Paper aged, fold-endurance data

Several empirical and semiempirical equations were applied to folding endurance and reflectance data from Kraft paper samples aged at 70-100°C. For both properties, better fits to the data were obtained with a plot of the logarithm of the property versus the square root of aging time rather than the aging time itself. Several schemes with consecutive, competitive, or reversible reactions also were considered, and from them equations were derived that also could describe the change of properties of paper with time. 

The data for the JCPA-60 paper aged fourteen and twenty-one days show that for the 20% -80% relative humidity range, the paper was of low strength. However, the highest folding endurance values were between 50% and 60% relative humidity. 

The data in Table VI shows that the Allied Superior paper improved in folding endurance test values as the relative humidity was increased. This occurred in all instances except for the paper that was aged seven days and tested at 30% relative humidity. 

The life of paper is commonly predicted by subjecting the paper to accelerated aging at temperatures ranging from 60-100 C, and measuring the decrease of folding endurance at several aging times. Extrapolation of a linear Arrhenius plot of the data to... 

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