Study On The Dissolution, Forming Process And Properties Of Bacterial Cellulose

Physical and chemical properties as well as the dissolving properties of bacterial cellulose were studied.A proper kind of solvent was found to prepare bacterial cellulose solution.The theological behavior of the solution was discussed.The optimum processing conditions were got respectively.Based on above research works, the main results obtained were as follows:Bacterial cellulose could be dissolved in lithium chloride/dimethyl acetamide (LiC1/DMAc),polyformaldehyde/dimethyl sulfoxide and N-methylmorpholine-N-oxide after activation.By investigating the dissolution condition and properties of the regenerated cellulose,LiC1/DMAc solvent system,the preferable solvent,was selected for preparing the spinning solution.Activation could greatly enhance the dissolubility of bacterial cellulose.The proper activation conditions were as follows concentration of ethylene diamine 10%, room temperature,activation time 90 minutes.The optimum conditions of dissolving bacterial cellulose in LiC1/DMAc were as follows:content of LiC1 7%,dissolving temperature 80～100℃,agitating time 60minutes,agitation speed 900rmp.Under this optimal condition mentioned above,the dissolubility of 2%bacterial cellulose reached 97.5%.Bacterial cellulose solution was a typical pseudoplastic fluid.The apparent viscosity of solution decreased with the increase of shear rate and temperature.The optimum conditions of preparing bacterial cellulose membrane were as follows:content of bacterial cellulose 2%,coagulation concentration DMAc 30%, coagulation temperature 20℃,coagulation time 9minutes.Under this optimal condition mentioned above,the fiber strength was 16.78MPa and elongation was 98.56%after treated with 20%glycerol for 20 minutes.Regenerated bacterial cellulose membrane with slippery and transparent surface had good water containing,absorption capability and permeability as well as a certain extent of resistance to acid and alkali.Its permeanting rate of light surpassed 95%.Its crystal changed from celluloseⅠtoⅡ,whose crystallinity reduced from 98.6%to 23.4%.Thermal stability of membrane decreased slightly compared with raw material. The optimum conditions of preparing bacterial cellulose fiber were content of bacterial cellulose 2.5%,coagulation concentration DMAc 30%,coagulation temperature 20℃.The stength of bacterial cellulose fiber with the best spinning technique was 2.37cN/dtex.FIIR and XRD photo showed that bacterial cellulose fiber had celluloseⅡcrystal without derivative process.Round cross-section,smooth surface and even distribution was observed in the SEM photograph of the prepared fiber.