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Volume 1989 (1989)
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Volume 1989, Issue 140
Displaying 1-17 of 17 articles from this issue
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Hitoshi Nozaki, Masaya Kodama, Kunio Esumi, Kenjiro Meguro, Hidemasa H ...1989 Volume 1989 Issue 140 Pages 222-227
Published: December 05, 1989
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSFixation of ultra-fine platinum particles on meso-carbon microbeads was carried out. The fixation of the platinum particles with negatively charges was enhanced when the microbeads were treated with ammonia plasma due to electrical attraction forces between negatively charged platinum and positively charged microbeads in aqueous solution. Further, the magnitude of the fixation was dependent on the preparation method and heat-treatment temperature of microbeads.View full abstractDownload PDF (1915K) -
Kiyoshi Horita, Takao Fujita1989 Volume 1989 Issue 140 Pages 228-233
Published: December 05, 1989
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSThis experiment was carried out for the improvement of wettability of oxygen electrode with activated carbon. Adsorption isotherms of water and benzene on the two kinds of carbons which were charcoal and PVC char activated with ammonia gas at 950°C were determined to evaluate wettability and pore structure, respectively. It has been found that water adsorption isotherms for the activated carbons are typically S-shaped and that the micropore in these samples plays an important role on the adsorption of water. In the range of low relative pressure the amount of water adsorbed on the sample was proportional to relative pressure. The surface of the activated charcoal was more hydrophilic than that of the activated PVC char. Wettability of the activated carbons was dependent on the amount of surface oxides on these samples. The adsorption mechanism of water onto the activated carbon would be explained by using the cluster model and the condensation of water molecules.View full abstractDownload PDF (808K) -
Kazuhiro Fujiki, Norio Tsubokawa, Yasuo Sone1989 Volume 1989 Issue 140 Pages 234-240
Published: December 05, 1989
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSThe effect of e-value of vinyl monomers on the radical graft polymerization initiated by azo or peroxyester groups introduced onto carbon black surface was investigated. In the presence of carbon black having azo-groups (CB-Azo), the polymerization of vinyl monomers with positive e-value, such as methyl methacrylate, was initiated to give polymer-grafted carbon black. Although the polymerization of vinyl monomers with negative e-value, such as styrene, initiated by CB-Azo was retarded, the corresponding polymer was also grafted onto the surface. On the other hand, carbon black having peroxyester groups (CB-POE) was capable of initiating the polymerization of vinyl monomers with positive e-value, but incapable of that with negative e-value. Therefore, vinyl polymers with negative e-value were unable to graft onto carbon black by use of CB-POE. A similar tendency was observed in the polymerization initiated by 4, 4'-azobis (4-cyanopentanoic acid) or t-butyl peroxybenzoate, as a model compound of initiating groups on the carbon black surface, in the presence of untreated carbon black: the polymerization of styrene initiated by t-butyl peroxybenzoate was remarkably retarded by carbon black. These results indicate that the radical graft polymerization initiated by initiating groups introduced onto carbon black surface is affected by e-value of vinyl monomers.View full abstractDownload PDF (885K) -
T. Furuta, Y. Yamashita, M. Shiraishi1989 Volume 1989 Issue 140 Pages 241-247
Published: December 05, 1989
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSThe microtextures of carbons reacted at 900°C with CO2 gas were studied to obtain a basic information on a relation between reactivity and structure of the carbons. A porous non-graphitizable PF sample has higher reactivity, while a typical lamellar graphitizable carbon, Ku, shows lower reactivity of about 60% for that of PF. The reaction rates of carbons heat-treated at 2800°C were about 40% of those heat-treated at 1200°C.
It is found from TEM observation that the oxidation of PF sample proceeds homogeneously in microscopic range. The carbon surface became remarkably rough with development of pores by the oxidation, and altered to a lean and more open microtexture with pore diameters from several to 200 nm. It is observed for Kusample that the edge planes react more faster than the basal planes. As the reaction of the carbon with CO2 gas proceeds, elliptical pores between the layer stacks appeared and the ordering of layer stacking decreased to a short range and then disappeared completely to form the porous microtexture of lean nonstacked layers as seen in PF sample reacted severely. It is presumed that Ku sample shows such a high reactivity as PF sample if entirely transformed from the anisotropic to the porous isotropic microtexture.View full abstractDownload PDF (6817K) -
Yoshihiro Sawada, Yoichiro Nakanishi1989 Volume 1989 Issue 140 Pages 248-254
Published: December 05, 1989
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSThe factors that determine stress transfer capacity at carbon fiber/thermosetting resin interface are studied.
