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Volume 53, Issue 5
Displaying 1-10 of 10 articles from this issue
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Yoshikazu HOSHIMURA1996 Volume 53 Issue 5 Pages 269-274
Published: May 25, 1996
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSA low density polyethylene resin (PE) sample degraded through partial discharge was investigated by pyrolysis gas chromatography (Py-GC). The evolved gas volume was found to increase with an increase in the degree of oxidative degradation. The results were correlated to the characteristic peak of carboxylic acids in the infrared spectra. In addition, carbon monoxide (CO) was detected as a pyrolysis gas from a degraded PE fiber of 80μm diameter by ozone oxidation. Moreover, the volume of the pyrolysis gas (CO) from the opaque PE treated with osmium tetraoxide was shown to be equivalent to that from the PE degraded by the discharge for 30 hours. These results suggest the Py-GC to be useful to evaluate the oxidative degradation of electrical insulating materials such as cables.View full abstractDownload PDF (1010K) -
Hiroyuki AIZAWA, Michiko TAZAKI, Terutake HOMMA1996 Volume 53 Issue 5 Pages 275-283
Published: May 25, 1996
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSPlasma polymerization to form thin films on substrates was carried out with three organosiloxanes (hexamethyldisiloxane, hexamethylcyclotrisiloxane, and octamethylcyclotetrasiloxane) and nitrogen-containing compounds (pyrrole, pyridine, and aniline) as monomers under the same conditions including reaction apparatus, input power, and monomer pressure. The structures of plasma polymers were discussed with FT-IR, and they were almost the same as those reported in the literature. Moreover, the initial formation process of the plasma thin films was observed with AFM, and there were clear differences in the initial stages of plasma polymerization depending on the monomer structures.View full abstractDownload PDF (10093K) -
Shigeki TAKAYAMA, Tsuyoshi ARAI, Masao KINOSHITA, Kunihiko TAKEDA1996 Volume 53 Issue 5 Pages 284-293
Published: May 25, 1996
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSFour major phenolic compounds: o-cresol, 2, 6-xylenol, 2, 4-xylenol, and 2, 4, 6-trimethylphenol were obtained as monomeric scission products by thermal degradation of poly (oxy-2, 6-dimethyl-1, 4-phenylene) (polyphenylene ether or PPE) in an inert atmosphere. The structures and contents of dimeric scission products recovered at the same time were more complicated than the monomeric products. The quantitative analyses of both scission products were used to elucidate the degradation mechanism. The chemical structures of the scission products suggested that the ether bridges in the main chain are partially converted to methylene bridges previous to the thermal degradation. The composition of the scission products can be explained by the assumption that the methylene bridges between benzene rings cleave almost in the same probability in spite of the circumstances. The structure of the polymer after heat treatment is much more relevant to the thermal degradation than that of the polymer before heat treatment.View full abstractDownload PDF (1731K) -
Michikage MATSUI, Yasuhiro MURASE, Shinji OHWAKI, Koichi IOHARA, Takea ...1996 Volume 53 Issue 5 Pages 294-301
Published: May 25, 1996
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSThe present study intends to explore the mechanism of the structure formation in the ultra-high speed spinning of poly (ethylene 2, 6-naphthalenedicarboxylate) (PEN) fiber. PEN fibers were spun with spinning speeds in the range from 5000 to 8000m/min, and characterized in terms of their physical properties, thermal properties, and fiber structure. The results were compared with the fiber spun at 5000m/min which had been studied in previous papers. The increase in spinning speed over 5000m/min resulted in the further development of molecular orientation, producing the PEN fiber with high tenacity, low elongation, and low shrinkage. The tenacity reached the maximum value of 0.92 GPa at 7000m/min. This value seems to be the highest obtained by a simple high speed spinning of commercially available polymers. However, the tenacity decreased where the spinning speed exceeded 7000m/min, probably due to the formation of a skin-core structure. The crystallinity estimated by the wide angle X-ray scattering was considerably higher than that calculated from density, which suggests that a tight para-crystalline structure is formed during spinning. The β-form crystalline structure became more stable at higher spinning speeds, and the crystalline transition from β-form to α-form took place only partly by annealing as-spun fibers. A necking deformation was observed on the spin-line, as in other polyester fibers. The refractional interference patterns around the neck suggest the formation of a skin-core structure.View full abstractDownload PDF (4294K) -
Yasuhisa NAGATA, Yuuki OHNISHI, Hiroaki HATORI, Minoru SHIRAISHI, Tisa ...1996 Volume 53 Issue 5 Pages 302-307
Published: May 25, 1996
