Kraft paper folding endurance

The above results agree with those of the folding endurance test carried out at 100°C—i.e., the Allied paper is most stable, the Foldur Kraft least stable, and the JCPA-60 is intermediate. 

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 cured sheets were conditioned at 23 °C and 50% relative humidity. MIT folding endurance was run on 1.5-cm wide strips at 0.5 kg load. Tensile was taken on the same width strip. Eight strips were run machine direction and eight cross direction. As mentioned by Raff et al. (4,5), standard deviation and coefficient of variation were increased greatly in the treated plasticized paper for example untreated Foldur Kraft gave ... 

Table III. Number of Times Folding Endurance Increased for Foldur Kraft Paper Samples for the Relative Humidity Range of 20% to 80%...

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