The effects of convolutions on mechanical properties of cotton fibers treated with vapor-phase (VP) -formaldehyde (HCHO) were studied . Cotton was pretreated to remove the convolutions in three different fiber assembly states, namely, fiber, yarn, and fabric. The samples were further treated with the liquid ammonia (L. NH₃), NaOHaq., and NaOHaq. /L. NH₃. It was found that (1) the microscopic and structural changes are closely related with the tenacity retention of cotton, and (2) the tenacity retention increases with an increase in the X-ray orientation degree. The tenacity retention of fibers and yarns is larger than that of fabrics at the same X-ray orientation degree and bound HCHO level. The effects of extension and orientation of amorphous regions in cotton fibers on the tenacity retention before and after VP-HCHO-finishing were examined from the S-Scurves of ramie fibers untreated and treated with water, and the relaxation times (T_1c) of cotton fibers untreated and treated with water using CP/MAS ¹³C-NMR, respectively. The results indicate that the tenacity retention of cotton fibers before and after VP-HCHO-finishing is closely related with the extension and orientation of amorphous regions of cotton fibers. The relation between X-ray orientation degree under load and stress of cotton and ramie fibers before and after VP-HCHO-finishing was also discussed.

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In an air jet loom, compressed air is used for the weft insertion. In order to produce the compressed air, much electric power is necessary. To reduce the energy, an accelerating apparatus of the weft yarn (PDC-system) has been developed and the efficiency of the apparatus was assessed in the previous work. It was found that the energy for the weft insertion could be reduced by using the apparatus.
For this apparatus being used in various air jet looms, the flight state of the weft yarn should be analyzed in detail. In this work, the effects of PDC working conditions on the tip velocity of weft yarn and the weft yarn tension are investigated. From the investigations, it is found that the flight state of the weft yarn is more easily controlled by using the accelerating apparatus of the weft yarn.

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One of the methods to examine quality under production of the synthetic yarn and running condition of the equipment is to measure the winding up tension. However, the tension meter commercially available has the defect to dedect the yarn quality as its sensor comes in contact with the yarn.
In the previous report, we analyzed movement of the synthetic yarn caused by the motion of the traverse guide. We reported that the tension was able to be calculated by measuring the propagation speed of the bending wave of the yarn.
In the present paper, we report on the technique and device to achieve non-contact measurement of tension.
The results obtained are as follows :
(1) The measurement value of non-contact tension meter developed in this study is corresponding well by a conventional contact type tension meter in relative evaluation.
Therefore, non-contact tension meter has accuracy equal with the contact type tension meter.
(2) The indication revel of the contact type tension meter is smaller than that of the non-contact type by (Line density) x (Running velocity of yarn) ², as the former detectrr has the characteristic structurally to take in count the centrifugal force exerted to the yarn bent at the detection guide as equivalent reduced tension though the centrifugal force doesn't affect to the yarn tension at all.
(3) The sensing system is developed to measure the propagation speed of the bending wave of the yarn eliminating the influence of the changes in passing point of the wave across the sensing beam, applying the sudden change property of the reflection angle of beam before and after the pass the sharp wave top generated by sudden reversing of the traverse guide. And so we put non-contact tension meter to practical use.

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