抄録
In this paper we authors report the physical changes of vinylon-line netting cords caused by repeated heating. Samples used were Mewlon 2Oprime;S 3/9 (Upper twist: 56 and Lower twist: 130 for length 20cm), Kanebian 20prime;S 3/6 (Upper twist: 63 Lower twist: 136), and Cremona 18prime;S 3/6 (Upper twist: 54 Lower twist: 112). Besides these we adopted Cotton 20prime;S 3/6 (Upper twist: 98 Lower twist: 184) compared.
They were disposed in hot water (60°C) either 20, 30 or 40 minutes respectively after immersing in water rest of the 24 hours, then exposed in air and these procedure was repeated.
Tensile strength, elongation, diameter and length of these samples were all measured at the end of every exposure. From these experiments, the following results were obtained.
1) Any cord settles gradually to a constant final length and diameter (Fig. 1 and Fig. 2).
2) The ratio of shrinkage between disposed and non-disposed ones is greater in each vinylon-line netting cord as compared with the case of Cotton. In the former case the difference is especially greater in Mewlon and Cremona than in Kanebian.
3) The change of diameter is shown in Fig. 2, from which it can be seen that there exist the same differences between Mewlon, Cremona and Kanebian, Cotton.
4) From the above mentioned fact, it may be understood that Mewlon and Cremona are referable to one category and Kanebian to the other, although these are belonging to a same sort of vinylon-line.
5) Tensile strength and elongation of each vinylon-line netting cord decrease with the increase of repeated heating, but each of these dimensions will finally reach to a constant value. Variabilities of both tensile strength and elongation of each vinylon-line netting cord have a tendency to decrease as we saw, but vice versa in the case of Cotton (Fig. 5). This fact may presumably be due to the difference of mechanism between netting cord of vinylon-line and Cotton.
6) As seen in Figs. 1-5, effect of heating-time is not recognized.
