The past geometrical methods for the strains of fibers in bent yarn are compared in this paper. It is assumed that the fibers in bent yarn have strains by bending and mutual friction forces on the contact line. To expand the four elements model by Dr. Murakami for the bending recovery of a single fiber, the non-linear visco-elastic model is used for the phenomena. The distribution functions of the retardation time and the friction between the fibers are divided into two parts by twists of yarn, the parts are discussed theoretically in this paper.

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The Studies on the crease of fabrics have concluded that bending the fabrics consists in bending the twisted yarn. But the cross sectional forms of the bent yarn have not yet been studied as they are concerned complicatedly with the forms and the properties of the single fiber and the twists of the yarn, and the forms of the cross sections of the bent fiber are studied in this paper before the cross sections of bent yarn are studied. The circular cross section of the original fiber becomes ellipse when it is bent and the ratios of its diameter to the radius of curvature are nearly equal to 1, although it varies with the kind of fiber and its denier. When the ratio go over 1, the sections take the form of beans; in the case of below 1, they remain nearly circle.

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As the model of a bent filament in a creased fabric a nylon filament was used and the stress distribution in the cross section of the bending plane and in the longitudinal direction was studied. As the results, it is known that the neutral axes exist on the compression side, and the bending stress give an effect on the non-bending part in the longitudinal direction, 2 to 3 times of the fiber radius, although the effect varies with the kind of the fiber and its denier. When a fiber of circular section is bent, the cross section of the bending plane is in the form of ellipse and so the stresses in the cross section of the bending plane are corrected from the study of elasticity. In this paper, however, it is assumed that the same relation between the double refraction and the stress holds good in the tension side as similarly as in the compression side.

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A Couette type viscometer was designed and constructed. The inner cylinder is supported by a pair of very small pivot bearings, and allowed to rotate with opposing brake torque proportional to the rotational speed. Actual measurements were performed on very dilute solutions of myosin B and tobacco mosaic virus in the range of shear rate of about 1 to 100 sec^-1.

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Electrophoretic studies were performed of the system containing two kinds of polyelectrolytes. It was found that in the descending channel the ratio of areas of the patterns agreed with the analytical mixing ratio of the components whereas in the ascending one this was not the case. The discrepancy was also found to be decreased somewhat with taking the concentration dependence of the transference number of the polyelectrolyte component into account with the aid of Dole's theory, but the satisfactory agreement with the analytical ratio was not obtained. Moreover the distinct displacement of δ-boundary was observed in the opposite direction to that of the polymer component. This observation, together with the above mentioned disagreement, was suggested to be due to the interaction of electrostatic nature, which was discussed in a previous paper.

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As the function of conversion the degrees of polymerization (P) in the vinyl polymerization could be expressed approximately by the following relationships, when a was assumed to be unity in the equation M_n=k [η]α:-
a) In the case of the solution polymerization in which solvent behaves as a telogen, where [M] is the monomer concentration, [S], the solvent concentration, C_s, the chain transfer constant of solvent, and x, the fraction of monomer converted to polymer.
b) In the case of the solution polymerization in which solvent behaves as a usual chain transfer agent, where P₀ and P_i are that in the bulk polymerization and that in the solution polymerization (x=0) respectively.
c) In the case of taking consideration of polymer transfer in a), where C_poly is the polymer chain transfer constant.
The equations of a), b) and c) were applied to the results in the thermal polymerization of styrene in the presence of carbon tetrachloride, and then justified quantitatively.

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Solution polymerization of vinyl acetate was carried out in acetone, methyl ethyl ketone, diethyl ketone, methyl isopropyl ketone and methyl isobutyl ketone at 60°C, varying monomer concentration from 60 to 100%. So obtained polyvinyl acetate was converted to polyvinyl alcohol and the content of carbonyl end group was determined quantitatively. Chain transfer constantsC_s, of ketones were evaluated from the carbonyl content. The estimated values of C_s, were 1.1, 6.0, 8.0, ca. 2.2, and 2.0×10^-3 in the order of ketones descrived above, respectively. On the other hand, C_s, values which were estimated from the polymerization degree of polyvinyl alcohol, were 1.1, 5.7, 9.8, 10.2 and 2.8×10^-3 respectively. The satisfactory agreement of the results by the two methods except for methyl isopropyl ketone supports that carbonyl group is introduced to the end of the polyvinyl alcohol as expected from the kinetic study of the polymerization in ketones.

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In the polycondensation reaction of some N-Carbo-substituted-phenoxy derivatives of DLalanine, effects of solvents, substituent groups, temperature, time and monomer concentration on the yield and the reduced viscosity of polymer products have been studied. A most suitable solvent for polycondensation is nitrobenzene, in which the reduced viscosity of products is about twice higher than in pyridine-toluene mixed solvent. From the results of polycondensation of various N-carbo-substituted-phenoxy-DL-alanine at 100 and 120°C, it is shown that the reaction rates become slow in the order of o-NO₂, p-NO₂, H, o-CH₃ and p-CH₃. In the unsubstituted compound its polycondensation proceeds comparatively fast at 120°C. In general, the yield and the reduced viscosity of polymer are linearly increased with the time of polycondensation, however, its extent decreases in the nitro-substituent. In the methyl-substituent it polycondensates very slowly at 100°C, while exhibits an analogous tendency to behavior of the unsubstituent at 120°C. Monomer concentration is prefered to about 6%.

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It is shown that poly-DL-alanine solutions in dichloroacetic acid exhibit a typical polyelectrolyte behavior. Thus, solutions of poly-DL-alanine in anhydrous dichloroacetic acid show the characteristic steep rise in reduced viscosity as the polymer concentration approaches zero. The addition of water to such solutions reduces the dilute solution viscosity, but a relatively large amount of water is necessary to repress the polyelectrolyte behavior completely. The polyelectrolytic character of these solutions is attributed to partial ionization of the amide groups along the polymer chains. From the results of the visosity measurement on the solutions of various poly-DL-alanine in 80% dichloroacetic acid, it is shown that a linear relationship exist between reduced viscosity and intrinsic viscosity at a definite polymer concentration. The intrinsic viscosity is slightly less in m-cresol than in 80% dichloroacetic acid, and is very small in formic acid.

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