Prediction of paper permanence by accelerated aging Kinetic analysis of the aging process
| Main Authors: | , , |
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| Format: | Article |
| Language: | English Slovak |
| ISSN: | ISSN 0969-0239 |
| Online Access: | http://www.viks.sk/chk/Cel_3_96_243_267.doc |
| Abstract: | Conclusions. Analysis of the kinetics of cellulose degradation process in aging leads to the following conclusions: (1) The kinetics of cellulose degradation in aging is described by a general kinetic model. (2) Mathematical analysis and experimental results convincingly support the applicability of the Arrhenius equation to the case of paper aging and hence extrapolation to lower temperatures. (3) Similar activation energies (104-113 kJmol-1) are found for the cellulose degradation of three bleached chemical pulps. (4) A general relationship describes the dependence of degradation rate on the moisture content and acidity of paper. The relative contribution of each parameter and their interactions are thus quantified. (5) Kinetic analysis provides further solid evidence to support acid-catalysed hydrolysis as the major aging mechanism. (6) The estimated life expectancy of paper based on the cellulose degradation kinetics depends strongly on storage conditions. Therefore, lowering both temperature and relative humidity in storage rooms (as low as practically allowed) will significantly slow down paper degradation. Summaries. The validity of accelerated aging tests to predict and rank papers on their permanence has been under question, preventing the development of performance-based standards for permanent paper. We conducted a general kinetic analysis to investigate the aging process of paper. A general kinetic model is proposed to describe the de-polymerization of cellulose. Experimentally it was shown that in the case of aging, cellulose degradation follows classic first-order kinetics as a special case of our general kinetic model. The Arrhenius equation was critically re-examined for the case of a multiple reaction system. It was shown analytically that the Arrhenius equation is still applicable when certain conditions are met. This was convincingly supported by experimental results. We also analysed the dependence of the degradation rate on the moisture content and hydrogen ion concentration. By conducting systematic experiments on these two factors, a general and quantitative relationship was established to explain the contribution of each factor and their interactions. Finally, based on this kinetic analysis, the effects of storage conditions on the life expectancy of paper were estimated. |
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| ISSN: | ISSN 0969-0239 |
