When filaments are produced by wet spinning, non-circular cross section can be obtained.
The cross section of P.V.A. filaments which are spun by wet spinning are “dumb-bell” form and their inner parts are different from outer parts.
These characters are observed in the samples spun by different coagulating bath and polymer solution.
It is found that the main factor for the wet spinning is imhomogenity of coagulation process.
By observating the inner construction made by filling with the pigment and breaking the construction, it is found that inner parts consist of vacuous and weak structure.

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The authors found that the wet strength of paper is increased only by the heat treatment, and the strength obtained is almost as much as those of the melamine or urea resin treated papers. The fundamental mechanism of the development of the wet strength is discussed, and influences of imbibed water, oxidations, acids and salts are investigated as reported in a series of previous papers.
Influences of the lignin content and the morphological factors of the fiber on the heat treatment of paper are treated in the present paper. Being subjected to heat treatments, the wet strength development is interfered by the presence of lignin. But the strength development decreases with lesser lignin content. This seems to be caused by change of the other effective components or parts. The beating of the fiber is not so much effective to the wet strength development as to the dry strength development. It is not the case that finer fibers are more susceptible to the effects of the heat treatment. Papers made from cotton and viscose rayon as well as from wood pulp show the wet strength development at the heat treatment, but their strengths and ratios of the wet strength to the dry strength are markedly different from each other. These differences seem to owe to. the morphological factors, but to be more related to the other microscopic factors, for instances, the accesibility of the original fibers or the hemicellulose content. The lower D. P. cellulose molecules are not so sensitive to the heat treatment as low as 130°C, but more sensitive to the higher temperature treatment of 190°C than the higher D. P. cellulose molecules.

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For the P. V. A. fibre added various amounts of Tetramethylene Diisocyanate (T. M. D.), and the following several properties were examined; heat resistance (softening temperature), water resistance (contraction in hot water), and elastic recovery and strain-stress relation (Young's modulus).
These properties were clearly improved by increasing the T. M. D. content. The sample, swelled enough and reacted uniformally, tended to display rubber-like elasticity, especially in water. The result is probably due to Diurethane crosslinkage introduced moderately between P. V. A. molecules.

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The relations between the chlorination process and some mechanical properties of treated wool fibers is discussed under the same conditions as reported in (I). Results obtained are as follows; (a) Although decrease of finess and loss of weight have a proportional relation, dissolution takes place not only on surface, but in inner part of fibers. (b) Stress for extension per unit area drops gradually in accordance to proceeding of modification, and it has a proportional relation with reduction of cystine linkages. Consequently, reduction of cystine linkages is the most responsible factor in dropping the stress. (c) Drop in breaking strength has more remarkable tendency in wet state than when dry. (d) Both elastic recovery and resilience of wool fibers do not change by chlorination, and therfore the elastic properties are not responsible for unshrinkability in chlorination, except that of scales ascertainable by frictional properties.

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