Accelerated Aging of Paper: Can it Really Foretell the Permanence of Paper
Accelerated Aging within Sealed Enclosures
A more realistic accelerated aging of paper can be achieved by equilibrating it to a characteristic moisture content under standard conditions, and then enclosing it in an air-tight container before subjecting it to an elevated temperature.
Aging within sealed enclosures has been undertaken previously by several workers (Richter, 1954; Czepiel, 1960; Browning, 1968, MacClaren, 1980). However, until now the intent of all such experiments has been to retain the moisture content of paper. Also, since these studies mainly compared the aging of sealed humidified paper against open sheets in a dry environment, they attributed the observed increase in the aging of acidic paper inside sealed environments to the presence of moisture and missed the added effect due to the accumulation of acidic degradation products.
At the Library of Congress, we have undertaken extensive experimental work for the aging of paper within sealed enclosures. These experiments have included aging of paper within aluminized PET bags and also within glass tubes. In Figure 3, we present some of this work, which compares the loss of fold endurance for different amounts of paper sealed within aluminized PET bags and aged at 100°C . Also shown in the same figure data for paper within stacks aging at 90°C and 50% RH to provide a frame of reference.
Although the temperature for aging of the paper in a stack is ten degrees lower, yet the enhancement of the rate of degradation achieved within and air-tight enclosure is evident. An increasing mass of paper within the same enclosure leads to a faster rate of degradation. This observation is easily explained. A higher amount of moisture within nearly the same space may understandably raise the level of relative humidity within the enclosure and thereby, the rate of degradation of paper. However, in this respect this work presents data that are contrary to the observations reported by Richter (Richter, 1954).
Table of Contents - Introduction - Status of Accelerated Aging of Paper - Research in Accelerated Aging of Paper - Comparison of Accelerated Aging of Paper in Stacks and Sheets - Aging of Paper Sealed within Polyester Film - Inadequacy of Single Sheet Accelerated Aging Methods - Accelerated Aging within Sealed Enclosures - Comparison of Accelerated Aging Methods - Accelerated Aging under Light -Measurement of Rates of Degradation - Conclusion - References - Supporting Documents