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Volume 50, Issue 7
Displaying 1-12 of 12 articles from this issue
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Tetsuya Takahashi, Atsuo Konda, Yoshio Shimizu1994 Volume 50 Issue 7 Pages 241-247
Published: July 10, 1994
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSMixed spinning and drawing of polypropylene/polyamide 6 (hereafter “PP/PA6”) were carried out with a melt spinning machine for monofilament. The relationship between the blending ratio of components and the creep characteristics of the fiber was mainly investigated. Creep deformation of the blend fiber containing more than 60% of PA6 was equal to that of PA6 fiber, The “critical creep stress”, increased with the increase of the content of PA6. The increase was larger particularly in the content range from 40 to 60%. The primary yield stress in the stress-strain curve (hereafter “S-S curve”) increased with the increase of the content of PA6 and decreases with the decrease of straining rate. The “critical creep stress” corresponded to the primary yield stress at the lower strain rate. It was considered, therefore, that the creep deformation depended upon the properties of the matrix constituent of fiber.
Thus, the creep characteristics of the blend fiber can be explained fairly well with the S-S curve. The blend fiber has the stable structure in a region below the primary yield strain and it is plastically deformed above the primary yield strain, whereupon the structure may be recomposed.View full abstractDownload PDF (410K) -
Tetsuya Takahashi, Atsuo Konda, Yoshio Shimizu1994 Volume 50 Issue 7 Pages 248-255
Published: July 10, 1994
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSThe relationship between mixing state and dye-affinity of polypropylene/polyamide 6 (hereafter “PP/PA6”) blend fiber was investigated by examining the crystallization behavior. The peak corresponding to the crystallization of PA6 in the DSC curve obtained by cooling the melted blend fiber depended upon the content of PA6, the melt viscosity ratio of both components (η PP/η PA6), and the existence of the compatibilizing agent. Any crystalline peak was hardly observed in a DSC curve of a sample containing PA6 of 40% or less and showing the melt viscosity ratio of 0.4 or less. The heat of crystallization of PA6 correlated with the content of PA6 in the surface layer of fiber determined from the infrared absorbance spectrum. The behavior of the heat of crystallization depended upon the dispersion state of both components. It was considered, therefore, that the peak corresponding to the crystallization of PA6 was low for the blend fiber composed of better dispersed components, because the crystallization of PA6 was hindered by the melted PP. The dye molecules were hardly diffused and PA6 was hardly bled to the surface layer in these fibers. In the blend fiber composed of the phase-separated components, however, it was considered that the dye molecules were relatively easily diffused and the content of PA6 in the surface layer of fiber was relatively high in the samples in which the crystallization of PA6 was hardly hindered. No peak due to PA6 crystallites was observed in the wide-angle X-ray diffraction pattern of a sample exhibiting no crystallization peak of PA6.
Thus, the dye-affinity of the fiber depended upon the dispersion state of both components, and could be improved by controlling the dispersion of both components.View full abstractDownload PDF (625K) -
Hiroshi Tsugita, Fumiyoshi Yokoyama, Yuhiko Yamashita1994 Volume 50 Issue 7 Pages 256-262
Published: July 10, 1994
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSPoly(p-oxycinnamyl) (POC) crystals were obtained by polyesterification of 4-acetoxy cinnamic acid under elimination of acetic acid in aromatic solvent, Therm-S900. Morphology and structure of the crystals were studied by scanning electron microscopy, transmission electron microscopy and wide-angle X-ray powder diffractometry. Conformational simulation of POC was also made. The crystals were obtained as mixture of spherical, rod-like, and lamellar morphologies. The existing ratio of the morphologies depended on the preparation conditions, temperature, concentration, and time. The rod-like crystals were only observed in the limited preparation conditions, 280-290°C and 1.0-2.0 wt%. With increasing temperature and concentration, the spherical crystals became predominant. Based on the results, it was assumed that this polymerization system was characterized by two mechanisms: one is related to the formation of spherical crystals which were obtained from molten oligomer droplets formed by the phase separation, and the other is related to the formation of crystals with the other shapes as rods and lamellae from solution. It was revealed that the crystal system of POC prepared at 1.5 wt% of monomer and 280°C was orthorhombic with a=0.82nm and b=0.48nm.View full abstractDownload PDF (2207K) -
Masahiro Yoshinobu, Mitsuhiro Morita, Mitsuo Higuchi, Isao Sakata1994 Volume 50 Issue 7 Pages 263-268
Published: July 10, 1994
