Study On The Preparation Of MFC And Its Film Properties For Packaging

The energy shortage,shortage of resources and environmental pollution have become the key problems to restrict the sustainable development of the world economy.People pay more and more attention to how to reduce energy consumption,reasonable utilization of non renewable resources,efficient use of renewable resources and reduce environmental pollution.Therefore,lots of scientific research workers focus on how to use renewable resources to develop one green packaging material that keeps high qualities of plastics and enable to be degraded.Microfibrillated cellulose(MFC)was prepard from bleached eucalyptus sulpfate pulp by high pressure after cellulase processing,MFC film was made by casting method.Firstly,based on the analysis of enzymology properties,the influence of temperature and the pH value on the cellulase activity can be inspected,then the properest temperature and pH value for enzyme activity have found,which is beneficial for subsequent researching of cellulose enzyme adsorption characteristic and the preparation of microfibrillated cellulose(MFC).Secondly,this project focuses on the research of cellulase adsorption properties.By isothermal adsorption experiment,adsorption mechanism of cellulase to cellulose was analyzed.The add effect of poly two methyl ammonium chloride(PDADMAC)on the adsorption characteristics of Cellulase was investigate.Thirdly,it was mainly about the preparation of MFC by cellulase pretreatment:Single factor analysis was made on the effect of pulp concentration,enzyme dosage,treatment time on MFC performance and film packaging performance.Finally,the response surface methodology was used to optimize and analyze the process conditions,which were the MFC diameter,specific surface area and the tensile strength of MFC films.According to the properties of enzyme,The optimum enzyme activity temperature was 55℃,and the pH value was 4.8.Isothermal adsorption experiments of cellulase on the fibre surface showed that cellulase was adsorbed on quickly the fiber surface at the beginning of the adsorption(within 10min)and the adsorption achieveed a balance after 60 minutes.The protein adsorption rate increased with the concentration of pulp,With the increase of the amount of cellulase,the protein adsorption increased at first and then decreased.After adding the PDADMAC,the adsorption parameters alpha value increased from 0.917 to 0.957,fiber adsorption of cellulase adsorption parameters m values increased from 1079.9mg/g to 1084.6mg/g,and cellulase adsorption rate also increased.Is was showed that the addition of PDADMAC was benifit for the adsorption between cellulase and cellulose.Single factor experiment showed that,the suitable conditions of cellulase pretreatment for MFC preparation was as follows:pulp concentration was 10%,the amount of enzyme was 10u/g,processing time was 16h.When the amount of PDADMAC was 100%,the crystallinity of MFC increased 12%,the particle size was reduced 11%,the specific surface area was increased by nearly 42%,charge was declined 25%,the tensile strength of the MFC films increased 45%,oxygen permeability coefficient decreased by 46%,the performance of MFC and MFC films were improved obviously.Through the optimization of data by RSM，the MFC particle size and the specific surface area were the response value,the optimal conditions of cellulase pretreatment for the preparation of MFC were:pulp concentration was 10%,cellulase dosage was 10.53u/g,processing time was 24h.When the tensile strength of MFC thin film was used as the response value,the optimum conditions for the preparation of MFC by cellulase treatment were as follows:the concentration of pulp was 10%,the amount of cellulase was 11.74u/g,the treatment time was 24h.