Polypropylene filaments drawn at 98°C were subjected, under tension or tensionless state, to dry heat-treatment or to wet heat-treatment in polyethyleneglycohol of lower molecular weight, at 100_??_140°C. Shrinking behaviour in heat-treatment and properties of heat-treated filaments, such as density, birefringence, Young's modulus, disperse-dye absorption and shrinkage in boiling water, were observed. The results obtained were as follows.
i) Heat-treatment under tensionless state: Filaments shrink more in wet heat-treatment than in dry heat-treatment, and thus birefringence decreases more by the former treatment than by the latter. Density increases by heat-treatment, especially greatly by wet heat-treatment; this is supposed to be caused by the increase of the degree of crystallinity. By wet heat-treatment, however, Young's modulus seems to rather decrease and dye absorption increases remarkably. Dimensional stability to boiling water is better for filaments wet-heat-treated than for those dry-heat-treated.
ii) Heat-treatment under tension: The effect of heat-setting is more remarkable in wet heattreatment than in dry heat-treatment. The increase of the tension in the treatment increases the density and Young's modulus.
iii) The above tendencies are increased with rising temperature of treatment, especially greatly above 120°C. We may conclude, therefore, that the optimum temperature of heat-treatment for polypropylene fibers is 120_??_130°C. Furthermore changes in fiber structure by heat-treatment were discussed, in connection with the role of heating medium for loosing the packing of intermolecular structure in the amorphous regions.

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Because of the irregularform of the cross-section of viscose rayon fibers, measurement of the fiber-thickness at a given point, where reterdation is measured for determination of the degree of birefringence (D. B.) is generally difficult. Although a few methods of mensuration have been applied to measure the fiber-thickness, a more accurate one was presented determined in this paper as follows: by cutting the end of a fiber at 45° angle, turning the fiber exactly 90° angle round the fiber axis under a microscope, and then measuring the fiber-thickness at the part where the retardation was measured.
Assuming that thickness of skin along the cross-section is constant, and also the D. B. of skin and core are uniform in themselves, D. B. of skin and core parts of a fiber was determined from the difference between D. B. of the major axis direction of the fiber and that of the minor axis direction, respectively and the following results were obtained;
(1) As D. B. of the skin part increased, strength, Young's modulus beyond yield point and height of yield point of the fibers increased, and on the other hand, elongation, knot, loop-, and bending strength decreased.
(2) D. B. of the core part has no influence on the above-mentioned physical properties of the fibers.
(3) The so-called apparent D. B. is dependent upon D. B. of the skin parts.

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Graft copolymerization of styrene to polyvinyl alcohol (PVA) films was attempted using potassium persulfate and α, α′ azo-bis-isobutyronitrile as initiator. In the presence of water, up to 700% styrene were grafted to films, whereas in the absence of water, no styrene was grafted. Furthermore, styrene was grafted to PVA fibers swelled with water at room temperature. Fibers obtained showed good resistance to hot-water, excellent elastic recovery at low elongation, and good heatsetting property.

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Photo-polymerization of vinyl acetate was carried at 0°C and -30°C using uranyl acetate as sensitizer.
Polyvinyl acetate thus obtained was saponified to polyvinyl alcohol (PVA), and the properties of this PVA and fibers prepared from it were compared with those of commercial PVA.
The contents of 1, 2 glycol structure of PVA decreased and the gelation of aqueous solution was accelerated with lowering polymerization temperature of polyvinyl acetate from which the PVA was produced.
Heat treated and not formalized fibers prepared from this PVA had good resistance to hot water up to 110°C, and its tenacity, elongation and elastic recovery were not inferior to the fibers from commercial PVA.

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In our previous reports on the spinning mechanism of viscose rayon, it was concluded that fresh regenerated cellulose gel inherited its internal structure from the cellulose xanthate gel, the distinctive property of which had been determined by the coagulation condition.
In this report the internal structure of the dry cellulose gel was studied to find the effect of drying on the stucture of the gel. After drying, the degree of swelling upon reswelling reduced considerably, which was attributed to the formation of new junction points. However, the frame work of the gel structure did not change during drying greatly, so that the inherent characteristics of the gel, such as orientation and thermal stress, were similer to those of the regenerated cellulose gel before drying.
As the summary of our studies, we can conclude that there are several factors which influence the internal structure of the regenerated cellulose gel, but the most important factor is the condition of coagulation.

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In the previous paper, we confirmed the two reasons why the Sivola process gave higher yield of pulp than ordinary process. The alkaline digestion of the Sivola process, however, is characteristic in containing sulfite spent liquor from the first cooking stage. So we examined how the presence of sulfite spent liquor influences the yield of pulp in the alkaline digestion.
The results are as follows;
(1) The presence of sulfite spent liquor prevents the degradation of alpha-cellulose during the alkaline digestion, but gives no particular effect on the dissolution of low molecular substances, which is considered to be governed by the character of the cooking liquor.
(2) The effect of the presence of sulfite spent liquor in the alkaline digestion is caused by the reducing substances in the spent lipuor as well as its strong buffer action in the weakly alkaline region.
(3) Irrespective of the presence of the sulfite spent liquor, digestion with the mixed solution of sodium carbonate and sodium sulfite gives higher yield of pulp than that with caustic soda solution for a given alpha-cellulose level.

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Some experiments were carried out to find out the reaction between cellulose and dimethylol urea in predrying or baking process of urea formaldehyde resin finishing of the fabric. Namely, the author investigated the decomposition of s-bis methoxy methyl urea at various temperatures in the presence of HCl and the reaction of dimethylol urea with n-butyl alcohol at boiling point of the latter.
The results obtained are summerized as follows.
(1) At 75°C (predrying temperature) s-bis methoxy methyl urea in aqueous solution of pH 5.0 was unstable and produced a great amount of metylol groups by the hydrolysis of ether linkage.
(2) In the reaction of dimethylol urea with n-butyl alcohol at boiling point of the latter, the formation of methylene urea became predominantly with the increase of acid concentration, though a small amount of ether formation was still accompanied.
(3) s-Bis ethoxy methyl urea, when heated with an oil bath continiously passing dry HCl gas, liberated ethyl alcohol of about 85% of the theoretical value.
From these results, there is little tendency of formation of ether cross linkage between cellulose and dimethylol urea in the case of urea formaldehyde resin finishing of fabric.

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