It is pointed out that fiber-curl ratio can not be defined as a local quantity assignable to each point on a fiber, and that hence the definition of its statistical distribution can not be an intrinsic property of a fiber network. The distribution of fiber curvature is instead proposed as a measure to express the overall characteristic of the degree of local fiber curl in a two-dimensional fiber mass. A method for estimation of this distribution is presented with an experimental verification.

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In this paper, a method for quantifying and characterizing the change of fiber bundle deformation during the twisting process, which relate to yarn structure closely, is described. Mean helical path difference between the two component fibers in both sides of fiber bundle (HPD) was proposed in order to study the form deformation. The HPD at unit length (HPD density; ρ) was measured by analyzing each cross sectional pattern of “two layer yarn” at 1mm intervals by an image processing system using a reflecting microscope, a TV camera, an image frame memory and a micro computer. It was observed that HPD density changed periodically and the average HPD density <ρ> varied depending on delivery direction. The average of the integration of deviation ρ-<ρ>, which may be net HPD relating to the periodical change, was independent of spinning parameters except spinning tension. It is explained in terms of HPD as the difference of fiber stretching extent in both sides of fiber bundle that the average deformation form and the degree of form varied with the delivery direction and the spinning tension respectively. The method described in this paper was useful for the study of twisting process.

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The relationships between the changes of stretching work or mechanical properties and the behavior of molecular orientation for uniaxially stretched Nylon-6 films prepared by wet process in water were discussed.
Following results were obtained.
(1) The degree of total molecular orientation can be simply expressed as a function of the logarithmic stretching work.
(2) The crystal orientation is oriented higher than that of the amorphous chain with increasing stretch ratio. And, the degree of orientation for amorphous chain is unchanged during higher stretch ratio.
(3) The linear relationship between the logarithmic stretching work versus Young's modulus of the stretched films is recognized.

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The changes in mechanical properties of PET cords annealed under various conditions and PET cord-rubber composites cured under some conditions were discussed by means of the results of thermal contractive force and discontinuous stress relaxation measurements. Thermal contractive force was measured at a heating rate of 20°C/min in the range of 25°C to temperatures below melting point of PET. Discontinuous stress relaxation was measured under initial load of 3 g/denier (194N). The duration for the release of stress is zero or 5 min. The composite consisting of cords treated at 200°C, which showed the generation of contractive force in a lower temperature range was higher thermal contractive force than that of cords treated at 240°C. The thermal contractive force of the composites was affected not only by the treated conditions of the cord but also by the cord tension on preparing the specimen. In the discontinuous stress relaxation test, the stress of the cords and the composites increased with repetition of stretching. When the strain recovery of the amorphous region of the cord hardly occurred in duration of intermission, the stress of the cord and composite increased extremely. It seems that the increase of stress under the discontinuous stress relaxation test is due to the strain hardening of tie molecular chains. The stress relaxation of the composites were larger than that of the cords. It seems that this phenomenon is influenced by the tie molecular chains of the cord which are relaxed rapidly at the initial stage of thermal shrinkage.

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Tensile fracture of a twisted-filament yarn is discussed on the basis of an idealized yarn model. In the model the yarn is assumed to be composed of several concentric-cylindrical layers, in each of which the constituent filaments form helices of a constant pitch. This simplification of geometry enables us to evaluate the twist schrinkages and the changes in radius of fiber and yarn that are brought about by twisting, as well as to obtain the relation between the elongation of yarn and that of fiber in each yarn layer. Based on these, probability distribution of breaking elongation for each layer is estimated from that of the original constituent fibers, and the effects of twist on fractures of yarn and fiber are analysed.

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The synthesis of poly (1, 4-butylene terephthalate) (PBT) prepolymer by direct esterification of terephthalic acid (TA) with butanediol-1, 4 (BD) was investigated. Preliminary experiments showed that the preparation of prepolymer without a catalyst is impractical, because considerable amounts of tetrahydrofurane (THF) and water were produced from BD by side reactions. In order to find out the catalysts which promote esterification reaction of TA with BD without side reactions, the catalytic effect of various metal compounds was examined. It was found that (i) some kinds of titanium and tin compounds were very effective as catalysts for direct esterification of TA with BD and (ii) when a monoalkyl tin compound was used as a cocatalyst, the catalytic effect of titanic acid ester was improved.
The effect of pressure, reaction temperature, and molar ratio of TA to BD on the formation of THE were also investigated in the presence of catalyst. Furthermore, an attempt to prepare the copolymer of PBT was carried out using isophthalic acid as an acid co-component. Useful informations on the optimal reaction conditions for preparation of copolymer of PBT was obtained.

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A simulation system is designed and made for research on dynamical behavior of the clothes, especially on swinging motion of the skirt, covering a human body on walk. The system is composed of two separate functional parts which mimics respectively the buttock and the leg motions of a young woman on walking. This paper describes the make and the performance of the former part (the buttock simulator).
The hip of a manikin (a nude) is installed on a motor-driven mechanism with plate cams of special design so as to rotate over certain angular ranges around two perpendicular axes. The period of the combined rotational motion can be varied from 0.3 to 3.0 sec. The behavior of this simulator is compared with that of the buttock of a woman on walk, the result of which suggests those are well alike.

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The fragments from the degradation of wool-Cu (II) complex by hydrogen peroxide have a partly ordered structure (α-helix) in water. As the pH increases, the partly ordered structure transforms into a random coil. Further, the fragments undergo random coil-α-helix transition in ethanol-water mixtures with increasing ethanol component. These behaviors are similar to those of charged polyamino acids, in spite of that the fragments of wool undergo a less sharp transition in comparison with charged polyamino acids.

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