Study On Spinning Technology Of Polyacrylonitrile/Ionic Liquids Solutions

Polyacrylonitrile(PAN) fiber is used not only in civilian field but also in industry,particularly in the aviation and space fields.But during developed spinning processes of PAN fiber,large amount of deleterious solvents,such as DMSO,DMF,NaSCN(51%H₂0) or HNO₃(67%) etc., are used and these solvents are difficult to be recovered and unfriendly to the environment.Ionic liquids have been recognized as a new class of "green solvents" during the cleaner production process and attracted widespread interest in the scientific community and industry for the unique structure and excellent propertiesFirstly,the rheological behaviors of PAN/1-Butyl-3-methylimi-dazolium Chloride([BMIM]Cl) were discussed.The effect of several factors,including concentration,temperature,molecular weight on both steady and dynamic rheological properties were discussed,which were compared with that of conventional solutions under the same conditions. It is shown that the PAN/[BMIM]C1 solutions belonged to a typical pseudoplastic fluid,whose shear viscosity was larger than that of the conventional solutions.Both the viscosity and elasticity of the solution decrease with increasing temperature and decreasing concentration and molecular weight.The flow-activation energy of PAN/[BMIM]Cl solution was large,which predicted the good spinnability of PAN/[BMIM]Cl solution through comparing with that of conventional solution under the same conditions.Base on the spinnability discussed,the nascent PAN fibers were prepared by dry-wet spinning from PAN/[BMIM]Cl solution.The effect of coagulation conditions(temperature,concentration of coagulation bath and the extrusion stretch ratio) on the structures and properties of nascent PAN fibers was studied.The results showed when the concentration of coagulation bath was 5%,the temperature was 25℃,extrusion stretch ratio was 1.2,both the nascent fibers and the PAN fiber had a perfect structure,and excellent mechanical properties.At last,PAN fibers were prepared under different draw temperature and draw ratio.In this paper,when the pre-drafting temperature was 60℃, the ratio was 2 and the drafting temperature was 100℃,the ratio was 3, the prepared PAN fibers have excellent properties.