Viscose rayon is at first immersed in water, the imbibition water is displaced either with liquid solvent or vapor, and then acetylated using sulfuric acid (sulfoacetic acid) as a catalyst. The method of displacement has no significant influence on the acetylation rate. As imbition liquid not pure water but salt solution is used, the water is displaced with acetic acid or ethyl acetate vapor and then acetylated, whereby salt, which remains in the fiber reacts, as a catalyst. Kinds of imbibition liquid and salt have much influence on the reaction rate. Salts which have only a small affinity to acetic anhydride such as zinc sulfate, disturb the displacement with the acetylating bath, whereas salts which have great affinity to acetic anhydride such as potassium acetate make the displacement easier. Viscose rayon may be acetylated smoothly with impregnated potassium acetate without imbibition liquid.

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Cotton yarn was acetylated in fibrous form using sulfuric acid (sulfoacetic acid) catalyst in liquid phase. It may be very smoothly acetylated after a short pretreatment with acetic acid. Count of yarn has almost no influence on the acetylation rate, for cotton yarn can be acetylated as easily as cotton fibers. Acetylation rate of raw cotton yarn is somewhat lower but it may be bleached after the acetylation. In comparison to viscose rayon, amorphous part of cotton is more easily accessible to organic liquids, so that the pretreatment for acetylation is simpler in the latter case.

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Cotton yarn was acetylated in fibrous form using perchloric acid catalyst in liquid phase. Under appropriate conditions acetylation takes place smoothly and highly acetylated fibers may be obtained easily. In this case a wider range of imbibition liquid may be employed than by the acetylation with sulfuric acid. In contrast to acetvlation with sulfuric acid catalyst cotton is more easily acetylated under the same conditions than rayon. It is noteworthy that perchloric acid acetylation bath decomposes gradually, wheras sulfoacetic acid bath remains stable.

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Intrinsic viscosity of several kinds of cellulose nitrates in acetone was measured related to its degree of nitration and degree of polymerisation by osmotic method. The following observations are made:
(1) _??_η_??_=K.P^_??_ is established over a DP range 90-3000.K=1.95×10^-3, α=0.91, (N%=ca 13.8%, 20°C, c: g/l)
(2) K is constant indepedent of their degree of nitration. α varies with their degree of nitration (N%) and the following relations were obtained:(a) Over N%=11 α=0.835 N²-0.162N+1.553 (b) Over N%=12 α=0.93-0.055(14.14-N) K=1.95×10^-3
(3) Influence of degree of nitration on the flex angle of cellulose nitrate molecules was calculated from Nukushina-Sakurada's viscosity formula of slightly crooked linear molecule. Sine of flex angle varies with the degree of nitration in the same tendency as in α.

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The effects of the pretreat-swelling of the NaOH-H₂O-PVA powder and the addition of surface active agents (Brij 30-35, Sanisol C and Setamol WS) on the average valae and the distribution of the degree of cyanoethylation in the vapour phase preparation of the water soluble polyvinyl cyanoethyl ether were studied. Although the pretreat-swelling and the addition of active agents give almost no effects on the average degree of reaction, the former increases strikingly the precipitation temperature of the water solution of polyvinyl cyanoethyl ether (_??_20 mol %) in the swelling time of 0.5-2hrs, showing the repression of a distribution of the higher degree of reaction, and the latter shows a small increase of the precipitation temperature.
Furthermore, the fractionation experiments of the degree of reaction seem to show that the addition of active agents produces effects on the simplification of the frequency distribution of the degree of reaction, especially in the case of 1% Brij/PVA wt.

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The degree of primary swelling, the cross-section stainning and the lateral order distribution were investigated with regard to viscose rayon spun in bath of various concentrations of H₂SO₄ and ZnSO₄ respectively.
The degree of primary swelling depends on the fine structure, that is, the broken-skin filament shows higher degree of swelling as compared with the normal skin-core filament.
The lateral order distribution of the broken-skin filament is different from that of the normal skin-core filament; the former has a peak in the region of higher lateral order.
The broken-skin structure is observed with a filament which is spun in both H₂SO₄ and ZnSO₄ poor bath. When the concentration of ZnSO₄ in spinning bath is high, the skin formation is accelerated so that the thick skin encloses the core completely.

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In order to measure the crimp content of fibers numerically, three methods were applied; (a) which is derived from the wave-length of crimp, (b) from the Japanese Industrial Standard and (c) from strain-stress curve of the crimped fiber. It may be concluded that the method derived from the strainstress curve of fiber was the most reasonable. In this method, the crimp content was calculated from the distance between the origin and the intersecting point of co-ordinate and tangent which is made at the 7% elongation of stress-strain curve of the fiber. From this distance the value of crimp content was calculated.
In view of the application as well as the theoretical evaluation of the test result, the permanence of crimp is more important than the crimp content. Then the loads varying from 5 to 15% of tensile strength of the fiber were given to crimped fiber twenty times repeatedly, and the decease in crimp content was measured.
As the result of the above tests on various kinds of fibers, it was shown that both the crimp content and the crimp permanence were greatest in wool.

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The effect of linear density on the tensile mechanical properties of sliver-like fibre system was investigate. Samples of direct draft cutting sliver, having the varieties of linear density with constant density, were tested for their load-elongation relation, lateral contraction due to extension, and degree of elasticity under cyclical repeated loading.
The experimental results show that:
(1) the cross sectional area of sliver is proportional to the linear density,
(2) the breaking strength is proportional to the linear density,
(3) initial Young's Modulus, poisson's ratio, breaking elongation and degree of elasticity examined with unloading at constant elongation are independent on the linear density, while they are affected by constituent fibre properties, structure factors of sliver and lubricant agents.
These observations suggest that the mechanical properties of sliver-like fibre system having constant density can be predicted from the measurements of fineness counts of sliver fully as well as from determination of sliver structures and data of single fibre properties.

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In dyeing yarns coiled on a cylindrical bobbin or reel or in immersing in water raw silk or pot cake packed in the form of a cylinder before rereeling, water permeability is one of the most important problems.
In this paper, we deal with this problem, especially the method of its measurement. The flow through layers of cylindrical yarn may be expressed in the following equation, the gravity flow being neglected.
where Q: total flux through the yarn layers in unit time, k: constant, l: width of layer, p: pressure head, μ: coefficient of viscosity, γ_e and γ_w: outer and inner radii respectively.
It has been experimentaly found that this equation is fit for sufficiently thick layers (more than 3 rolls) at the low Reynolds numbers.
In case the thickness of yarn layer is not uniform, for instance barrel or cone package, γ_e is the function of Z (axis coincides with bobbin axis), and so when this function is known, we can obtain Q-γ_e (Z) relation from the integration of γ_e (Z) along Z axis.

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Heat setting of nylon was carried out by dry process. And the equilibrium and the rate of dyeing were studied. The experiment showed that the amounts of absorbed dyes at equilibrium, and the rate of dyeing decreased by heat setting.
From the experimental results, it was suggested that the changes of inner structures, expressly crystallization, were caused by heat setting, therefore the amounts of amino end groups in amorphous parts decreased, and then the paths of diffusion decreased too.

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