The aging behavior of the magnesium oxide system in the paper archives

The deacidification of archival paper is an extremely important link in the repair of paper archives, which refers to the neutralization of acidic substances in the paper, at the same time, a certain amount of alkaline material (alkali reserves) is precipitated in the paper to neutralize the acid produced in the natural aging process, in order to slow down the aging speed of paper and improve the life of paper.

In recent years, the non-aqueous deacidification system using basic magnesium oxide as deacidification agent and organic solvent (perfluoroheptane, cyclohexane, isopropanol, etc.) as stabilizer has become a hot research topic both at home and abroad. At present, the research on deacidification of magnesium oxide mainly focuses on the preparation of different size of basic particles and the search for better deacidification agent stabilization system, but the research on the aging behavior after deacidification is relatively blank.

Chen Ling and Huang Xiaoxia of Renmin University of China’s School of Information and resource management have written about the aging behavior of non-aqueous MGO deacidification systems in paper archives, a series of aging behaviors of acidic writing paper files after deacidification by magnesium oxide system were systematically described from a chemical kinetics point of view, and the correctness of the kinetic theory was verified by a complete physical and chemical characterization.

At the same time, the standard UV, dry heat and hygrothermal aging tests were used to study the deacidification of the acidic writing paper used in archives after deacidification with micron-grade and nanometer-grade basic magnesium oxide deacidification solution, respectively, the change of physical and chemical properties of paper during accelerated aging process under different external conditions.

Due to the length of this section, the experimental process is omitted here. If you are interested, please refer to the author’s original article and share the experimental conclusions below:

In this paper, the author used the non-aqueous deacidification system of micron and nanometer grade magnesium oxide to deacidification experiment on the acid writing paper used in archives, the changes of physical, chemical and optical properties of deacidified paper during the aging process were analyzed by dry heat, ultraviolet and wet heat aging tests. The results of SEM and EDS showed that compared with micron-sized mgo, nano-sized mgo was smaller, better dispersed and could penetrate into the surface of paper.

After three kinds of aging, the pH value of the deacidified paper remained good, and the paper sample treated with nano-mgo had better pH aging result. The mechanical properties of the deacidified writing paper changed little in transverse and longitudinal direction after dry heat and UV aging. With the increase of hygrothermal aging time, the folding times of acid-free paper decreased exponentially, and the tensile strength remained unchanged.

The whiteness of the three groups of samples decreased significantly after UV and dry heat aging, and the difference between Colorfulness and China changed significantly (all more than 1.5) , the difference of color and whiteness of the three patterns showed a nearly linear change process (3 ~ 15 days) with the increase of hygrothermal aging time. The mechanical properties of paper were not obviously improved by two deacidification systems, but both systems could slow down the yellowing rate of paper.

In conclusion, the non-aqueous deacidification system of magnesium oxide has a good deacidification effect on the acid files on the carrier of writing paper, which can slow down the aging rate of fiber and increase the service life of acid writing paper files.

High Purity Magnesium Oxide
High Purity Magnesium Oxide

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