成形加工
Online ISSN : 1883-7417
Print ISSN : 0915-4027
ISSN-L : 0915-4027
12 巻, 11 号
選択された号の論文の21件中1~21を表示しています
目次
巻頭言
解説
講座
技術報告
日本の大学・試験・研究機関の研究 : 89
会議・見本市だより
製品・技術紹介
論文
  • 占部 宏生, 伊藤 浩志, 鞠谷 雄士, 奥居 徳昌
    2000 年 12 巻 11 号 p. 729-735
    発行日: 2000/11/20
    公開日: 2009/11/18
    ジャーナル フリー
    In order to clarify the mechanisms of molecular orientation in high-speed melt spinning of polypropylene (PP), the change of birefringence along the spinline was analyzed through the simultaneous on-line measurement of the diameter and optical retardation profiles. The optical retardation was evaluated using an optical system with a rotating polarizer, polarizing filters, quarter-wave plates and a He-Ne laser as the light source. The birefringence increased only slightly in the upstream portion of the spinline. On the other hand, there was a steep increase of birefringence, which became more significant with an increase in the take-up velocity, near the solidification point where crystallization appears to start. An additional increase of birefringence was notably observed in the downstream portion of the spinline where the thinning of the spinline was already completed. The as-spun PP fibers also showed a gradual increase of birefringence even after the spinning, indicating that the increase of birefringence after the solidification of the spinline was caused by the change in the super-structure of the fibers, not by the increase in tensile stress along the spinline because of the accumulation of the air-friction force. To analyze the applicability of the stress-optical law, tension and temperature profiles of the spinline were calculated based on the experimental results of the diameter profiles. The small increase of birefringence in the molten state was found to be due to the low stress-optical coefficient of PP. It was also found that at take-up velocities above 1km/min the steep increase of birefringence started at the position where the tensile stress of the spinline exceeded about 1MPa. These results suggest that the orientation-induced crystallization of the PP spinline starts at this stress level and also that the development of birefringence of PP fibers in the high-speed spinning process is significantly affected by the crystallization.
  • 佐野村 幸夫
    2000 年 12 巻 11 号 p. 736-741
    発行日: 2000/11/20
    公開日: 2009/11/18
    ジャーナル フリー
    The dependence of the mechanical behavior of an amorphous polymer on processing conditions was experimentally investigated. Hot rods of polycarbonate were extruded and cooled rapidly under constraint of strain recovery. Rods were extruded at elevated temperature close to the glass transition temperature. Uniaxial tensile tests and shear tests were made at room temperature. The stress-strain curves were affected by extrusion processing conditions, such as extrusion ratio, extrusion temperature and constraint of strain recovery. The Young's modulus, tensile strength and shear strength of extrudates below the glass transition temperature increased with increasing extrusion ratio. The mechanical properties of extrudates under free strain recovery were smaller than that under constraint of strain recovery at the same extrusion ratio. Since marked strain recovery appeared in products under free strain recovery, products with high extrusion ratio could not be obtained with increasing extrusion temperature and extrusion rate. The mechanical properties of extrudates above the glass transition temperature hardly depended upon the extrusion ratio and the degree of strain recovery. A high degree of molecular orientation was exhibited by polycarbonate extruded at high extrusion ratio below the glass transition temperature under constraint of strain recovery. The mechanical properties of extrudates followed a linear trend with increasing birefringence. The stress-strain curve of a cold drawn sample was almost coincident with that of an extrudate at the same drawing ratio.
  • 志熊 治雄, 小山 清人
    2000 年 12 巻 11 号 p. 742-746
    発行日: 2000/11/20
    公開日: 2009/11/18
    ジャーナル フリー
    The viscoelastic properties of column-fractionated alpha-olefin copolymers made by metallocene catalysts were studied. The Effects of long chain branching on the rheological properties were investigated for fractions obtained from two types whole polymers which were produced using different catalysts. Fractions including polymer chains with long branches have long relaxation times. It was found that the long branching causes strong effects such as the molecular weight dependence on zero-shear viscosity.
    The Damping function of polymer fractions is similar to that of the unfractionaled polymer from stress relaxation experiments.
学位取得者の紹介
feedback
Top