Study On The Deacidification And Reinforcement Of Paper Cultural Relics Based On Ethylene Oxid

Ancient books,paper archives,ancient calligraphy and paintings are easy to be broken in the long-term preservation process,which greatly shorten their service lifespan,which has become a great challenge for the storage of paper cultural relics,and the acidification of paper is the main factor leading to their damage.The main component of paper is cellulose.Acidification can lead to cellulose hydrolysis and embrittlement.The task of deacidification of paper cultural relics at domestic and foreign studies is still urgent.At present,the liquid-phase and gas-phase deacidification as the important techniques play a positive effect,but they are not suitable for various deacidification and large-scale treatment,and the penetration also has no desired ideal result.The author’s historical and cultural heritage protection engineering research center of Shaanxi Normal University first proposed the"binding acid"deacidification method by vapor deposition of ethylene oxide argon gas phase system in acid pape r,and created the innovative technology of gas phase,whole roll,large-scale deacidification and reinforcement,which has obtained remarkable achievements in engineering application,but its deacidification mechanism is not very clear.In order to clarify the deacidification mechanism of ethylene oxide,this paper takes the interaction between several typical organic acids that can cause paper acidification and nano cellulose as the research model,it is expected to reveal the molecular mechanism of deacidification of ethylene oxide and the mechanism of auxiliary reinforcement of paper fibers,and try to analyze the reason why the argon gas phase system shows much better deacidification effect than nitrogen gas phase system.Focusing on the above research objectives,this paper studies from the following three aspects,and obtains the corresponding results and conclusions.Firstly,taking the typical organic acid p-hydroxybenzoic acid contained in paper acidification as an example,the interaction between ethylene oxide and paper fiber adsorbed with aromatic organic acids was studied,and the deacidification of ethylene oxide and the reinforcement mechanism of paper fiber were revealed.In the first place,the reaction products of nano cellulose supported p-hydroxybenzoic acid and p-hydroxybenzoic acid solution with ethylene oxide at room temperature were characterized by ¹H NMR,¹³CNMR and IR.The results show that ethylene oxide mainly reacts with the carboxyl group in p-hydroxybenzoic acid to form ethylene glycol p-hydroxybenzoate,and reacts with water to form ethylene glycol and polycondensate.In the second place,the freeze-dried samples after the reaction of ethylene oxide with wetted nano cellulose and its reaction with p-hydroxybenzoic acid were studied.The corresponding products were characterized by FTIR and scanning electron microscope（SEM）.The results show that ethylene oxide can react not only with p-hydroxybenzoic acid solution,but also with hydroxyl groups in cellulose.With the increase of ethylene oxide,a layer of colloidal coating will appear on the surface of cellulose.The results of ¹HNMR and ¹³CNMR showed that the product contained ethylene glycol p-hydroxybenzoate,ethylene glycol and diethylene glycol.It is proved that ethylene oxide will not crosslink p-hydroxybenzoic acid on cellulose,but form free ethylene glycol p-hydroxybenzoate.The FTIR and SEM characterization results of the extracted residue showed that the reaction product of ethylene oxide and nano cellulose could not be washed away by acetone,and with the increase of the amount of ethylene oxide,the product filled the pores between fibers more obviously,indicating that ethylene oxide could react with hydroxyl groups on the surface of cellulose and form polyethylene glycol on the surface of cellulose.In the end,the deacidification and reinforcement of simulated acidified paper by ethylene oxide were studied.The pH,maximum tensile strength and folding resistance of the simulated sample before and after deacidification with ethylene oxide were detected by pH meter.The results showed that the pH and mechanical properties of the simulated paper treated with ethylene oxide were significantly improved.It shows that ethylene oxide not only has deacidification effect on paper,but also has a certain reinforcement effect.The above similar conclusions were also obtained by using hydroxycinnamic acid,vanillic acid,syringic acid and other organic acids in paper degradation instead of hydroxybenzoic acid for similar deacidification treatment.The second work revealed the interaction of ethylene oxide with alkyl-containing and substituted organic acids,acidified cellulose and paper.Taking the typical alkyl containing and substituted organic acids,nano cellulose and paper degraded and decomposed by paper as the research object,the related products were characterized by ¹HNMR,¹³CNMR,FTIR,SEM,pH meter,universal material testing machine,computer-controlled folding tester and other characterization means similar to the above-mentioned study on the interaction between p-hydroxybenzoic acid and ethylene oxide,cellulose and paper.The results show that ethylene oxide can react with these organic acids to form ethylene glycol esters of corresponding acids,showing deacidification characteristics.That is,ethylene oxide has the universality of removing organic acids.And this effect is suitable for the paper containing organic acid,which increases the pH of the acid paper.At the same time,it shows the reinforcing effect with the paper due to the self condensation of ethylene oxide to form polyethylene glycol.In particular,the free ester formed is easy to escape from the paper under the action of vacuum.The third work revealed the difference of the influence of argon and nitrogen as the dilution medium of ethylene oxide on the deacidification energy and its mechanism.After freeze-drying,the filter paper impregnated with organic acid was placed in the deacidification tank containing ethylene oxide in argon and nitrogen respectively,and the pH and bet micropore of the obtained product were tested and analyzed.The results show that the micropores of the filter paper treated with ethylene oxide argon almost completely disappear,while there are still some micropores in the filter paper treated with ethylene oxide nitrogen.The pH of the former paper increased significantly than the latter.This result suggests that in argon medium,ethylene oxide is easier to enter the pores of cellulose and interact with cellulose and its organic acids,so as to form more polyethylene glycol in the pores of paper fibers and interact with organic acids more easily.That is,argon has stronger diffusion effect of carrying ethylene oxide in paper fibers than nitrogen.Argon has stronger diffusion effect of carrying ethylene oxide in paper fibers than nitrogen,which is also confirmed by fluorescence spectroscopy.The filter paper was impregnated with p-hydroxybenzoic acid solution and then treated in ethylene oxide argon and nitrogen deacidification tank.The fluorescence spectra of hydroxybenzoic acid and ethylene glycol hydroxybenzoate were detected.The results showed that there were significant differences in fluorescence spectra before and after deacidification treatment in two atmospheres.The fluorescence intensity of deacidification product of deacidification treatment sample in argon atmosphere is stronger than that in nitrogen atmosphere.These results suggest that it is easier for ethylene oxide to interact with organic acids contained in paper in argon atmosphere.This is consistent with the conclusion of the difference of the diffusion effect of the two gases on ethylene oxide.In order to prove that the inert gas argon has more diffusion ability than nitrogen in paper fiber,the difference experiment of nitrobenzene on the fluorescence quenching effect of adsorbed fluorescent probe sodium pyrene sulfonate paper under two carrier gases was designed.The results show that the fluorescence quenching of paper fluorescent probe sodium pyrene sulfonate by fluorescence quenching agent under argon carrier gas is slightly stronger than that under nitrogen carrier gas.The results show that argon as carrier gas is easier to diffuse the quencher in the paper fiber than nitrogen.This paper reveals the deacidification of ethylene oxide gas-phase paper and the mechanism of strengthening paper at the molecular level,and explains the root of the difference between the deacidification carrier gas argon and nitrogen on the deacidification of ethylene oxide gas-phase paper.These research results have important theoretical value for deepening the deacidification effect of ethylene oxide gas-phase paper and its reinforcement effect on paper,and have important application value for optimizing the deacidification process of ethylene oxide gas-phase paper.