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSThe partially hydrolyzed graft copolymers of crosslinked polyacrylamide (PAM) on water-soluble hydro-xyethylcelluloses(HECs) with different molecular chain lengths were synthesized by using of the ceric ion in-itiation method in an aqueous medium, and the effect of the molecular chain length of the HEC trunk polymer on the swelling behavior of the graft copolymer (HEC-AM-Hyd) was investigated. The synthesized HEC-AM-Hyds were similar to one another in the proportion of the HEC trunk polymer and the grafted branch polymer and in the crosslinking density and content of carboxyl groups of the partially hydrolyzed PAM branch polymer. The absorbency of HEC-AM-Hyd increased with an increase in the molecular cahin length of the HEC trunk polymer. The HEC-AM-Hyd from the HEC with longer chain length had higher resistibility against the decrease in the absorbency with an increase in the NaCl concentration than that from the HEC with shorter chain length. It is con-sidered that the HEC molecule that has high rigidity and extends largely in water acts effectively in the swelling of HEC-AM-Hyd, and that the superior swelling properties of the HEC-AM-Hyd from the HEC with longer chain length are due to the larger extension of its trunk polymer.View full abstractDownload PDF (417K) -
Eiko Nakayama, Ken Sasaki, Natsuko Kohara, Harukazu Toyoda1994 Volume 50 Issue 7 Pages 269-273
Published: July 10, 1994
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSA series of cyanoethylated pullulan (CEP) with various degrees of substitution (DS) were prepared homogeneously, by the addition of a Na/DMSO solution and acrylonitrile to a dimethyl sulfoxide (DMSO) solution of pullulan. The DSs of CEP thus prepared were in the range from 0.045 to 2.89. The CEP with high DSs were soluble not only in dimethylformamide and DMSO, but also in cyclohexanone and acetone. Thermal decomposition temperatures were constant irrespective of the DS. These behavious of the CEPs prepared by the present method were different from those prepared in the presence of water by a conventional method. This suggests that these differences are due to the differences in molecular orientation and distribution of cyanoethyl groups.View full abstractDownload PDF (321K) -
Akifumi Nishikawa, Hiroyuki Makara, Nobuko Shimasaki1994 Volume 50 Issue 7 Pages 274-281
Published: July 10, 1994
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSSilk fibroin membranes and polyethylene films have been fluorinated by CF4 (tetra-fluoromethane) lowtemperature plasma on conditions that CF4 gas flow rate was 30mL/min, treatment time was 2 minutes, and discharge power variation was 30_??_400W, followed by being immersed inpure water. Fluorine atom in their samples before and after extraction test, and fluoride ion in the extracted water were quantitatively analyzed. Surface component of their samples before and after extraction was also analyzed by XPS. As a result, fluorine containing groups being soluble in water were formed only by the fluorination of silk fibroin membranes. The effect of the surface structrure change of fluorinated silk fibroin membranes on the water swelling ability, the water contact angle and the dyeability were examined. As a result, the hydrophobicity and the water contact angle increased, and the water swelling ability decreased with increasing of the fluorine fixation content. After extraction, decreasing of the water contact angle was found, which suggested hydrolysis of fluoride acid end groups (-COF). Moreover, the primary amino group formation by the decomposition of peptide bonds was also suggested and it was supposed that this amino group caused the increase of the dyeability by acid colors.View full abstractDownload PDF (568K) -
Masanori Kyo, Takao Kashiwagi, Toyofumi Kato, Yoshinobu Kamata1994 Volume 50 Issue 7 Pages 282-289
Published: July 10, 1994
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSIt was tested whether several kinds of neoprene and syntactic foam materials currently available could be effective as thermal insulators used in the deep-sea up to 6500m depth. The density and thermal conductivity of the materials after pressurized repeatedly with various pressure, and the bulk modulus of them were measured under atmospheric pressure, The experimental data obtained thus derived the heat flow through the materials under high hydrostatic pressure. Based on the data, the tested materials were evaluated on the ability as deep-sea thermal insulators, to suggest that the syntactic foam is more excellent than the neoprene foam in pressure-as well as in thermal-proof and, though, the latter might be also effective for thermal-proof since it can almost recover the original volume when it is floated up to the shallow water.View full abstractDownload PDF (1314K) -
Yoshitomi Morikawa, Atsuo Shibuya, Yukino Koizumi1994 Volume 50 Issue 7 Pages 290-297
Published: July 10, 1994
