Preparation Of Nanocellulose As Paper Strengthening Agent From Waste Newspaper

With waste newspaper as objects,the effects of deinking technology on brightness,colors,chemical compositions,fiber morphological properties,chemical compositions,pulping,and relative crytallinity were determined.Then,nanocellulose was prepared by sulfuric acid hydrolysis method with deinked pulp as raw materals,and the properties of the nanocellulose were analyzed.Finally,the obtained nanocellulose was added to the eucalyptus wood pulp,and the paper properties difference between adding chitosan and carboxymethyl were compared.The results show that:? The best deinking conditions of waste newspaper: hydrogen peroxide 10%,sodium hydroxide 5%,Sodium 10%,additives 0.25%,pulping temperature 75 °C,aging time 40 min,at this time the whiteness value can reach 70%,improved 32.5%.? The comparison results of pulp properties before and after deinking declared that ink particles had effectively removed from fiber surface.The coefficient of variation of the pulp of alcohol benzene extractives showed the largest after treated,followed by?-cellulose,Klason lignins,acid-insoluble lignin,total lignin,pentosan,and holocellulose were relatively low.The fiber length and width is not obvious changes,but the average degree of polymerization increased significantly after deinking,the crystallinity was increased slightly.? The best technological conditions of preparing nanocellulose from waste newspaper was sulfuric acid concentration 61%,hydrolysis time 60 min,reaction temperature 45 °C,the production rate of nanocellulose 34.54%.The largest influence on preparing nanocellulose is sulfuric acid concentration,and the hydrolysis temperature and time take second place by range analysis and single factor analysis of variance.Transmission electron microscopy analysis showed that the length of nanocellulose was between 300 ~ 600 nm,with the width of nanocellulose was between 10 ~ 30 nm.? The tensile index,burst index,tear index and elongation of paper was improved by increasing nanocellulose.The paper properties of adding nanocellulose at 5.5% reached maximum.Relatively to the original paper,the tensile index,burst index,tear index and elongation were increased by 32.74%,41.35%,10.95%,12.19%.? It can be seen from the TG and DTG curves,with the addition of nanocellulose,improved the thermal stability of the paper.The best thermal stability of pulp by adding.chitosan,followed by adding nanocellulose,and the thermal stability of adding carboxymethyl cellulose were relatively small.