Study On Poly (Vinyl Alcohol) Nanofibers Prepared Via Electrospinning

Poly (vinyl alcohol) nanofibers were prepared via electrospinning method; the factors influenced the PVA electrospinning process were studied; the optimal conditions to prepare PVA nanofibers were selected. PVA blend PFSA and PVA blend salt nanofiberous catalysts were prepared by electrospinning method; catalytic property of these catalysts to ethyl acetate synthesis were tested. The detailed results are listed as follows.Firstly, using electrospinning method, the effects of different commercial PVAs (FJ1788, SH1788, GD1799) on electrospinnability and nanofiber morphologies were investigated. The spinning solution with different PVAs showed quite different in solution viscosities, conductivities and surface tensions. Three commercial of PVA electrospinnabilities were FJ1788> SH1788> GD1799 under the same conditions. The electrospinnability of GD1799 was efficaciously improved by cosolvent of DMAc. Addition of 20wt% of DMAc enhanced PVA (GD1799) nanofiber morphology.Secondly, pure PVA (FJ1788) were prepared with different spinning condition. PVA nanofiber morphologies and diameter distribution were investigated at the same time. Viscosity and conductivity of PVA spinning increased with PVA concentration; surface tension slightly decreased with PVA concentration. Homogeneous nanofibers with diameter of 128-210nm were prepared with the increasing PVA concentration of 7wt%-11wt%. The morphology of electrospun nanofibers became good when the voltage increased 10kV to 18kV. The average fiber diameter firstly increased and then decreased as increasing the TCD from 5cm to 20cm; and the best fiber morphology was obtained at the TCD of 15cm. The diameter distribution increased as increasing flow rate, and the best fiber morphology was obtained at the flow rate of 0.3ml/h.Thirdly, PVA-PFSA nanofiberous catalysts were prepared by electrospinning method. The effect of spinning condition (PFSA concentration, voltage, TCD, flow rate) on fiber morphologies and diameter distribution were investigated. Ethyl acetate synthesis evaluation showed that all PVA-PFSA nanofiber mats have significantly catalytic property, and the catalytic efficiency is related to the morphology of PVA-PFSA nanofibers. The catalytic effect of the catalyst was slightly decreased after using three times.At last, PVA-salt nano fiberous catalysts were prepared by electrospinning method. PVA-salt nanofiber catalysts have significantly catalytic property; using PVA(9wt%)/NaHSO4(2wt%)/DMAc(35wt%)-H2O(54wt%) as the spinning solution, the spinning condition of 16kV/15cm/0.3ml/h could prepare PVA-NaHSO4 nanofiber catalysts which could reach ethyl acetate conversion rate more than 35%. However, it is difficult to control the spinning process because of the instability. The catalytic effect of the catalyst was decreased after using three times.