The Bacterial Cellulose Dissolution And Electrostatic Spinning Process Research

As a new material gained from bio-fermentation, bacterial cellulose (BC) is applied in many areas including food industry, medical, paper industry and acoustics due to whose unique physics properties and excellent water holding capacity. The properties of BC including the solution in different solvents and the steady rheological properties of BC solution with different concentrations were studied in this research. And also the nanofiber manufactured though electrospinning was observed by SEM.The solution of BC in different solvents such as NMMO, LiCl/DMAc, AmimCl and mixture AmimCl/NMMO was studied in this part. And the solutions with different concentration of BC were obtained in this part which was prepared for next parts (rheological test and electrospinning). The results showed that BC can be dissolved in different solvent which had different solvotation power. The largest concentration of BC in NMMO was 6% (wt/wt) which was 4% in AmimCl,4% in NMMO/AmimCl and 3% in LiCl/DMAc.The result presented that BC solution is pseudoplastic fluid. And the viscosity of BC solution increased with the reducing of shear rate or the reducing of temperature. However, the dependence between viscosity and concentration of BC solution showed a opposed phenomenon. There is a negatively correlation between structure viscosity and temperature. Increasing of shear rate can also reduce the structure viscosity. However, the structure viscosity reduced slightly when the shear rate fell between 225 s-1and 400 s-1. Such reduction became much larger at shear rate up to 400 s-1. Viscosity activity energy of BC solution with higher concentration was lower. Viscosity activity energy of BC solution with different concentrations (0.5%,1.0%,3.0%,3.5%) is 2.8506×104kJ,2.3959×104kJ,2.3268×104kJ and 1.9166×104kJ, respectively.BC nanofibers were obtained from BC/AmimCl solution and BC/NMMO/AmimCl solution by electrospinning from home-made equipment. And the dependences between the morphology of nanofibers and processing factors such as concentration of BC solution, distance, voltage and weight ratio between NMMO or AmimCl with BC were investigated by SEM images. The results showed that diameter of nanofiber is 5μm when the concentration is 2.0%, however no nanofiber was obtained when the concentration is 0.5%. The diameter of nanofiber increased with increasing electrospinning distance. The ratio of solvent could also affect the morphology of nanofiber. The average diameter of BC nanofiber (2%, AmimCl/NMMO=10:0,7:3,4:6) is 300nm,400nm,600nm, respectively.