A Research on the Strength of Kraft Paper

Abstract

A lot of researches have been announced about the relation between the tension given to sheet and the strength of accomplished paper in the process of drying sheet. These researches, however, every of them, are described that by adding a constant tension or threegraded tension to sheet in the process of drying it, it should be dried and, then analized. According to this method, therefore, it seems difficult to understand well in what quantity of water, how much effect, tension which is given in the process of drying, gives to sheet. Now, the experiment which I am going to make is as follows. We add tension to sheet the moment it contains a certain quantity of water, and later dry it under the same condition. In comparison with the sheets which is given no tension and dried under the same condition, I intend to analize how much effect, tension gives to the accomplished paper, in what quantity of water.Conclusion1) If tension is given, in machine direction, to wetsheet which contains 70% of water, accomplished paper reduces both its logitudinal and lateral tensile strength and expansion.2) When we extend longitudinally wetsheet which contains 70% and 60% of water, the side of wetsheet indicates shrinkage in proportion to the expansion of the length. The difference of shrinkage which results from the difference of expansion keeps the same degree not only in the process of drying but also in the accomplished paper. The ratio of the longitudinal expansion to the lateral shrinkage is nearly 1 to 0.64 in every case.3) When we extend wetsheet longitudinally as long as long as 3%, 2%, and 1% of its length which contains 70% and 60% of water, perfectly preventing it from its longitudinal shrinkage, the ratio of lateral shrinkage of the dried paper is 6.7%, 6.06% and 5.50% respectively.4) When we extend longitudinally wetsheet (70%55% of water) as long as 1% of its length and, dry it, keeping its expansion, the dried paper reduces 0.5%0.7% of its longitudinal expansion. When we extend it longitudinally as long as long as 2% and 3% of its length, it reduces its longitudinal expansion at the same rate. On the contrary, it increases 0.2%0.4% of its lateral expansion.5) When we extend wetsheets which contain various quantity of water (70%55%), if the ratio of expansion is identical, the strength of accomplished paper has very little difference among them.