2017 年 71 巻 9 号 p. 1033-1041
Research was conducted to clarify the relationship between natural ageing and accelerated ageing of paper using paper naturally aged for 80 to 130 years. Following a previous report on a test regarding the degradation behavior of paper samples using suspension method（80℃, 65％rh），same paper samples were artificially aged by sealed tube method（80℃）to clarify the physical and chemical ageing behavior of paper.
As a result of the present experiment, it was found that it is desirable to use degradation rate indicators （dividing degradation rate by current physical value prior to accelerated ageing）in sealed tube method as well for the ageing index of the physical strength of JCS samples instead of the degradation rate. Based on this result, it was further found that the degradation of the physical strength and discolouration of paper in sealed tube method was more severe than those in suspension method but that changes among paper samples indicated similar tendency in both methods. Moreover, as in suspension method, the more organic acids had accumulated in the paper, the larger the degradation rate indicators of tear and burst indices and discolouration rate were in sealed tube method. These degradation rate indicators were correlated to the number of cellulose chain breaks. From these results, it may be said that broken cellulose chains have much to do with the decrease in the physical strength of paper and that cellulose chain breaks are caused independent of the kind of acid, oxidation contributing as much to the break as hydrolysis.
