Influences of Twisting, Heat Setting and Untwisting of Polyethylene Terephthalate Filament Yarns on Fiber Structure.:Part 1 : Single Monofilament Yarn
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概要
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The change in fine structure of polyethylene terephthalate (PET) yarns textured by the false-twisting process was studied. For simplicity, the monofilament yarn of PET, the diameter of which was about 0.6 mm, was used instead of multifilament yarns in this study. The false-twisting process was divided into two stages, i.e., (i) twisting and heat setting stage and (ii) untwisting stage. The changes in fine structure in each stage were investigated by wide-and small-angle X-ray diffraction methods and the measurements of densities and melting points.<BR>In the twisting and heat setting stages, the degree of orientation of the molecular chain in the crystalline region gradually decreases with increasing the number of twists. It changes steeply especially in the region of more than 200 tpm. The angle between the fibril and the fiber axis agrees well with the twist angle of the filament calculated based on the model. The crystallinity, the crystallite size as well as the structure of long period unit are scarecely affected. While the lattice distortion within the crystallites increases with increasing the number of twists.<BR>In the untwisting stage, the direction of fibrils almost recovers accompanying the recovery of crystal orienation in the twist region of less than 133 tpm. In the region of more than 200 tpm, however, the crystal orientation partially recovers and the value of the orientation factor remains at the lower values than that of th untreated sample. Thechanges of the crystallite size and the structure of long period unit are not appreciable even in this stage. The minute crystallites with large lattice distortion, formed in the twisting and heat setting stages, are destroyed resulting in the slight decrease of crystallinity.
- 社団法人 日本繊維機械学会の論文