Improving the accuracy of estimating paper permanence for accelerated degradation in closed vials

Abstract

To more accurately predict the permanence of paper during natural aging, we studied cellulose aging according to closed vial setup, which compared to alternative paper aging methods is closer to natural aging with regard to predictions of paper life expectancy. To improve kinetic evaluation, not only cellulose degradation by hydrolysis and oxidation, but also the moisture content in the closed vial were measured during the aging process. This allowed to eliminate the long-known errors of the method caused by vial leakage which falsely produce different aging rates for different aging periods. With the aim of predicting paper permanence more accurately, several ways of considering the moisture changes and the influences of paper moisture and vial leakage were considered and an improved protocol was elaborated that corrects the rate of cellulose chain scission based on the average moisture content in the paper. Based on this hydrolysis rate, the expected half-life DP becomes independent of the aging period and thus less error-prone and more reliable. We hope that this improvement of the very common closed-vial aging method will quickly be accepted and welcomed by the paper conservation community.

The Effect of Synthetic Polymer Foams on Cellulosic Material Degradation

“…Whatman paper is 100% pulp, a material susceptible to oxidation and hydrolysis at increased temperature and humidity, manifested by a decrease in the degree of substitution and the release of furan derivatives and organic acids [ 31 , 35 , 36 , 37 ]. A considerable change of color, caused, above all, by yellowing, was recorded after separate aging of the Whatman paper.…”

“…The lowest pH of a cold extract in the sample from the white foam sandwich may be caused by the absorption of acids released from the white foam by the paper or by a greater extent of paper degradation caused by the effect of a higher concentration of acidic substances [ 37 ]. In the presence of moisture, an acidic environment supports acid hydrolysis of cellulose, which manifests itself above all by a shortening of the polymeric chain [ 31 , 32 , 35 , 43 ].…”

Decoupling hydrolysis and oxidation of cellulose in permanent paper aged under atmospheric conditions

“…This difference is significant regarding the fact that 4 hygro buttons, two in two tubes, recorded the same variation with an accuracy of 0.5 % RH. Interestingly, other authors showed an important drop of RH during ageing in closed vials at similar temperature, with a decrease of 30 % in 80 days at 65 °C (Jeong & Potthast, 2021). They linked this decrease with the presence of water vapour flows outside the closed vials and, as the concentration in water influences the hydrolysis rate, they proposed a recalculation method to account for the loss of water.…”

“…However, tightening of the tubes must be adequate because leakage of humidity can occur. Some authors propose to monitor the weight of the tubes during the ageing to evaluate the possible flows of humidity and to correct the actual hygrothermal conditions with time (Jeong & Potthast, 2021;Sawoszczuk et al, 2008). Here, to ensure trustworthy experimental results, we evaluated the robustness and reliability of the accelerated ageing technique in closed tubes beforehand.…”

“…Three phenomena were examined in relation to this observation. Firstly, the hydrolysis of amorphous cellulose releases water as amorphous zones account for water adsorption sites(Jeong & Potthast, 2021;Tétreault et al, 2019). In contrast, this reaction consumes a water molecule per bond scission.…”