Spectroscopic studies of the ageing of cellulosic paper

Fourier transform infrared (FTIR) and near-infrared (NIR) spectroscopy have been used to characterise the ageing of cellulosic paper, with the long te rm aim of developing a technique to assess the condition of paper insulatio n in electrical transformers. There are differences in the spectra of new a nd aged materials from different sources, which provide the basis of a "fin gerprint" method to categorise papers into different "families". Measuremen ts of the rate of development of a carbonyl band during ageing in air give an activation energy of 98 kJ/mol for cellulose oxidation. Applying chemome tric methods to NIR spectra of aged cellulose gives a correlation of 0.994 between the spectra and time of ageing, with an error of prediction of 95 h for samples up to 3000 h of ageing. (C) 2001 Elsevier Science Ltd. All rig hts reserved.