| Paper cultural relics are the main carrier of the spread of human civilization,and the record and witness of human civilization.In the five thousand years of Chinese history,the paper cultural relics which record the history,culture,economy and science and technology of ancient China,have high research value.However,many paper cultural relics have suffered in crease,deformation,fracture,mildew,acidification,aging and other diseases,which have made the paper cultural relics suffered different degrees of damage,seriously affect the life of paper cultural relics.Therefore,it is urgent to protect paper cultural relics.Nanocellulose is a natural polymer material with good physical and chemical properties.As a kind of nanocellulose,bacterial cellulose has not only good mechanical properties and biocompatibility,but also high crystallinity,large specific surface area,low thermal expansion coefficient,three-dimensional multi-space structure and anisotropy.Therefore,bacterial cellulose was chosen as reinforcement agent to strengthen paper,and the bacterial cellulose combined with nano-zinc oxide to deacidify and protect paper.This study focuses on the following four aspects:1.Comparison study of three kinds of nanocellulose on the paper strengtheningThe microstructure and crystallicity of cellulose nanocrystal(CNC),cellulose nanofibers(CNF)and bacterial cellulose(BC)were studied.The results showed that the fiber length of BC was much larger than that of the other two kinds of nanocellulose,and the crystallity of bacterial cellulose was 68.29%.The hydrophilicity,thermal stability,light transmittance and mechanical properties of the three kinds of films were tested.It was found that the bacterial cellulose film has high thermal stability,good mechanical properties,and the light transmittance can reach 90%.The tensile strength,folding degree,color difference,whiteness,microscopy of samples before and after aging were analyzed.The results showed that the mechanical strength of samples treated with bacterial cellulose dispersion increased significantly and the color difference was less.2.Study on strengthening of bacterial cellulose on paperDifferent concentrations of bacterial cellulose water dispersion were uniform coated on the paper samples.The tensile strength,folding resistance,gloss,flexibility,thickness,color and pH value of samples before and after aging were tested.The results showed that the optimal concentrations of bacterial cellulose was 0.3%,the mechanical properties of the paper improve the sharpest,the transverse and longitudinal tensile strength were respectively 1.3655 kN/m and 2.6950 kN/m,the transverse and longitudinal folding resistance were respectively 20 double fold times and 28 double fold times.The softness was better,and the color difference and pH were respectively 0.41 and 6.15.The FTIR and TG of paper before and after treatment with 0.3%BC were tested and analyzed.It was found that the characteristic peaks of cellulose after treaed with bacterial cellulose was strengthened,and the thermal stability of paper was improved.The bacterial cellulose with a concentration of 0.3%was sprayed on other types of paper.The mechanical strength,pH value and color difference of the paper before and after treatment were tested.It was found that the bacterial cellulose had a strengthening effect on other types of paper,and the changes of pH value and color difference of the paper were very small.3.Study on deacidification and reinforcement of acid paper by bacterial cellulose combined with nano-zinc oxideThe nano-zinc oxide dispersed with different concentrations were evenly sprayed on the paper.The tensile strength,folding degree and color difference of paper were tested.The results showed that when the concentration of the nano-zinc oxide was higher than 1.0%.The samples' pH before and after aging was higher than 7.7.When the concentration of nano-zinc oxide was 1.0%,the color difference was 2.5,which was a tiny color change.The paper was deacidified and strengthened using the bacterial cellulose combined with nano-zinc oxide.The mechanical properties,microscopic morphology,contact angle,pH and color difference of the paper samples were performed.The results showed that the mechanical properties of the paper were significantly improved.The hydrophilicity of the paper was maintained.The microstructure of bacterial cellulose combined with nano-zinc oxide was analysed with SEM,XPS and FTIR,and the thermal stability was characterized by TG.It was found that the composite of bacterial cellulose and nano-zinc oxide had better stability,and the interaction between nano-zinc oxide and bacterial cellulose improved the thermal stability of bacterial cellulose,thereby achieving the purpose of improving the performance of paper.4.Study on antifungal activity of bacterial cellulose combined with nano-zinc oxide on paperThe fungi can produce several types of damages,such as colored spots,discoloration of pigments and changes in the chemical and physical properties of paper.In order to investigate the antifungal effect of bacterial cellulose combined with nano-sized zinc oxide on paper,four kinds of common moulds of paper were inoculated into media.Different substances were added into the media to simulate different environments.The growth of molds in a certain period of time was observed and recorded.It was found that aspergillus niger,aspergillus flavus,penicillium and aspergillus fumigatus grew at different rates.After 7 days,the growth areas of moulds in bacterial cellulose media were respectively 100,90,90,75 and in BZ media were respectively 2,2,1.5,0.After 7 days,the growth areas of moulds covered by BC membrane reached more than 90%,while the growth areas of moulds covered by BZ membrane was 0.The paper before and after treatment was put into the inoculated medium.It was found that the mold on the paper after treated with treatment was effectively suppressed,indicating that the compound of bacterial cellulose and nano zinc oxide had a better inhibition effect to the mold. |
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