Answer to Question #62356 in General Chemistry for Vikash Soni

Question

Sir, why pages of old books turn yellow with time ?
And is there any method to prevent yellowing of pages?
And now-a-days , is there any advance manufacturing process for books by which this yellowing can be stopped ..

Answer 1

The basis of the paper cellulose but the material is not chemically pure. Natural whiteness wood cellulose is noticeably inferior to white cotton paper. To remove a paper yellowness mineral fillers and chemically bleached fiber are added. When the obtained whiteness degree is not sufficient, then the surface is subjected to chalking process. In this case, the exclusive surface coated with inorganic layer, increased degree of whiteness.
Since the white color of the paper is achieved through a series of complex processes, the yellowing can occur for many reasons.
1) Light. Especially harmful direct sunlight. Ultraviolet radiation, through which we get a sun sunburn, stimulates the disintegration of cellulose polymer molecules.
2) Heat. Heat again stimulates the decomposition reaction. Furthermore, uneven heating contributes to the filler particles shattering.
3) A mechanical bending. This destroys chalk overlay surface and crumble the filler particles.