This article discusses the propagating velocity of longitudinal pulse wave in polyethylene film varying according to stretching directions.
Assume a tape cut along the machine direction to be an x-cut and a tape cut along the transferse direction a y-cut. Then the following results are obtainable:
(1) The propagating velocity of longitudinal pulse wave of an x-cut tape is low whether the tape is nonstretched, x-stretched, or y-stretched.
(2) The propagating velocity of longitudinal pulse wave of a y-cut tape is low, whether the tape is not stretched or x-stretched, but it is high, about 3000(m/sec), when y-stretched.
(3) The orientation of the crystalline regions inspected by X-ray diffraction shows that the c-axis of the crystalline regions has a normal distribution with four peaks slightly inclined to the normal of the film and that the a axis has a normal distribution with two peaks in two directions slightly deviating from the width direction.
(4) The potential energy of Van der Waals is φ(R)=1/2∑<Ω>(-8.703×10^-58/R⁶ -6.540×10^-102/R¹²)(R cm) where ∑<Ω> is the sum total of all the specimens.
(5) From the potential energy of Van der Waals, the velocity of longitudinal pulse wave v, and the elastic coefficient E are calculable as follows: In the a direction, v_a 3420(m/sec) and E_a 1.176 10¹¹(dyn/cm²). In the b direction, v_b 6280 (m/sec) and E_b 3.995 10¹¹(dyn/cm²). Assuming the distance between the neighboring chains in amorphous regions to be 5.00-5.20A, v_am is 760-1460(m/sec), E_am is 0.68-3.4 10¹⁰(dyn/cm²) and the density is 0.794 0.888(g/cm³).
(6) The average distance R between the neighboring chains, is calculated from the strength distribution of X ray diffraction. R-5.20A.

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A new method to measure the flexural rigidity of fabrics is discussed here. It treats a fabric as an elastica. The two ends of a specimen, 2L long, are clamped vertically 2X apart. The edge of a knife compresses the center of the specimen placed on the cross head of an Instron-type tensile tester. When the distance between the knife edge and the plane that includes the clamped ends of the specimen equals X, compressing force P' is measured. In the case of L=2.0cm and X=0.5cm, flexural rigidity D of the specimen is expressible as follows: D=0.071×P'g•cm²
A specimen measured by this method is nearly equal in rigidity to one measured by the cantilever method, and the shape of a deformed specimen fits that of a calculated elastica.

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An experiment was made to make the experimental weft-inserting equipment referred to in Part 1 serviceable. The experiment was aimed at continuous running of this equipment and weaving by it-and was conducted by attaching it to a conventional loom run at high speed.
The results of the experiment raised a question. How are the flying orbit of the carrier and the carrier speed influenced by weft tension, air resistance and acceleration of gravity? An equation on the carrier speed was deduced theoretically to analyse the influencing factors.

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The bearing which the geometric construction of the fabrics has on the reflective intensity curve has been investigated. The probe has shown experimentally that the reflective property varies with the curved structure of yarns. The reflective intensity curve has been theoretically deduced by assuming that a fabric is composed of yarns having tiny facets.
Reflective light flux ρ_φ at incidence angle α and view angle φ is: Ρ_φ=kT_α+φ/2cosα+φ/2•σ(α-φ/2) where T_α+φ/2 is the specular reflectance of the tiny facets if the angle of incidence perpendicular to the facet is a α+φ/2; σ is a function expressing the density distribution of the tiny facets; and k is a constant.
Applying this theoretical formula to the elliptic curvature has revealed various reflective properties for various degrees of curvature and shown that the yarn curvature has a major bearing on the reflective property of fabrics.

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