Elastic recovery of Vinylon N is excellent, but its resistance to heat in dry and wet conditions isnot quite sufficient, and the range of suitable degree of acetalization is comparatively small. Thesedisadvantages may be overcome by formalization before or after acetalization with nonytaldehyde, and the elastic recovery of fibers thus obtained is also better than that of the ordinary Vinylon.

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Generally, acetone and aqueous solution of caustic soda do not mix but they separate into two layers, accompanying the volume constraction of caustic soda solution. Only small amount of the caustic soda enters into acetone part, so the concentration of caustic soda solution increases.
The authors have applied this phenomenon to the dilute viscose and have succeeded to concentrate the dilute viscose without decomposition of xanthate.

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Light resistance of polyvinylchloride fibers drawn to various extent were studied and the following results were obtained.
Tensile strength (g, g/d) and elongation (%) decrease by lengthening the time of exposure, but its degree changes by ratios of drawing of the fiber.
In the drawings under 400%, their tensile strength (g) are found to be of the same value when exposed for over 12hrs., while in the drawings over 400%, tensile strength (g) show smaller value than in the cases under 400%.
Decreases of tensile strength (g/d) become larger in the fiber of the higher drawings than in the lower.
On the contrary, decreases of elongation (%) become larger in the fiber of the lower drawings than in the higher.
Differences of tensile strength (g/d) and elongation (%), are caused by drawing to various extent; they become smaller as exposure time is increased.

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The series of this report will be related to the influence of intentional tension differences given to the parts of the yarns during preparation and weaving of viscose rayon fabrics of plain weave, and to the fabric defects. The defects are supposed to appear through non-uniform fabric structures and uneven adsorption of dyestuff by the yarns.
This report (1), deals firstly, the mechanical properties of yarns excludeing the influences which may come from the irregular properties of the yarns, and secondly, the yarn tensions in prepearing and weaving processes were actually measured. The results are as follows.
(1) The difference of the creep properties between the cones was not recognized in cases of long yarn specimens, but it appears in the cases of short specimens.
(2) Instantaneous elongation is proportional to the load, and when the load is taken off such elongation disappears also instantaneously.
(3) The weight of the sized yarns varies according to the sizing tension, and also the composition of the sizing liquid which changes gradually during its use.
(4) The irregular unwinding tension is often seen at the root of the cop.

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In order to estimate the weft pirn, its hardness must be expressed numerically. In this research, three instruments are used, (1) rubber hardness tester, (2) pressure type hardness tester with cylindrical bars and (3) the same tester with surface plates.
The surface plate type is better than the others, and 3kg loads are more appropriate when thickness of yarn layer is over 5mm, 1.7kg loads for 3_??_4mm.

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We studied the mechanical properties of the viscose spun rayon fabrics (muslin), which were treated with formaldehyde present in various alcohols under acid catalyst. These alcohols used were methyl alcohol, ethyl alcohol, ethylene glycol, glycerine, glucose, sucrose, soluble starch, polyvinyl alcohol, and carboxy methyl cellulose. Viscose spun rayon fabrics were immersed 5min. in treating baths, which contained H • CHO 12 gr., HCl 0.1 gr. in 100cc., and respectively suitable amounts of alcohols decribed above. Then squeezed and dry heated 10min. at 120°C.
In the case of alcohol of lower class and of low boiling temperature present in the process of reaction between cellulose and formaldehyde, the alcohol escapes readily from the reaction system in the first stage of the dry-heat treatment, so the mechanical properties of their treated fabrics were not affected.
However, in the case of alcohol of higher boilling point, it remaines and reacts on formaldehyde. that its amount is decreased for cellulose to react on.
Of the latter, those alcohols are divided into 2 groups from their resultant mechanical properties of fabrics. In the first group are ethylene glycol, glycerine, carboxy methyl cellulose, etc., which protect from decrease of tensile strength and elongation, and at the same time, decrease the improvement of the crease resistance. In the second group are those which little affect the crease resistance, but polyvinyl alcohol does not prevent the reduction of tensile strength and elongation.
Glucose and sucrose belong in the first group, but their effects are comparatively small.

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It is assumed that the stiffness, compressibility and coefficient of friction of a fabric are the main factors in handling the fabric. According to the idea of Dr. D. H. Gunter (Am. Dyes. Reptr., 41, 167, 1952) resisting forces of fabrics, when they are drawn through a ring-hole, were aimed at and carefully observed to acertain whether they give us proper means to indicate the fabric hand as a measurable quantity, or not.
A circular test-piece, say 30cm diameter is supported at its center and drawn through a hardchrome plated metalic ring-hole. Withdrawal resistance gradually increases as the ring descends, because the calculated density, or fullness of the hole, increases from time to time as the ring descends relatively to the position of the test piece. In this respect, the authors found the following experimental relations. where F: withdrawal resistance A₀: inner surface area of the ring-hole ρ: fullness of the hole expressed as a ratio of sectional area actually occupied by the fabric to the area of the narrowest section of the ring-hole. α, β₁, β₂ constants, depending upon the character of the fabrics.

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