Y. Sawaragi and H. Tokumaru advanced a phenomenological theory of visco-plasto-elasticity derived from a mechanical model composed of three kinds of elements---spring, dashpot and slider (Coulomb's frictional mechanism) ---to explain non-linear visco-elasticity. Here we discuss the applicability of this theory for non-linear relaxation. The necessary condition for applying the theory to relaxation is:
∂/∂ε₀ [-∂E_r(ε₀t)/∂ 1n t]>0
where
E_r(ε₀t) : Relaxation modulus at time t in the strain ε₀
The relaxation behavior of polyethylene (reported in previous paper) did not satisfy this condition and, accordingly, could not be represented by Sawaragi and Tokumaru's equation.

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Previously, we considered the stress relaxation properties of polyethylene under relatively small deformation( 1-5 %) and showed that relaxation stress σ_r (ε₀, t) could be represented by this equation:
σ_r (ε₀, t)=α Ε (1-β₁ ε₀+β₂ε²₀) t^-n…………………………………(1)
By applying the superposition principle, stress-strain relation under a constant strain rate can be derived from the above equation as follows:
σ(ε)=α epsilon;/1-n{1-2β epsilon;/2-n + 6β epsilon;²/2(2-n) (3-n)}t^-nααα(2)
In other words, the strain and time dependence of stress are separable in the same way as stress relaxation behavior.
The tensile properties of polyethylene were measured with Instron tester at strain rates between 1.67 X 10^-4/sec and 3.33 X 10^-2/sec. The experimental equation of stress-strain curve agreed with eq. (2), except that the constants differed.
The fact that stress, like relaxation behavior, can be resolved into strain and time factors suggests non-linearity of both properties.

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Four factors are considered spinning conditions by which the breakage of yarn finished as the product is influenced. Cotton yarns differing in spinning conditions were produced and used to investigate the causes of yarn breakage. (1) The biggest cause for yarn breakage depends on how the ring size in spinning is fixed. The second biggest cause has to do with the number of travelers. In addition, the interactions, between the ring size and the number of travelers have significant influence on yarn breakage.
(2) The way in which yarn breakage occurs, yarn being thought of as a continuous body, has been investigated by using distance between peaks as a measure. This investigation has shown that the number of yarn breakages does not merely show a proportional relation to the mean yarn breakage. Instead, no matter whether breakages are fairly small in number or extremely large in number, weak points tend to show up locally.
This phenomenon is seen no matter what the spacing of rollers is on a loading tester, so long as there is a combination of the four factors mentioned above.

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This article discusses the relation between the selvage shape and the weft tension in the weaving process.
1) The conditions of the weft bobbin dimension and the shuttle tension devices to make the selvage line clear have been obtained experimentally.
2) The effective weft tension, which is closely related to the formation of the selvage shape, has been defined. The value of the effective weft tension and its position on the crank revolution have been clarified.
3) The concept of the effectvie weft tension can be extended to the warp. The effective tensions of warp and weft are different on the left-hand selvage and the right-hand selvage. As the result, it has been found that the handle side has advantages over the other side in regard to the selvage shape.

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The factors which influence selvage appearance have been evaluated and graded by fractional factorial experiments made at two levels.
The factors which improve the straightness of a selvage appearance are graded as follows:
1. The weft tension should be increased.
2. Variations in the warp tension should be reduced.
3. Weft tension variations should be reduced.
4. Tension of the selvage warp at the extreme edge should be strengthened.
The experiments have borne out what was said in instalments 1 to 3.

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