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSA technique using a CCD camera system is proposed for measuring simultaneously the local displacements at many points on a deformed fabric in the tensile process without contacting with the sample. The local displacements can be transformed into local plane strains and a characteristic angle representing the global deformation. The distribution of strains on the fabric surface is characterized by the average and width of distribution of the local strains. The technique was applied to a few kinds of polyester fabrics and verified to be an effective means for clarifying quantitatively the distribution of local strains on fabrics extensively deformed.View full abstractDownload PDF (1092K) -
Mi-Seon Chu, Toyofumi Kato, Yoshinobu Kamata, Toshinari Nakajima1994 Volume 50 Issue 7 Pages 298-305
Published: July 10, 1994
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSThe clothing microclimate, i.e., the climate within the narrow space between a human body and the clothes, was investigated being focused on the thickness effect of the space for the case where the internal air was ventilated only through the openings of the clothes. A manikin dressed in a shirt made of a material impermeable to the air was used in the experiment and the air flow in the clothing space was detected by an oxygen trace gas technique. The ventilation behavior was simulated by a two-dimensional simplified model and analyzed by a finite difference method. For case in which ventilation was done solely by diffusion, the calculated results agreed well with the experimental ones. If accompanied by convection, the ventilation got greater efficiency depending strongly on the flow rate. Increasing the thickness of the air layer varied the clothing microclimate significantly when it was under about 1cm, but hardly did when above it.View full abstractDownload PDF (575K) -
Atsushi Suzuki1994 Volume 50 Issue 7 Pages 306-313
Published: July 10, 1994
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSThe clinging of a fabric covering a human body to the skin was simulated by an idealized plane model for the case of the very beginning of perspiration. The model assumes that the opposite surfaces of the skin and covering are two parallel planes having different wettability and the sweat (water) existing between them forms a cylinder whose free surface makes a meniscus of a constant curvature which is determined by the surface tension of water. The clinging force between the planes and the degree of wetting on each were evaluated for various combinations of the wettability of surface, the amount of sweat, and the spacing between the planes. The analysis clarified a possible reason which may elucidate why a man feels a cotton covering is more comfortable than a polyester one when he perspires slightly.View full abstractDownload PDF (539K) -
Satoko Tanaka, Kazuyoshi Seguchi1994 Volume 50 Issue 7 Pages 314-320
Published: July 10, 1994
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSThe oxidative decomposition of seven water-soluble dyes with sodium hypochlorite at 20°C under various pHs was investigated in the presence and absence of surfactants, such as sodium dodecylbenzenesulfonate (DBS), sodium dodecylsulfate (SDS), hexadecyltrimethylammonium bromide (CTAB), and polyoxyethylene (23) dodecyl ether (B-35). On the basis of pH-profiles of the apparent decomposition-rate constants of the dyes obtained from their half-life periods, the dyes were classified into two categories in the absence of surfactants. The origin was inferred mainly from oxidation mechanism of functional groups (amino or hydroxyl group) in the dyes. The effects of surfactants on the decomposition-rate were also investigated for typical two dyes, which showed contractive pH-profiles. As results, the cationic CTAB over the cmc enhanced oxidative decomposition remarkably, and on the contrary, the anionic DBS and SDS micelles and the non-ionic B-35 micelle rather slightly retarded the decomposition. These phenomena were interpreted in terms both of binding of the dyes with the micelle due to ionic interactions, and of solubilization of oxidation species (ClO_??_, HOCl, and Cl2) into the micelles. The measurements of partition coefficient of sodium hypochlorite to organic and water layers at 20°C supported the enhanced decomposition mechanism for the cationic micelle.View full abstractDownload PDF (558K) -
Hiromi Gocho, Toshinari Nakajima1994 Volume 50 Issue 7 Pages 321-324
Published: July 10, 1994
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSIn order to elucidate the effect of the cuticle on the sorption behavior of wool fibers, the sorption of water vapor on Merino and chemically descaled wool fibers was measured with the weighing bottle and quartz spiralbalance methods. The equilibrium water uptake was higher for Merino wool than that for the modified one. This difference was ascribed to the decrease in the amount of polar groups in the modified wool. At the initial stages of water sorption, the sorption capacity of the modified wool was higher than that of Merino wool. The relationship between the water uptake and the square root of the sorption time showed that epicuticle and exocuticle layers of Merino wool acted as barriers for the water vapor penetration.View full abstractDownload PDF (272K)
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