Effect Of Cellulase Pretreatment On The Properties Of MFC Packaging Films

There are some advantages of using cellulase to prepare of microfibrillated cellulose(MFC),such as mild reaction conditions,low energy consumption,relatively simple equipment requirements and environmental protection.However,the characteristics of the cellulase not only affectedthe adsorption qualities,and the efficiency of cellulase pretreatment,but also have impact on the properties of MFC and its films.Therefore,in order to promote the high efficiency of industrial application of MFC preparation by cellulase pretreatment,the effect of cellulase components on the pretreatment process of MFC and its filmwere investigated in this study.After be prepared by D cellulase and R cellulase,the bleached eucalyptus sulpfate pulp was used by high pressure homogenizer to prepare MFC,and MFC films were prepared by casting.Firstly,the mixed cellulase(D cellulase)and endoglucanase(R cellulase)was used to pretreatment the pulp.Secondly,the pretreatment pulp was usedhigh pressure homogeneous to prepare MFC.Finally,MFC film was prepared by casting.The research include:the analysis of the cellulasecharacteristics;the analysis of the adsorption characteristics of cellulase;the preparation of MFC;analysis the performance of MFC films.Study on the cellulase properties has arrived that the optimum cellulase activity system temperature was 60?,and the pH value was 4.8.Analysis of the cellulase adsorption characteristic showed that with the increase of temperature,the adsorption rate was decreased,and the adsorption rate K2 was decreased;?G°>0,?H°<0 indicated that the reaction of D cellulase was the self heating of physical adsorption,?G°<0,?H°<0 indicated that the reaction of R cellulase was a non spontaneous physical adsorption.After adding PDADMAC that the cellulase hydrolysis to fiber adsorption rate was increased,while the adsorption rate K2 of D cellulase was increased by 17.2616,and the adsorption rate of R cellulase K2 was increased by 0.6379.After adding PDADMAC that the D cellulase was more conducive to adsorb on fiber,the equilibrium constant K value of D cellulaseis greater than the R cellulase,but R cellulasewas easier arrived adsorption equilibriumthan D cellulase;Analysis the performance of MFC films,when the pulp concentration of 10%,cellulase dosage of 10u/g,processing time of 16h,used of R cellulase to prepare MFC that the fiber yield was 1%bigger than the D cellulase,the crystallinity was 0.17%larger than the D cellulase,and the specific surface was 1.294m2/g smaller than D cellulose.The elongation of MFC film produced by R cellulase was 1.382%bigger than the film prepared by D cellulase,and tensile strength was 25.156MPa larger than D,while oxygen permeability coefficient of was 1.606cm3·cm/(cm2·s·Pa)larger than D;When the pulp concentration of 10%,cellulase dosage of 30u/g,treatment time of 16h,the fiber yield of R cellulase was 2.78%bigger than D,the crystallinity of R cellulase was 2.59%larger than D,the surface area was 2.189m2/g smaller than D.The elongation of MFC film produced by R cellulase was 0.773%larger than D,and the tensile strength was 4.735MPa smaller than D,and the oxygen permeability coefficient was 1.822cm3·cm/(cm2·s·Pa)bigger than D;When the dosage of D cellulase was 30u/g,and the content of PDADMAC was 40%,the fiber yield was increased by 0.89%,and the crystallinity was increased by 7.3%,surface area was increased by 3.314m2/g,the elongation of MFC films have been increased by 0.363%,the tensile strength increased 1.541MPa,oxygen permeability coefficient decreased 15.706cm3·cm/(cm2·s·Pa);When the dosage of R cellulase was 10u/g,the content of PDADMAC was 80%,the preparation of MFC fiber was reduced by 0.42%,the crystallinity increased by 3.73%,increased 4.548m2/g surface area,MFC film are the breaking elongation of 1.358%and tensile strength decreased 18.371 MPa,oxygen permeability coefficient 6.562cm3·cm/(cm2·s·Pa).