Use of the idea of “Unit change” is handy in research on the change of the density function of fiber leading ends. “Unit change” means the behavior of a unit fed-fiber bundle in the draft-breaking process. A unit fiber bundle is a bundle in which there are fiber leading ends at one point in the longitudinal direction. “Unit change” is discernible from the density function of breaking the point, delivery points and staple length . The behavior of a common fiber bundle is obtainable as the integration of unit changes.

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With a Schiefer-type abrasion tester we have investigated effects of the various factors, including the density and roughness of fabrics, the presence of a lubricant on fabrics, the abrasion speed on fabrics and the applied tension in fabrics, on the abrasion resistance of fabrics. We have drawn the following conclusions from the results of the investigation :
(1) Whether the abradants are emery paper or a steel blade, the abrasion resistance of fabrics generally increases with an increasing in their density.
(2) The abrasion resistance of fabrics generally decreases with an increase in the roughnessof under-fabrics.
(3) The abrasion resistance of fabrics increases with an increase in the thickness of the component yarns.
(4) The abrasion resistance of fabrics generally increases with an increase in the amount of the lubricant present. However, if fabrics get wet, the abrasion resistance of cupra fabrics decreases, but that of acryl and nylon fabrics remains unchanged or increases.
(5) With emery paper used, the abrasion resistance of fabrics remains unchanged even if the abrasion speed increases. With a steel blade used, the abrasion resistance of fabrics decreases.
(6) With emery paper used, the abrasion resistance of fabrics decreases with an increase in applied tension. With a steel blade used, the abrasion resistance of fabrics decreases.

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Pilling on wool fibers is serious defect which should not be left unnoticed. we have investigated the behaviors of the formation and wearing off of pills in knit goods by using the sponge-and-brush pilling tester.
(1) A distinct trait of the pilling of wool fibers is that-pills form rapidly and have a longer life than the pills of other specimens (e.g., acrylic, cotton and their blends.)
(2) The weight of a pill changes with the passing of abrasion time. It has a maximum weight point and increases gradually until it reaches that point.
(3) The weight of a pill takes a maximum value when the velocity of weight-forming equals the velocity of the wearing off of weight. Until they are equal, the velocity of weightforming exceeds the velocity of wearing off and helps to increase the weight of pilling.
(4) The weight of a pill is proportional to the amount of fuzz which is generated on a knit goods.
(5) The maximum velocity of weight-forming arrivesslightly later than the maximum amount of fuzz on knit goods.
(6) The amount of fuzz generated tends initially to increase sharply as a function of sponging time, then levels off as it approaches a nearly horizontal asymptote. Therefore, shearing in the early stage of abrasion time is an efficacious method of pilling control.

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We have built a low-temperature tensile tester and used it to test the tensile strength, breaking elongation and toughness of synthetic fibers.
The strength and elongation curve of synthetic fibers at a temperature of -50°C-+70°C can be expressed by a quadratic curve for strength-temperature and by a nearly straight line for elongation-temperature.
The products of these two equations can be expressed by a cubic curve as a function of the work of rupture versus temperature, and generally they have maximum and minimum values.
It seems that the cubic equation deduced from these two equations almost coincides withexperimental results.
The maximum value of a nylon fiber is obtainable at a temperature of about-20°C.
The work of rupture of 70d nylon yarn, 15cm in gage length is given by the following equation :
W₂=9.7×10^-3T³-7.95T²+2150T-191000
where W₂ : work of rupture (g·cm)
T : absolute temperature (°K)

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An apparatus to determine the bending modulus of strips by the vibrating reed method has been devised. Samples are driven by electrostatic force and their movement is detected acutely by a photo-transistor instead of a microscope. The resonance and measuring magnitude of the amplitude are determined by observing Lissajou's figures displayed on a cathode ray tube with the vibrating signal and the driving signal of the samples. Such electronic devices make possible detection under smaller amplitudes of the vibrations than microscopic observation in the conventional apparatus. Therefore, it is possible to reduce errors caused by departures from the ideal behavior of sample vibrations, any distortion in its frequency response curve and personal errors in measurements.
For samples of filamentus form, the apparatus also is used in vibroscopic measurements of mass per unit length (denier) of it. Therefore, if the density of the test pieces is known, its bending modulus can be determined easily with this apparatus alone. Some interesting and, usefull results have been obtained as to the characteristics of photo-electric detection. and an attempt of interpretation of these data is described. A method to clamp samples has been specially devised for the electrostatic drive.

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