Deacidification And Reinforcement Of Aged Paper Based On Nanocomposite And Its Anti-Aging Mechanism

Paper literature record the outstanding culture in the long history of mankind,which is of great significance to the dissemination and exchange of cultural information.However,due to internal and external factors such as papermaking process and storage environment,papers are acidified,making paper literature become brittle and fragile and lose the value of use.Therefore,deacidification of paper has become the primary task at present,with a purpose to delay the degradation of paper fibers and extend the service life of paper literature.In addition,increasing the strength of paper during the deacidification also requires more research.The research object of this paper is the aged books with a certain degree of acidification and aging.With Nano-zinc oxide(nano-ZnO)as deacidification agent,synthetic latex(DJ)and nano-cellulose(NFC)as strengthening agent,three types of composite conservation suspension with multifunctions as deacidification,reinforcement and hydrophobic effect were prepared.The prepared conservation suspension was coated on the aged books using screen printing.Firstly,the deacidification and enhancement effects of DJ/nano-ZnO bi-components,NFC/nano-ZnO bi-components and NFC/DJ/nano-ZnO tri-components conservation suspension on the aged paper were studied.Nano-ZnO dosage,DJ dosage,NFC dosage,screen mesh number,coating amount and other influencing factors were systematically analyzed,and the treatment process were optimized.Then the hydrophobicity of the treated paper was analyzed by measuring the surface contact angle of the paper.Finally,the aging resistance of the treated paper was explored preliminarily by comparing the changes of p H value,tensile index,tear index and burst index of paper before and after hot-humid aging and analyzing the changes of crystallinity index with XRD test.The main conclusions are as follows:As for DJ/nano-ZnO bi-components conservation suspension as deacidification and reinforcement agent,a relatively good conservation results is obtained when the nano-ZnO dosage is 6 wt%,the DJ dosage is 14 wt%,the screen mesh is 350 mesh,and the coating weight is 4.1 g/m~2.Under these treatment conditions,the treated paper presents weak alkalinity,with the p H value increased from 6.44 to 7.08.In the meanwhile,the tensile index,tear index and burst index of the paperare increased by 23.60%,11.06%and 39.84%,respectively,which shows an obvious strengthening effect of DJ/nano-ZnO bi-components.When NFC/nano-ZnO bi-components conservation suspension as deacidification and reinforcement agent,the appropriate treatment process are as follows:the nano-ZnO dosage is3 wt%,the NFC dosage is 0.55 wt%,the screen mesh is 100 mesh and the coating weight is3.4 g/m~2.Under these treatment conditions,the treated paper posses weak alkalinity,with the p H value increased from 6.28 to 7.42.In addition,the tear index and burst index of the paper are increased by 71.54%and 12.34%,which shows an obvious strengthening effect of NFC/nano-ZnO bi-components.NFC/DJ/nano-ZnO tri-components conservation suspension was used as deacidification and reinforcement agent.Detailly,the optimal working conditions of the experiment are:the nano-ZnO dosage is 3 wt%,the content of DJ dosage is 15 wt%,the NFC dosage is 0.4 wt%,the screen mesh is 100 mesh and the coating weight is 7.9 g/m~2.Under these treatment conditions,the p H value of the treated paper is increased from 6.44 to 7.14.In the meanwhile,the tensile index,tear index and burst index of the paper are increased by 23.39%,18.41%and 21.21%,respectively.The effect of nano-ZnO dosage on the surface contact angle of the paper in DJ/nano-ZnO and NFC/nano-ZnO bi-components conservation suspension were studied.The results show that:when the dosage of nano-ZnO was 14 wt%,the surface contact angle of the paper treated with DJ/nano-ZnO conservation suspension was 102.3°at 0 s,which was 33.03%higher than that(76.9°)of untreated paper,and it was decreased by 4.99%at 10 s.For the paper treated with NFC/nano-ZnO conservation suspension,when the nano-ZnO dosage was 4 wt%,the surface contact angle was 127.7°,which was 16.00%more than that(111.7°)of untreated paper,and it was decreased to 116.4°after 10 s,with a decrease of 8.85%.The increase of the surface contact angle of the paper treated by DJ/nano-ZnO conservation suspension was larger than that of paper treated by NFC/nano-ZnO bi-components,and the decreaserate of the surface contact angle of the paper treated by DJ/nano-ZnO conservation suspension was lower after the same time of infiltration with paper treated by NFC/nano-ZnO bi-components.This was because the DJ posseses water resistance,which enable paper treated by DJ/nano-ZnO to have better water resistance.By comparing the changes of p H value,physical strength(tensile strength,tear strength,burst strength)and whiteness of the paper before and after aging,combined with the XRD analysis,it was found that paper treated by all the three kinds of conservation suspension have certain aging resistance when compared to untreated paper.