Effect of Different Pretreatments on Solubility of Hemp Fibers in Ionic Liquids

Hemp fibers were treated with different pretreatments before being put into ionic liquid dissolved systems. NaOH,HCI,N,N-dimethylacetamide( DMAc) solution and ultrasonic were utilized to activate fibers. Scanning electron microscopy( SEM),Fourier transform infrared spectroscopy( FTIR) and X-ray diffraction( XRD) were used to analyze the morphological and molecular structures of the fiber before and after activation for the comparative analysis. The pretreated fibers were dissolved and the dissolving process of fibers were observed until they were dissolved completely. Experimental studies found that NaOH solution made fibers crystal form change from cellulose Ⅰ to cellulose Ⅱ,and others didn't have this kind of change. By comparison,fibers treated by DMAc solution worked best, various methods which affected solubility could be sorted roughly as follows: DMAc ultrasonic HCI NaOH untreated.