An Investigation of Some Environmental Factors Affecting Migration-induced Degradation in Paper
| Main Authors: | , |
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| Format: | Article |
| Language: | English Slovak |
| ISSN: | ISSN 0034-5806 |
| Online Access: | http://www.viks.sk/chk/res_92_78_94.doc |
| Abstract: | Conclusions. It should be remembered that the acidic degradation of paper, measured by changes in pH, is a fundamental but far from comprehensive analysis of the condition of any paper object. This study used comparative pH reading analysis principally because the process has been and is still being referred to as acid migration. The results from the first part of this study indicate that this form of degradation can be induced quite readily and that an increase in acidity is one of its most salient consequences. Unfortunately, the second part of this study failed to identify the volatiles. The following conclusions summarize the specific results of this study: ˙ Significant migration-induced degradation can occur within short periods of time, causing increases in the acidity of affected paper. ˙ Migration-induced degradation appears to be accelerated by increasing RH and, to a lesser extent, by increasing temperature. High RH contributed to the transport and deposition of degradative volatiles present in the chambers. ˙ Migration-induced degradation is not necessarily a contact-based phenomenon. Neutral pH paper decreased in pH to the same degree, whether it was in physical contact with the acidic newsprint or just exposed to the chamber environment where volatiles from the newsprint were present. ˙ Mylar encapsulation is an effective barrier for volatile degradation products. Although it will keep external volatiles from penetrating to attack a vulnerable paper object, it will also prevent any volatiles generated within from escaping and thereby accelerate pH decline. ˙ If samples were only partially exposed to the contaminated chamber environment there was a smaller decline in pH relative to fully exposed samples. Air flow, particularly the presence of oxygen, may play a role in the transport and/or reactivity of volatiles. ˙ Tissue interleaf buffering was only effective in inhibiting migration-induced changes in pH at high relative humidities (> 70%). However, the buffering did inhibit pH decline of the tissue itself. Unbuffered tissues had no significant effect under any conditions. ˙ The presence of volatile degradation products was not confirmed by gas chromatographic analysis of air samples. This was not a conclusive analysis, given the limitations of the method of sampling and detection (it is most effective at finding specific known impurities). No previous studies have empirically identified volatiles from degraded paper. Although environmental factors play a key role in migration-induced degradation, conclusive findings will be difficult to derive without further analysis and identification of the volatile degradation products that can be produced by paper. Summaries. The influence of selected environmental factors on the degradative process commonly referred to as acid migration was studied: the effects of heat, humidity and surface exposure on the acidity of paper specimens in contact with or in close proximity to acidic newsprint. Interleaving tissues and Mylar encapsulation were studied for their potential barrier properties. The experiments indicated a significant migration-induced degradation; it was accelerated by increasing temperature and humidity. Although encapsulation protected specimens from external volatiles, it accelerated the rate of degradation if internal volatiles were present. Buffered tissue interleaving only inhibited migration at high relative humidities, whereas unbuffered tissue was ineffective in all cases. |
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| ISSN: | ISSN 0034-5806 |
