Study On The Application Of Cellulose Derivatives On The Reinforcement Of Aged Newspaper

Paper as carrier of written information recorded our history and culture,which have precious value on humanities and art.With the passage of time,aged phenomenon,such as acidification,yellowing,brittle,appeared on the mostly aged paper,which result in the reduction of mechanical strength and damaging during browsing and use.To effectively extend the life of paper,improving mechanical strength of paper and deacidification are two important means.This thesis focuses on the applications of cellulose derivatives on reinforcement of aged paper,in other words,finding an efficient method to improve the mechanical strength of paper and remove the acid in paper.Moreover,the method should preserve the content readable on aged paper.Existing research results indicate that cellulose materials,such as Nano-cellulose,have proven properties to improve the mechanical strength of paper,and sodium tetraborate has well-known application on deacidification of aged paper.Therefore,four kinds of cellulose derivatives and sodium tetraborate were selected as reinforcing and deacidification materials.1,4-bis(triethoxymethoxysilane)benzene(BTEB)was used as auxiliary before reinforcement of aged paper.In order to protect the water-soluble ink handwriting on aged paper,a mixture of water and ethanol was used as the solvent.This study is proceeded by these following steps:(1)According to the effect of reinforcing agent on mechanical strength of paper,mechanical strength test was applied to these four cellulose derivatives,sodium carboxymethyl cellulose(CMC-Na),calcium carboxymethyl cellulose(CMC-Ca),cationic guar gum(CGG),and cationic starch to select a suitable reinforcement agent,.The mechanical strength test data shows that CMC-Na has better reinforcing effect comparing to other testing materials.With 1% concentration of CMC-Na,the folding resistance of aged paper was increased by 10 times,the tearing strength was increased by 50%,and the tensile strength was increased by 95.5%.With the pretreatment of BTEB,the strengthening effect of the reinforcing agent was increased by 10% than the baseline.The chromatism of black,red and blue ink dyed paper samples before and after reinforcement is 0.6,3.9 and 6.5 respectively.After reinforcement,the pH value of the aged paper increased from 3.48 to 5.09.Therefore,CMC-Na was selected as reinforcing agent in the following experiment.(2)Aiming at increasing solvability of CMC-Na and lower water content in reinforcing agent,the following optimization were performed on the agent:Propylene triol has a large amount of hydroxide,can play a role in solubility,but propylene triol will increase the viscosity of reinforcement.Experiment found that reinforcing agent with higher viscosity shows less reinforcing effect on aged paper.Thus,the optimized mass ratio of ethanol and glycerol was set to be 6:1.The aqueous solution of sodium tetraborate with a concentration of 0.5% was used to replace the original aqueous solvent to improve the deacidification ability of reinforcing agent.Under 1.0% concentration of cellulose derivatives,the minimum moisture content in reinforcing agent could be reduced from 50% to 40%.After optimization,the CMC-Na reinforcing agent can increase the pH value on aged paper surface to 8.5 while maintain the reinforcing effect on aged paper,moreover,reduce the chromatism of the blue ink dyed paper.(3)To explore the existence form of reinforcing agent in the aged paper and reinforcing mechanism,dying standardization was applied to reinforcing agent and aged paper.During pre-preparation,direct red was used to dye aged paper,fluorescent green sodium salt was grafted to the sodium carboxymethyl cellulose sodium to produce fluorescent green dye what would be used to dye reinforcing agent.Dyed reinforcing agent was employed on direct red dyed aged paper in the reinforcement.The penetration process of reinforcing agent within aged paper was discovered with confocal atomic microscope(Confocal).The confocal observation shows that majority of reinforcing agent was able to penetrate into aged paper,small portion of agent remain on the paper surface.The reinforcing mechanism of reinforcing agent on the mechanical strength of aged paper was explored by combining the characterization results,the change of mechanical and other physical properties of aged paper before and after treatment.After comprehensive analysis,It can be inferred that the reinforcement mechanism of reinforcing agent may be that reinforcing agent penetrates deeply into the microstructure of paper,fulfills the gap between the fibers,and then improves the density of the paper;sodium carboxymethyl cellulose provides a lot of hydroxide which increase the force of hydrogen bond between the paper fiber,thereby improves the binding force between the fiber.The reinforcing agent developed in this paper can enhance the mechanical strength of aging paper while deacidify the acid in the aging paper.This method can provide important reference value for the research and development of aging paper reinforcement agent and the strengthening and deacidification protection of paper archives in the future.