Enhancement Mechanism Of Paper Strengthening Agent Prepared From Corncob

Aiming at the problem of decreasing strength of recycled paper,this study started from the point of view of developing new high-efficiency paper strengthening agent.In the present study agricultural waste-corncobs were selected as raw materials.They were ground into powders and treated with sodium chlorite to remove lignin to generate holocellulose.And the obtained holoccllulose was modified by carboxymethylation,2,2,6,6-tetramethylpiperidine-1-oxyl(TEMPO)oxidation,and cationization,respectively.The influences of modified corncob holocellulose on the physical properties of paper and recycled paper were studied.The structures of the samples were characterized by elemental analyzer,Fourier transform infrared spectroscopy,scanning electron microscopy,atomic force microscopy,X-ray diffractometer,specific surface and porosity analyzer,and X-ray photoelectron spectroscopy,which illuminated the enhancement mechanism of modified corncob on paper.The results broadened a new way for application of corncob.The results indicated that the paper properties can be improved with addition of carboxymiethyl corncob holocellulose.Compared with the control paper,when the carboxymethylated time was 140 min,the tensile index,burst index,and folding endurance of paper with 1%carboxymethyl holocellulose were increased by 46.4%,34.2%,and 397.8%,respectively.Carboxymethyl corncob holocellulose can also improve the physical properties of recycled paper.Compared with the control recycled paper,when the carboxymethylated time was 120 min,the tensile index,burst index,and folding endurance of paper with 1%carboymethyl holocellulose were increased by 37.4%,26.3%,and 260.0%,respectively.The results indicated that adding the binary system of CMH(carboxymcthyl holocellulose)and PAE can improve the physical properties of paper when 0.6%CMH and 0.6%PAE were used,its dry tensile index and burst index were increased by 17.3%and 4.6%,respectively,compared with the paper sample with only 1.2%CMH added,when 0.6%CMH and 0.6%PAE were used,its dry tensile index and burst index were increased by 9.7%and 1.8%,respectively,compared with the paper sample with only 1.2%PAE added.Adding the binary system of CMH and CS(cationic starch)can also improve the physical properties of paper:when 0.6%CMH and 0.6%CS were used,its folding endurance was increased by 216.3%,respectively,compared with the paper sanple with only 1.2%CMH added.when 0.6%CMH and 0.6%CS were used,its dry tensile index,burst index,and folding endurance were increased by 6.6%,2.5%and 350.6%,respectively,compared with the paper sample with only 1.2%CS added.The results indicated that the oxidized corncob holocellulose can be used as a paper strength additive to improve the paper properties.Compared with the control paper,when 1%oxidized holocellulose(the oxidized time was 70 minutes and dosage of TEMPO was 0.5%)was used,the tensile index,burst index,and folding endurance were increased by 4.2%,8.6%,and 50.7%,respectively.The oxidized corncob holocellulose was also found to have the ability to improve the properties of recycled paper.Compared with the control paper,when 1%oxidized holocellulose(the oxidized time was 70 minutes and dosage of TEMPO was 0.5%)was used,the tensile index,burst index,and folding endurance of recycled paper were increased by 10.4%,19.1%,and 30.8%,respectively.The results indicated that the tensile index,brust index,and folding endurance of paper can be improved with the addition of cationic corncob holocellulose.Wlien the other conditions were certain,as the dosage of cationic agent or the cationic reaction temperature increased,the above-mentioned index values tended to first increase and then decrease.Compared with the control paper,the tensile index,brust index,and folding endurance of paper with 1%cationic holocellulose were increased by 7.2%,13.7%,and 56.0%,respectively,when the dosage of cationic agent was 25%and the cationic reaction temperature was 70?.Cationic corncob holocellulose can also improve the physical properties of recycled paper.Compared with the control recycled paper,the tensile index and folding endurance were increased by 9,2%and 30.4%,respectively,when 1%cationic holocellulose(the cationic agent was 25%and the cationic reaction temperature was 70?)was used.The results indicated that the physical strength of recycled paper,especially the tightness and tensile strength,were increased after mechanical dissociation.The carboxyl content and water retention value of the recycled fiber were increased after mechanical dissociation.Based on the above research,it can be concluded that the enhancement mechanism of modified corncob holocellulose on paper may have two kinds:one is that the modified corncob holocellulose can form hydrogen bonds or ionic bonds with pulp fiber when added into the pulp,and the other is that the modified holocellulose added can get into the pores of the fibers to improve hornification degree of fibers.