Research On The Protection Of Paper Cultural Relics By Nano-chitosan

At present,the oldest known archaeological fragments to modern paper date to the 105 A.D.in China.The pulp papermaking process is ascribed to Cai Lun,a 2nd-century CE Han court eunuch,which is a revolution of writing materials.Since then,paper turns into the main carrier material of archives and information records.Existing ancient books are even voluminous.Under the rapid development of science and technology,new carrier materials are constantly emerged.Although the application effect of paper in the environment is not good enough,the emergence of these carrier materials have not wavered the dominance of paper by other materials in the archives.A great deal of data show that some diseases like acidification,rot,mildew and so forth caused by paper itself,the preservation of environment and other factors brought about many serious consequences,resulting in self-destruction among a large number of precious cultural relics,paper archives and books.Therefore,protective measures are needed urgently.Nowadays,there are amounts of protective methods including deacidification and reinforcement.Notwithstanding effectivity among many methods,few methods can play the role of deacidification,strengthening and antifungal at the same time,and these protective materials could similar to paper structure.Based on it,three aspects of research work were performed in the thesis.And it is expected to provide a new economical and effective method for the conservation of paper relics.Therefore,this thesis focuses on the following aspects:1.Preparation and characterization of chitosan nanoparticalsChitosan nanoparticles were prepared by two methods,chemical crosslinking and physical milling.The micromorphology and physicochemical properties of chitosan nanoparticles were observed by SEM,AFM,FTIR,XRD and Gel Permeation Chromatograph.According to these experimental results,both of the two methods can obtain nanometer level chitosan.The size of chitosan particles prepared by crosslinking method were more uniform,but the yield is relatively low and cannot meet the needs of applications on the paper.The chitosan nanoparticles prepared by ball milling method were not uniform,but there were a considerable part of the samples conform to nanometer size.Besides,the yield of nanosized chitosan was higher than the chemical methods.The molecular weight decreased after ball milling,but molecular structure was not changed.So,this method is the ideal preparation way of chitosan nanoparticles.2.Study on deacidification and strengthening of acidic paperTwo kinds of ShuXuan paper were treated by spraying the dispersion of chitosan nanoparticles-isopropanol and the dispersion of Ca(OH)2 nanoparticles-isopropanol separately.The acidity and mechanical strength of the paper samples were tested.The results show that chitosan nanoparticles is effective to neutralize the acid in the samples,and improve the samples' mechanical strength significantly.The paper samples pH and mechanical strength were tested before and after artificial aging.The results show that samples treated by chitosan nanoparticles were more durable than the samples treated with Ca(OH)2 nanoparticles and the untreated samples.The surface morphology,structure and chemical state of N and O elements of samples before and treated with chitosan nanoparticles were analyzed by SEM,infrared spectroscopy and multi-function imaging photoelectron spectroscopy.The results show that a piece of thin film was formed on the surface of the treated paper.The N element binding energy of chitosan was changed significantly,which is also the main mechanism of chitosan deacidification.3.Study on the mildew inhibitory effect of chitosan nanoparticles on paperThe degradation of mildew is not conducive to the long-term preservation of paper,especially the breeding of mildew on paper.Mycelium is a type of destructive things to the written paper,and its metabolic growth is one of the important factors,which affect the preservation of paper.In order to study the anti-fungal effect of chitosan nanoparticles on paper,this part of the experiment is as follows.?The mycete was collected and cultured from the mildew growth of books or archives;?Different kinds of mildew were separated and purified;?The growth of mildew in the medium was observed,and the contrast experiments were designed according to simulating different environment;?The mycotic spores were inoculated on paper and the growth of mildew was observed after a period of time.The effect of chitosan nanoparticles and other protectant of anti-bacteria were observed and recorded through comparison experiments.The results show that chitosan nanoparticles could effectively inhibit the growth of fungi on acid paper,and the calcium hydroxide doesn't work.4.Study on the conservation of paper with acid ink by chitosan nanoparticlesThis thesis studied the corrosion of acid ink and the conservation effect of chitosan nanoparticles for the paper.The paper samples with handwriting of blue-black ink and blue ink were aged at different environment.The results show that the strokes of handwriting parts were damaged in different degrees and the handwriting had a significantly discoloration.While the handwriting treated with chitosan nanoparticles kept well,the paper was not damaged and the color of handwriting was changed slightly.The durability of paper samples treated with nanochitosan has been significantly improved according to the mechanical strength results of samples before and after aging.So,chitosan nanoparticles play a positive role in the durable storage of these archives.