Abstract:

In this paper,first,an accelerated thermal aging of paper was carried out,and the corresponding pyrolysis process was analyzed via the thermogravimetry. Then,the thermogravimetric characteristics of the paper during the aging were investigated,finding that the weight loss in the pyrolysis process contains two stages,namely the dehydration
of paper and the weight loss caused by cellulose pyrolysis. TG kinetic analysis shows that the nonageing paper has the lowest activation energy,that the activation energy first increases and then decreases during the aging,and that,with the increases in aging time and temperature,the thermal stability of paper degrades,the temperature
corresponding to a pyrolysis conversion rate of 0. 5,namely θ_0.5 ,gradually decreases,while the gap Δθ_0.5 between the θ_0.5 values of aging and nonageing paper progressively increases. Moreover,it is found that there is a quantitative exponential relationship between the relative polymerization degree DP /DP₀ and Δθ_0.5 ,which means
that Δθ_0.5 can be used as a parameter to evaluate the aging degree of paper. Based on the above-mentioned findings,a model to rapidly and quantitatively evaluate the paper aging can be established by means of thermogravimetry,which is proved effective by the accordance between the evaluated and the experimental results.

Key words: paper, thermal aging, thermogravimetry, activation energy, evaluation model