Abstract
The control of relative humidity is generally recognized as an important consideration in the proper storage and display of paper materials. However, the amount that the humidity can fluctuate and the rate at which it can change without causing damage are still unknown. In this study, samples of cotton filter paper (Whatman No. 42) were held at room temperature in a chamber having a relative humidity that alternated between 25 and 75% every two hours. Papers were removed from this chamber at intervals and analyzed for chemical deterioration, discoloration and strength loss. After roughly 2200 humidity cycles, the paper had suffered a reduction in cellulose degree of polymerization to one-half its initial value, nearly its leveling-off DP, and its zero-span tensile strength had fallen to one-third the initial fiber strength. Chemical products were found to be consistent with a predominantly hydrolytic degradation. These results, and the course of the strength loss during degradation, suggest that the cycling humidity causes rapid stress-induced hydrolysis in this filter paper.
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