volume flux. Result showed that the solution concentration had greatest influence to nanofibers diameters, so changing solution's concentration was an effective way to control nanofibers diameters. Nanofibers electrospun from high boiling point PASSA/NMP solution had smaller diameters than that from lower boiling point PASSA/DMF solution which had equal real number viscosity. So choosing different boiling point solvent for preparing solution was also a way to control nanofibers diameters.