Kinetic approach to degradation of paper. In situ FTIR transmission studies on hydrolysis and oxidation

This study deals with the quantitative and qualitative interpretation of transmission FTIR spectra of aged model paper samples (pure cellulose and cellulose modified with aluminium sulphate) to prepare the basis for a kinetic model of cellulose degradation involving mixed hydrolytic and oxidative mechanism. The ageing experiments were performed in situ under various conditions (pure water vapour, dried air, 100, 150oC) to discriminate between hydrolytic and oxidative paths. The focus was on the spectra between 1500-1900 cm-1, where the products of paper ageing appear in form of various carbonyl groups. A procedure of spectra standardization allowed combining the bands area with conversion of carbon atoms in cellulose upon ageing. From the time evolution of the bands the overall kinetic curves were generated and preliminarily analysed. The positions of the carbonyl bands were verified by independent experiments. Basing on these facts a mechanism assuming parallel-consecutive oxidation and autocatalytic hydrolysis was proposed.