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSNew carbon particles were prepared from highly crystalline polyimide ones treated at above 600°C. Such particles were obtained by heating polyamic acid solution as the result of thermal imidization of polyamic acids in N-methyl-2-pyrrolidone. The polyimide particles started to thermally decompose from about 500°C and almost finished being carbonized until 1000°C in a yield of 50%. The morphologies of obtained carbon particles were unique like a whisker or coral which had the particle size from 1μm to 5μm, judging from the observation of SEM, and such particles hardly changed at all from the morphology of precursor in spite of extreme decomposing and carbonizing processes. By the treatment at 2800°C, carbon particles from poly (p-phenylene pyromellitimide) were found to be almost graphitized. These had the interlayer spacing d002 of 3.39Å and crystallite thickness of 250Å. It was observed by TEM that the structure of particles like whiskers was made up by stacking of graphite layers, and those layers were turned and closed in a loop at the end of each particle.View full abstractDownload PDF (4680K) -
Hiroshi KUSANAGI, Kenji MATSUMURA1996 Volume 53 Issue 5 Pages 308-310
Published: May 25, 1996
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSNMR spectra of water molecules sorbed into polymers were measured by the 1H and 2H NMR procedures. The resonance peak width (Δν1/2) and spin-lattice relaxation time (T1) of 2H2O NMR spectra, which reflect the molecular motion of sorbed water, were found to vary according to the polymer chemical structures. Their variations originate from the differences in the heat (ΔE) of water sorption into polymers due to the polymer chemical structures.View full abstractDownload PDF (568K) -
Hiroshi KUSANAGI1996 Volume 53 Issue 5 Pages 311-316
Published: May 25, 1996
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSFor the copolymers of polyethylene (PE) with-13 mol% propylene (PP) components, the increase in the unit cell dimension of polyethylene crystal structure is observed by the X-ray diffraction method, but their crystal structures are not analyzed. These copolymer crystal structures were calculated by means of the packing energy minimization method. The variation in the unit cell dimensions observed by the X-ray method was reproduced in these calculations. It was, moreover, analyzed that the methyl group of the PP component does not destroy the crystal structure, but packs into crystal unit cell of PE.View full abstractDownload PDF (3272K) -
Masayuki IIJIMA, Sadayuki UKISHIMA, Yoshikazu TAKAHASHI1996 Volume 53 Issue 5 Pages 317-321
Published: May 25, 1996
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSWe discussed the film formation step in vapor deposition polymerization thermodynamically in this report. Enthalpy of vaporization of monomers (ΔH=10-30 kcal/mol) were measured from the plots of saturated vapor pressure as a function of reciprocal temperature. They were then compared with the activation energy (1-25 kcal/mol) between the monomers in solution. It is found that when the total enthalpy of vaporization of both the monomers is much larger than the activation energy, the polymers can be synthesized by the vapor deposition polymerization. Using this knowledge, an aromatic polyurethane and polyester were prepared for the first time by high temperature vapor deposition polymerization.View full abstractDownload PDF (841K) -
Muneki OHUCHI, Hiroharu HORIUCHI, Yoshirou SAKAI1996 Volume 53 Issue 5 Pages 322-329
Published: May 25, 1996
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSThe dynamics of counter-ion (lithium and sodium ions) and water molecule within several kinds of gel-type cation exchange resins of crosslinked poly (styrene sulfonic acid) has been investigated by NMR spectroscopy. The spin-lattice relaxation times of both ions in the ion exchanger were measured by 23Na and 7Li NMR, and activation energies of the correlation times of the ions were estimated. These ions relaxed faster within the resin than in aqueous solution, and with higher degree of crosslinking, i. e., crosslinkage. The diffusion coefficients of both counter-ions and water molecules in the resin were directly measured by 7 Li, 23Na, and 1 H NMR using a pulsed field-gradient method. These species diffused slower within the resin than in aqueous solution. The diffusion coefficients were affected by the crosslinkage: these values were smaller in a highly crosslinked resin. Apparent diffusion coefficients of Li+ ion and water molecules depended on diffusion times. These phenomena were explained by restricted diffusion in the three-dimensional network structure of the ion-exchange resin, gel-heteroporous type.View full abstractDownload PDF (1682K) -
Hiroshi KUSANAGI1996 Volume 53 Issue 5 Pages 330-332
Published: May 25, 1996
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSA Monte Carlo (MC) simulation program was derived for calculating thermal fluctuations in the molecular conformation of isotactic polypropylene (IPP); it was applied to the IPP model compound. The MC calculations gave reasonable results that an IPP oligomer chain forms a (3/1) helical conformation and a random coil at low and high temperatures, respectively.View full abstractDownload PDF (520K)
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