All issues
Successor
Volume 48, Issue 2
Displaying 1-13 of 13 articles from this issue
- |<
- <
- 1
- >
- >|
-
Keiji Kouzai, Kichiro Matsuda, Yutaka Tabe, Hisayuki Honda, Koh Mori1992 Volume 48 Issue 2 Pages 55-65
Published: February 10, 1992
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSThe wet spinning of poly-m-phenylene isophthalamide (PMIA)/N-methylpyrrolidone (NMP) solution with various coagulating medium was studied. The coagulation from the polymer solution in organic solvents or aqueous solution of NMP was caused by penetration of the coagulating medium into the polymer solution and resulted in the formation of voids in coagulated material. Therefore, no appropriate coagulating conditions could be realized. On the other hand, uniformly coagulated material could be obtained by the coagulation using highly concentrated, high-temperature aqueous solution of calcium chloride at short coagulation time, showing that the solution was one of the optimum coagulating mediums in wet spinning of PMIA/NMP solution. Amounts of calcium and chlorine remained in the coagulated film obtained in the coagulation bath containing high concentration of inorganic salt was steeply reduced, in contrast to the case of low concentration bath, which showed that reverse diffusion of coagulating medium was suppressed in highly-concentrated salt bath. The suppression was explained in terms of the hydration of salt.
Spinning experiments were performed using aqueous solutions of various inorganic salts as coagulation medium and a correlation between spinnability and state of hydration (estimated by vapor-pressure depression) was investigated. The spinnability was closely related to the extent of hydration of the salt, and excellent spinnability could be expected under conditions realizing sufficient hydration (at least 200 Torr vapor-pressure depression), independent of the kind of salt.View full abstractDownload PDF (3275K) -
Keiji Kouzai, Osamu Kai, Yutaka Tabe, Hiroshi Fujie, Kichiro Matsuda1992 Volume 48 Issue 2 Pages 66-73
Published: February 10, 1992
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSWet spinning of poly-m-phenylene isophthalamide (PMIA)/N-methylpyrrolidone (NMP) and PMIA/NMP containing calcium chloride was investigated using aqueous solutions of calcium chloride as coagulating medium. Void fractions, cross-sectional shapes and amounts of residual solvents in as-coagu-lated fibers were studied, and moisture contents in the fibers were estimated for the as-coagulated fibers obtained under wide range of conditions of salt concentration and temperature of the coagulation bath. Every spinning solution had a respective region of the optimum coagulating conditions in which uniformly coagulated fibers were obtained. In the case of spinning solution without salt, uniform as-coagulated fibers were obtained in the widest range of temperature at salt concentrations of 30-35%, and the region of optimum coagulating conditions was shifted to higher-temperature side and narrowed in the case of spinning solution containing salt. The as-coagulated fibers obtained in the region of optimum coagulating conditions were successively drawn in hot-water to give molecular pre-orientation and then drawn on a hot-plate (heat-treated) to afford PMIA fibers with high molecular orientation and crystallinity, The estimated moisture content in the as-coagulated fiber, used as a measure of reverse diffusion of coagulant during the coagulating process, depended upon the salt concentration in the coagulation bath. The moisture content in the as-coagulated fiber was estimated to be about 10% in the case of a coagulation bath with high-salt content of at least 30%. These results suggested that the reverse diffusion of coagulant into the spun fibers was suppressed in coagulation bath with high-salt concentration. On the other hand, the amount of residual solvent in the as-coagulated fiber strongly depended upon bath temperature rather than salt concentration in the range of 20-45% salt concentration and decreased with the rise in bath temperature. This result was attributed to the acceleration of the removal of solvent (normal diffusion) from the spun solution at higher temperatures.View full abstractDownload PDF (2298K) -
Masahiro Sano, Mitsuhiro Shibayama, Shinichi Sakurai, Hidenobu Kurokaw ...1992 Volume 48 Issue 2 Pages 74-83
Published: February 10, 1992
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSPoly (vinyl alcohol) (PVA) reacts with borate ions to give a thermoreversible gel. In this work, gel films (PVA-G) were successfully prepared by drying this gel or by soaking PVA films (PVA-O; crosslink-free PVA films) in a solution containing borate ions. On the other hand, the crosslinks formed in PVA-G can be removed by soaking PVA-G in an acid solution. The mechanical properties and structure of PVA-G were investigated by means of dynamic viscoelastic, wide angle X-ray diffraction, hot water resistance and thermogravimetric measurements, and were compared with those of PVA-O.
