Effects of natural ageing on the quality of cellulose polymer and the paper properties

Abstract Paper made from cellulose fibers has a life of its own and will begin to break over time due to auto-oxidation and hydrolysis. In this study we, sought to investigate the effect of natural ageing on the properties of cellulose fibres and therefore on the strength properties of paper. It has been observed that, the content of twisted fibres about 28–41% in mechanical pulp and from 27–34% in chemical pulp, which could resulted in a decrease in the strength properties of the paper. Elongation of a mechanical pulp sheets before the break was found to be increased approximately from 1.45 to 5.72%, correspondingly the tensile energy absorption (TEA) was found to be increased from 14.5 to 58.1 J/m 2 . Carbonyl groups are the intermediate or end products of cellulose degradation, which indicates the ageing of a paper. More carbonyl groups are identified in the mechanical pulp sheets with respect to chemical pulp sheets. When the paper was subjected to natural ageing the pH was increased from neutral pH-7 to 9, but the effect was acknowledged lower in mechanical pulp sheets.