Thermal Accelerated Ageing Test Method Development
| Hlavní autori: | , |
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| Médium: | Článok |
| Jazyk: | angličtina slovenčina |
| ISSN: | ISSN 0034-5806 |
| On-line prístup: | http://www.viks.sk/chk/res_2_02_89_105.doc |
| Abstrakt: | SUMMARIES. A study of the thermal ageing of paper was undertaken jointly by the U.S. Library of Congress (LOC) and the Canadian Conservation Institute (CCI) as part of the ASTM/ISR Research Program on the Effects of Ageing on Printing and Writing Papers. An overview of the CCI's part of the project and the joint CCI/LOC recommendations for an accelerated ageing test are provided. Advantages and limitations of the proposed test protocol are also discussed. RESULTS AND CONCLUSIONS. Moisture Content Study When paper is placed in the ageing chamber and conditioned at different temperatures, the relative humidity must be increased as the temperature increases to maintain the same moisture content as at ambient conditions (23°C and 50% RH) The relationship between the ageing temperature and relative humidity, required to keep the initial moisture content of the paper unchanged was found to be linear and similar for both experimental papers in the studied range of ageing temperatures (65 to 90°C) (Fig. 2). This relationship was used to determine the ageing conditions used in the Arrhenius study (65°C and 65% RH, 72°C and 67% RH, 80°C and 69% RH, and, 90°C and 72% RH). Moisture equilibrium data from the literature for the moisture content of wood shows a similar relationship between temperature and relative humidity23. Arrhenius study The rate of change in chemical and physical properties of paper aged at 65, 72, 80 and 90°C was greater for papers aged as stacks than as free hung sheets and the stack rate to sheet rate ratio increased with the ageing temperature (Table 2) as shown using DP (degree of polymerization) and tear strength (Fig. 3). These rates were used to prepare Arrhenius plots for papers aged in the form of single sheets and stacks. |
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| ISSN: | ISSN 0034-5806 |
