Study On Strengthening Of Deteriorated Paper Based On Nanocellulose

Paper relics including precious ancient books,calligraphy and paintings,as well as important manuscripts,letters,archives,newspapers,etc.,have unique cultural and historical value.With the passage of time,the paper used as the carrier of information gradually deteriorates,causing these paper relics to face the danger of disappearing.Strengthening the deteriorated paper relics is a necessary measure to prolong its service life.Polymer material impregnation is one of the main methods of paper reinforcement.Compared with other synthetic and natural polymer reinforcement materials,nanocellulose has similar structure to paper fibers and has better compatibility with paper fibers as paper reinforcing agent.However,the existing research showed that the reinforcement effect was obvious only at higher concentration of nanocellulose.The high concentration of nanocellulose increases the cost of reinforcement,and the viscosity of the reinforcing agent is high and difficult to operate,and also causes excessive weight increase of the paper after reinforcement.The purpose of this study is to use nanocellulose with a lower concentration as the basic material,through compounding with other non-toxic and cheap materials,to achieve excellent reinforcement effect on deteriorated paper.Other materials in the experiment include low-carbon alcohol,polyvinyl alcohol(PVA),glutaraldehyde,etc.Xuan Paper and filter paper were used as the main experimental model papers.The mechanical strength of paper was used as the main optimization objective to study the influence of various factors on the reinforcement performance.The mechanical properties of paper were mainly measured in terms of tensile strength,number of double folds,and tearing strength.At the same time,the paper brightness,glossiness,quantitative,thickness,p H and other changes before and after strengthening were compared.The optical microscope,fiber analyzer,scanning electron microscope,powder X-ray diffractometer and Fourier transform infrared spectrum were used to characterize the appearance and microstructure of paper before and after reinforcement.The optimized reinforcement solution formulation was also used for the treatment of dry heat accelerated aging Xuan Paper,filter paper,and other paper such as printing paper,newspaper,old book paper and bamboo paper to investigate the applicability of the reinforcement solution to different papers.First,the paper treated with nanocellulose alcohol suspension was studied.The mechanical properties of Xuan Paper can be significantly improved by alcohol solution with low concentration of nanocellulose.When the paper was treated with 0.3% nanocellulose suspension containing 5% ethanol,the tensile strength of Xuan Paper increased nearly one time and number of double folds increased five times,which was much better than that of Xuan Paper treated with 0.5% nanocellulose aqueous solution.When the deteriorated Xuan Paper,which was attained by the dry heat accelerated aging at 105? for 8 days,was treated by 0.3% nanocellulose suspension containing 5% ethanol,its tensile strength can be increased by more than one time,and number of double folds can be increased by about 11 times.The mechanical properties of the strengthened Xuan Paper were significantly better than that of the original Xuan Paper without aging.The solution can also be used to reinforce bamboo paper and newspaper,and number of double folds increased by about 50% and 44%,respectively.Further,the paper was strengthened by PVA/nanocellulose composite solution.Although the mechanical strength of paper increased with the increase of PVA content when treated with PVA solution alone.But the viscosity of PVA is high when the concentration is high.When using PVA/nanocellulose composite,the lower PVA concentration and nanocellulose concentration can obtain excellent reinforcement effect.After 0.8% PVA/0.3% nanocellulose mixed solution treatment,the tensile strength of the filter paper was increased by about 50% and the number of double folds was increased by about 3.4 times.When the deteriorated Xuan Paper,which was attained by the dry heat accelerated aging at 105? for 10 days,was treated by 0.8% PVA/0.3% nanocellulose mixed solution,its tensile strength was increased by about 22% and number of double folds was increased by about twice.The mechanical properties after treatment were better than those of the unaged new filter paper.The reinforcing liquid also has a good reinforcement effect on Xuan Paper,printing paper,and old book paper.Among them,the mechanical property enhancement effect of Xuan Paper was the most obvious,the tensile strength was increased by about 64% and the number of double folds was increased by up to 11 times.Finally,the possibility of glutaraldehyde for paper reinforcement was explored.The gas-phase and liquid-phase crosslinking of glutaraldehyde and its combination with other strengthening agents were preliminary studied.The results showed that when the paper was treated with a lower concentration of 0.2% nanocellulose/0.6% PVA composite solution first,and then treated with 3% glutaraldehyde liquid-phase crosslinking treatment,the mechanical strength of the paper was further enhanced.The tensile strength of the paper was about 44% higher than that of the original untreated sample,and the number of double folds were greatly increased from 27 times of the original untreated sample to 110 times,more than three times.The mechanical properties of bamboo paper were improved most obviously after the treatment of other papers with the reinforcement solution,in which the tensile strength was increased by one time,and the number of double folds increased from 18 times to 110 times,more than five times.After the above three methods were used to treat the paper,the apparent appearance of the paper did not change significantly,the brightness and glossiness of the paper did not change significantly.Paper fiber was clear,the space was still reserved.The paper thickness was basically unchanged,and the weight gain was less than 5%.The p H of the paper also increased from weak acid or neutral to weak alkaline.The elongation of the treated paper increased obviously.It is speculated that the strengthening treatment mainly enhanced the bond strength between the paper fibers,thus improving the mechanical strength of the paper.The researched reinforcement methods have the characteristics of obvious reinforcement effect,safety,low cost and convenient operation.It has good applicability and provides a new method for the reinforcement of deteriorated paper relics.