Study On The Mechanism Of Anti-scouring Effect Of Alum On Paper

Xuan paper has a long history and artist use it to inherit arts and humanities.However,the artists' painting were so easy to be blurry and fade as time goes by that recovery technique appear,which including washing,showing up,repairing and coloring.In the recovery processing,gelatin and alum were used before coloring,because of its water-resistance.The gelatin and alum stemmed from Tang Dynasty were the fundamental material of painting technology,cultural relic repairing and traditional Chinese painting creation and mounting.To our disappoint,there is no concrete study on gelatin and alum,resistance to water.Only lots of study on the physical performance index of paper treated with gelatin and alum.In fact,there exist a sort of sizing agents besides gelatin and alum,and people classified them as nature and man-made sizing.The mechanism of man-made sizing is clear due to its structure of long hydrophobic chains.By contrast,the nature sizing agent has the extraordinary complex structure,and it is difficult to analysis the relationship between the structure and water-resistance properties.Though research indicate that the nature sizing water-resistance properties are related to their structure,there still lack specific and micro theory to explain the water-resistance phenomenon.For this reason,we project a serious of experiment to interpretation why gelatin and alum could prevent water spread.In addition,Xuan paper' s pore led to its property of absorbing water.In order to research in all side,we also explore the gelatin and alum effect on the pore structure.In all,the main work in this thesis were as follows:(1)The effect of gelatin and alum on the paper fiber structureXuan paper is mainly composed of fibra which arranging in order and entangling with each other,xuan paper is a porousous network structure which water easily penetrate in.XRD showed when alum solution is separately dripped on the surface of xuan paper,the aluminum ion combined with the glycoside bond oxygen as a catalyst that catalyzes the acid alum solution to hydrolyze the paper cellulose thus decreases paper's crystallinity.while gelatin?alum are adding together,the crystal structure of paper fiber basically remain the same.it means gelatin and fiber combine with Al3+ are competitive.Gelatin replaces hydroxide radical on fiber reacts with Al3+ somehow eases the influence of Al3+ on paper.SEM observation showed that gelatin and alum increases the density of paper fiber density?smooth the paper surface?decreases Single fiber bundle Capillary effect caused by cracks are helpful avoiding water penetration.The BET and mercury intrusion tests showed that the alum water obviously filled the pores of the Sheng Xuan and prevented the carbon particles in the ink from diffusing,also avoided the occurrence of water penetration.(2)The interaction of gelatin and alum in solutionIn this part,the effects of alum on gelatin solution viscosity,pH,particle size,fluorescence properties and gelatin surface composition were investigated;the interaction between alum and gelatin was studied.The results showed that alum reduces the pH of gelatin solution and increases the viscosity and particle size of gelatin solution.The fluorescence intensity of gelatin decreased with the decrease of pH,and the addition of alum increased the weakening of gelatin fluorescence,indicating that the combination of alum and gelatin promoted fluorescence quenching.The circular dichroic test showed that the gelatin-alum solution showed more ?-sheet structure.(3)The distribution of hydrophobic groups on the surface of the gelatin-alum changing during drying.This part invested the changes of hydrophobicity in the surface of different drying processes.Freeze-dried Sheng Xuan did not avoid water penetrate,while naturally dried Sheng Xuan surface was hydrophobic,avoided the occurrence of water penetration.By detecting the surface elements of Sheng Xuan and tracking of Al and N elements in different drying layers,it is found that the Al element moves from the surface to the inside during the drying process,on the contrary,the N element distribution gradually Increased from the inside to the outside,confirmed that gelatin peptide chain conformational changes in the process of drying process.The results of fluorescence test of sizing agent under different drying conditions showed that alum causes the hydrophobic molecular conformation of gelatin changed,caused the hydrophobic amino acid arranged outwardly,thus enhancing the hydrophobicity of the paper surface.The ATR-FTIR and Raman test fatherly proved that the hydrophilic groups on the gelatin surface decreased.In a word,the alum changed gelatin conformation to reversal,reduced the number the hydrophilic groups on the surface of gelatin-alum film,enhanced its hydrophobicity,and improved its anti-water penetration effect.