The results of dynamic viscoelastic measurements show that PVA-G retains a high value in storage modulus up to ca. 200°C which are different from PVA-O. In addition, there appeared a mechanical dispersion around ca. 220°C. Wide angle X-ray diffraction patterns show that the crystallite size of PVA-G is smaller than PVA-O. The characteristic behaviors in viscoelasticity are explained by the presence of crosslinks and/or crystallite size. Hot water resistance of PVA-G was also found to be improved by the introduction of crosslinks.View full abstractDownload PDF (682K) -
Tamako Toda, Hirohisa Yoshida, Mitsuhiko Hida1992 Volume 48 Issue 2 Pages 84-89
Published: February 10, 1992
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSThe effect of dye and water on the molecular motions of poly (ethylene terephthalate) (PET) was investigated by dynamic viscoelastic measurements and thermal analysis of dyed PET films. Both α and β loss modulus peaks of dry films shifted to lower temperature side with the increase of dye concentration, accompanied by a decrease of their apparent activation energy. The results suggested that dye molecules in the films enhanced the segmental mobility of PET as a result of plasticizing effect. The number of segments per unit cross section derived from the relaxation intensity of β dispersion, which was associated with local mode relaxation of PET. depended on dye concentration in the films. It is expected that higher dye concentration brings about a different mode of dye adsorption in PET substrates. The apparent activation energy of α dispersion due to glass transition of PET decreased markedly in the presence of water. The segmental mobility of PET chains seem to be much sensitive to moisture content in the film as compared with plasticizing effects by dye molecules.View full abstractDownload PDF (425K) -
Kazuhiko Fukatsu, Tomomi Takazono1992 Volume 48 Issue 2 Pages 90-95
Published: February 10, 1992
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSIn order to obtain some information regarding the degradation or morphological components of wool keratin fiber brought about by hydrogen peroxide under conditions in which the Cu (II) ion is bound to wool keratin the degradation of partly alkylated wool keratin fiber prepared by alkylating the generated sulfhydyl groups with 2-vinylpyridine was studied for the Cu (II)-partly alkylated wool keratin complex/hydrogen peroxide system. At the early stage of the degradation, peptide fragments in the treat. ment solution were found to contain a large amount of s-β-(2-pyridylethyl) cysteine residue and the tyrosine content in the wool fiber residue, which belongs in quantity to high-glycine-tyrosine proteins of an amorphous matrix, increased as the initial degradation proceeded. These results suggest that the high-sulfur proteins were easily degraded in the peptide bond cleavage of these proteins, which are contained especially in the cuticle.View full abstractDownload PDF (403K) -
Taeko Nakamura, Yasuko Sasaki, Tetsuya Sato, Kazushige Teraji1992 Volume 48 Issue 2 Pages 96-101
Published: February 10, 1992
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSIn order to study whether it is possible to express color images instrumentally, a color image scale for the determination of a chromaticity point by colorimetry was considered. The color image scale was divided into several color image regions by assigning the chromaticity point of each color chart to the color image of a color chart, on the color image scale. The chromaticity point and the color image can effectively be determined using the relationship between the chromaticity point and the color image in the color image scale.View full abstractDownload PDF (394K) -
HISANOBU WAKITA, HITOSHI OHTAKI1992 Volume 48 Issue 2 Pages P44-P49
Published: February 10, 1992
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSDownload PDF (1027K) -
HARUHIKO OHYA1992 Volume 48 Issue 2 Pages P50-P54
Published: February 10, 1992
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSDownload PDF (754K) -
TADAHIRO OHMI1992 Volume 48 Issue 2 Pages P55-P61
Published: February 10, 1992
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSDownload PDF (911K) -
SHOJI KUBOTA1992 Volume 48 Issue 2 Pages P62-P69
Published: February 10, 1992
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSDownload PDF (1058K) -
ATSUO KUMANO1992 Volume 48 Issue 2 Pages P70-P76
Published: February 10, 1992
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSDownload PDF (1119K) -
HISAYOSHI YAMAMORI1992 Volume 48 Issue 2 Pages P77-P82
Published: February 10, 1992
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSDownload PDF (944K) -
JAMES ERIC MCINTYRE1992 Volume 48 Issue 2 Pages P83-P88
Published: February 10, 1992
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSDownload PDF (921K)
- |<
- <
- 1
- >
- >|