Why Does Paper Turn to Yellow as It Ages ?

Why Does Paper Turn to Yellow as It Ages ? - Surely you often Seeing a collection of books that appeared yellowing, even some of the others there were holes caused by nerds. let's learn how the heck paper books turn to yellow.

As time went on, the paper changes color to yellow. It's a natural thing and not many have questioned. Actually, why the paper change color?

Mosca Conte of Universita Roma Tor Vergata in trying to uncover the reason through research. Research results published in the journal Physical Review Letters. To conduct the study, Conte using three samples that does not bleached. The paper is included in a reactor with a condition similar environmental conditions for 48 days. Conte then compare the paper with three papers with text from the 15th century. This technique allows researchers uncover what causes discoloration of the paper. Researchers said, the paper consists of 90 percent cellulose. Over time, the building blocks of plant cell walls that is oxidized. According to Conte, oxidation is able to change the composition of a variety of molecules and turn them into something called chromophores, which absorb light.

Courtesy of Conte et al.

 Conte and crew studied the light absorption properties of healthy cellulose versus that in degraded paper in order to ascertain what chemical structures are present. The two states of paper show markedly different light absorption bands, pointing to the different molecular structures present in the different paper states. By matching the observed absorption bands with calculated models, they were able to identify which hydrocarbon chains are responsible for damaging paper.

Courtesy of Conte et al., Modern P2 samples vs Ancient samples

 The products of the oxidation reaction are simply rearrangements of the hydrogen, oxygen, and carbon atoms to form different chemical bonds. By sampling manuscripts from 15th century France and Italy, Conte and his team found that cellulose from this era mostly broke down to Carbon-Hydrogen-Oxygen chains belonging to the aldehydic group. See picture. With this knowledge, it is possible to devise chemical treatments to preserve paper by preventing these degradation channels. This experiment also provided a non-destructive method of ascertaining the chemical composition of the paper samples.

Paper appears white because it reflects all the light. Old paper reflects light in a specific wavelength, which makes it look yellow. Results of this study allow stakeholders to do the paper maintains, and even whiten old text and art. - Why Does Paper Turn to Yellow as It Ages ?

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