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P. Mäkelä. Effect of drying conditions on the tensile properties of paper. In Advances in Pulp and Paper Research, Oxford 2009, Trans. of the XIVth Fund. Res. Symp. Oxford, 2009, (S.J. I’Anson, ed.), pp 1079–1094, FRC, Manchester, 2018.


Results in the literature disagree regarding the effect of drying temperature, final drying time, and drying constraint history, respectively, on the in-plane tensile properties of paper materials. Furthermore, it is debated whether the in-plane tensile properties are controlled by the final drying stress or by the total strain during drying.

In this work, the drying mechanics of a pilot machine-made paper grade was studied. Wet paper sheets were collected after the wet press section. The sheets were dried in a laboratory dryer using different drying constraints. The supplied heating power, the ambient climate, and the ventilation of the paper sheets were controlled during the drying trials, which made it possible to independently alter the drying temperature and the final drying time. The dried sheets were conditioned in 23°C and 50% RH before tensile testing.

The results showed that the tensile stiffness, tensile strength, strain at break, and tensile energy absorption of the dried sheets, respectively, were linearly related to the total strain during drying of the sheets. These linear relations were shown to be unaffected by drying temperature, final drying time, and drying constraint history. On the other hand, the corresponding relations between the in-plane tensile properties and final drying stress were found to be both non-linear and greatly dependent on the drying constraint history.


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