温延伸P. E. T.繊維の熱特性に関する研究
第1報 P. E. T.繊維の微細構造に及ぼす浴温の影響
1964 年 20 巻 6 号 p. 356-364
詳細
1964 年 20 巻 6 号 p. 356-364
In order to investigate the thermal properties of hot drawn P. E. T. fibers, the fine structures generated on hot drawing and heated at 170°C under a constant length, were determined by X-ray and optical polarized microscope. The drawing temperatures were selected over a range of 60_??_90°C in water and the fibers were stretched at a lower constant rate of drawing. Results obtained are shown as follows:
1) Transformation point of the relation between the draw ratio, density and birefringence of non-heated fibers may be found in the vicinity of draw ratio 2.0 in the case of a lower drawing temperatures (60 and 70°C), and their degree of crystallinity in the maximized and drawn fibers have only 20%. The values of the optical orientation factor (fr) become 0.60 and 0.24 respectively. The phenomenon of super-drawing is found in the case of drawing temperature, 80°C, and it may yet be extended beyond 650% extenstion, but the values of density are smaller as compared with non-drawn P. E. T. fiber and fr may be almost equal to zero. While effects of draw ratio on density are smaller in the case of drawing temperature, 90°C, their values of birefringence may be negative due to the crystallization occures in the immersion water and maximum value of fr becomes about -0.20.
2) The effects of draw ratio and temperature of drawing bath on density of heated P. E. T. fibers become smaller and the values of the degree of crystallinity are about 50_??_60%. On the other hand, their effects on birefringence are remarkable, that is, the birefringence at lower stretched specimens (draw ratio: 1.0 and 1.5) are negative and highly oriented specimens beyond 3.0 draw ratio develope strong positive birefringence, but the sign of birefringence at intermediate stretched (draw ratio: 2.0_??_3.0) changes from negative to positive with increased draw ratio. In both temperatures of drawing at 80 and 90°C, each stretched specimen shows a negative birefringence and it's value increase a littlle with increased draw ratio. And fr becomes negative in case of showing a negative birefringence, and then the average of orientation becomes greater than 54.6%
3) The X-ray diffraction patterns of non-heated and heated specimens do not have any intrinsic, difference except for specimens stretched at 90°C. The (100) reflection in X-ray patterns of heated specimens shows a peculiar behavior dependent on birefringence determinations, that is, the diffractive peaks of the (100) reflection is located in the meridian and equater on showing a negative and a strong positive birefringences, respectively. While its peak may be moved closer from the meridian to the equater in having a weak positive birefringence. On the other hand, the diffraction peaks of (010) reflection having any birefringence is located on the equater. Consequently, the orientation of crystallite are a-axis, c-axis and intermediate orientations respectively dependent of birefringence values. It is estimated that a-axis and c-axis oriented structures have folded and bundled crystallite respectively, but intermediate oriented structure has yet folded crystallite preferentially.
4) While intermediate oriented specimens show a strong positive value in degree of the heat-setting and consequently causes a spontaneous elongation due to the crystallization by heating, a-and c-axis oriented specimens show negative values in the degree of heat-setting followed by shrinkage.
