INVESTIGATION OF THE AGING OF BOOKS

Abstract

The book is an edition intended for long-term use and enclosed in a specially made binding. As a carrier of information, an important property of paper for documents and books is its durability. The durability of paper is its ability to retain certain physic-mechanical, optical and chemical properties unchanged over time. The durability of the paper depends primarily on its composition and the conditions of receipt and storage. Paper made from plant fibres ages over time. Paper aging depends on the type and chemical composition of the fibrous materials, sizing agents, fillers, colorants, pH of the medium, storage conditions of the paper (relative humidity and temperature), the degree of exposure of light rays to the paper and microbiological factors. For this reason, the aging resistance of fibrous materials is understood as their ability to resist the action of external and internal factors during long-term storage. The aging of the paper is accompanied by a decrease in mechanical strength and whiteness, caused by profound chemical changes in the macromolecule of cellulose - rupture of polymer chains, the emergence of new functional groups, initiating further destructive processes. Chemical reactions in aging are caused by a variety of factors. In the presence of moisture adsorbed by the air, hydrolytic destruction of the cellulose is initiated. In the aging process, oxidative processes increase the acidity of the paper. In this way, the aging of the paper is accelerated. This process is irreversible and is associated with a change in the chemical composition of the paper and a decrease in the degree of whiteness and mechanical strength. The book consists of different parts connected to each other: a book body and cover, a cover and many details. Each element of the book is exposed to external influences and ages differently. During storage, the fibrous materials and papers turn yellow and at the same time the mechanical properties decrease. This paper examines the changes that occur with the elements of the book over time. Because the process of natural aging is too long, the method of artificially accelerated aging is used to determine the tendency of paper to age. In order to follow the processes, thermal aging was carried out at temperatures of 90, 105 and 120°С. The degree of whiteness was studied as an indicator of the changes in the elements of the books. The changes with the indicator degree of whiteness after 6, 12, 18, 24, 36, 48 and 72 h of thermal aging of the different parts of a book are traced. Current research will help to clarify and control the aging process of books.