Preparation Of Regenerated Cellulose And Its Electrorheological Properties

Electrorheological(ER)fluid is a complex fluid composed of micro-nano-sized dielectric particles dispersed in insulating oil,which can undergo a reversible liquid-solid transition under the action of an external electric field.Therefore,its rheological properties including shear stress,viscosity,and viscoelastic modulus,etc.are instantaneously adjustable.In this paper,cellulose,a natural polymer material with abundant source,is used as the dispersive phase material of electrorheological fluid.The original cellulose is dissolved in ionic liquid and then regenerated by adding a poor solvent(water or ethanol).In this paper,we studied the effects of different ionic liquids as solvents,regeneration solvent types and regeneration temperature on the crystal form and morphology of regenerated cellulose.Then the effect of the factors on its ER properties were studied.Moreover,cellulose/Mxene composite particles were prepared by adding Mxene during the regeneration process,the ER properties of which was also studied.The specific research content is as follows:(1)Two ionic liquids with different structures were used to dissolve cellulose,and water was used as regeneration solvent.RMCC-1,RMCC-2,RMCC-3 and RMCC-4 were prepared at different regeneration temperatures.The structure of regenerated cellulose is analyzed.It is found that the morphology of regenerated cellulose is mostly random blocks with microspheres on the surface.The crystal form changes from cellulose type I to cellulose type II or amorphous.Rheological tests found that the ER properties of regenerated cellulose were improved,and RMCC-3 showed relatively good performance.(2)Two ionic liquids with different structures were used to dissolve cellulose and ethanol was used as regeneration solvent.RMCC-5,RMCC-6,RMCC-7 and RMCC-8were prepared at different regeneration temperatures.The structure of the regenerated cellulose is analyzed.It is found that the morphology of the regenerated cellulose is mostly irregular and the surface is smooth.The crystal form is transformed from cellulose I type to amorphous form.Rheological tests found that the ER properties of regenerated cellulose were improved,and RMCC-5 showed relatively good performance.(3)Ionic liquid([EMIm][Ac O])was used as the solvent,the Mxene aqueous solution was the regeneration solvent.MCC/Mxene composite particles including MCC/Mxene-0.25 and MCC/Mxene-0.5 with different Mxene content were prepared.The structure analysis showed that the composite was mainly irregular blocks.Compared with general regenerated cellulose,the crystal form did not change.The rheological test found that after adding Mxene,the ER performance was improved,and MCC/Mxene-0.25 showed better performance.