High strength and high modulus types of PAN-based carbon fibers with or without surface treatment were used. The surface treated fibers were heated in hydrogen at 750°C to change the surface characteristics. The interfacial shear strength between the carbon fibers and resin matrices was determined by an embedded single filament tensile test method. The surface roughness of carbon fiber was quantitatively estimated from BET surface area by krypton adsorption and geometric surface area of the optical diameter. The surface chemical activity was characterized by oxygen chemisorption and ESCA spectra.
The regression analysis was performed on obtained data in order to estimate those contributions to the interfacial shear strength. It was shown that the chemical interaction plays major role in determining the interfacial shear strength. Within the increment of interfacial shear strength of the high modulus type fiber by surface treatment, the contribution of the mechanical anchoring is below 44.8%. But on the high strength type fiber, it is less than 13.0%. This difference due to fiber types was provided an explanation with the defference in the structure of the fiber sheath.View full abstractDownload PDF (1069K) -
Effect of Surface Morphology of Carbon FibersL. M MANOCHA, O. P BAHL, Y. K SINGH1989 Volume 1989 Issue 140 Pages 255-260
Published: December 05, 1989
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSCarbon/carbon composites have been made with three kinds of carbon fibers having irregular shape, bean shape and circular crossections as reinforcements and coal tar pitch as matrix precursor with low pressure pyrolysis. The microstructure of the matrix at the fiber/matrix interface is found to be influenced by the surface morphology of the fibers. This is further found to influence the fracture behaviour and mechanical properties of the ultimate carbon/carbon composites.View full abstractDownload PDF (2824K) -
Akira Kojima, Sugio Otani, Norihiro Hayashi, Takeo Ohte1989 Volume 1989 Issue 140 Pages 261-267
Published: December 05, 1989
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSSurface modification of pitch based high modulus carbon fiber (CF) by cold plasma was investigated to give high compativility between CF and matrix in CF/resin composites (CFRP) and CF/carbon composites (C/C). The surface treatment of CF filament was carried out with O2 plasma generated by radio frequency (13.56 MHz). The CF surface was analyzed by ESCA. It was found that the acidic group on the CF surface was formed by O2 plasma. The unidirectinally CFRP plates (4 mm in thickness) were prepared by orientating CF prepreg coated with phenolic resin, and carbonizing at 1000°C under nitrogen.
These CFRP and C/C plates showed the bulk density of 1.7 g/cm3 and the CF contents of 60-70vol%. The fractured behavior and mechanical strength of CFRP and C/C plates were changed with input power of O2 plasma. The flexural strength and compressive strtength of CFRP and C/C plates prepared from CF filament treated in O2 plasma at 50 W with input power, Was the largest of all.
The cold O2 plasma treatment for CF is recommended as an ingenious method for the surface modification of CF.View full abstractDownload PDF (2505K) -
Takeo Ohte, Masaaki Katoh, Sugio Ohtani, Akira Kojima1989 Volume 1989 Issue 140 Pages 268-274
Published: December 05, 1989
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSThe surface modification of glassy carbon (GC) by radio-frequency (13.56 MHz) discharge plasma was investigated to obtain the surface modification mechanism. The GC surface became remarkably hydrophilic by argon cold plasma. The relation between the surface characteristic (the wettability of water) of GC and the plasma condition was estimated experimentally. Furthermore, the GC surface was observed by SEM. From these results, the following facts were found.
The contact angle of water on GC was reduced from 90° to 15° by the argon discharge plasma treatment with the input power of 50 W for 60 sec. in setting GC on the powered electrode. The GC surface was etched remarkably in this treatment. The water wettability on the GC surface increased as the ion density or the energy of the plasma increased. The contact angle of water on GC increased from 15°to 52° in air at the room temperature for 24 hours or increased in O2, though it was almost constant under the vacuum condition.These facts suggest that the formation of the active radical as well as the hydrophilic group would give rise to the decrease of the contact angle of water on GC by the argon plasma treatment.View full abstractDownload PDF (2591K) -
Shinzo Nomura, Tamotsu Saito, Hisashi Imai1989 Volume 1989 Issue 140 Pages 275-281
Published: December 05, 1989
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSKinetic mechanism of air oxidation was studied for PAN T-300 carbon fiber in a temperature range from 500 to 600°C. Rates of the oxidation for the fiber can be described as the following auto-catalytic rate equation: dα/dt=kα (1-α) Arrehenius plot of the rate constant, k, gave single straight line and the activation energy for the oxidation was estimated to be-22.7 kcal/mol. The energy was a half of that reported for Celion 6000 graphitized carbon fiber. A homogeneous shrinkage oxidation mechanism did not meet either with the oxidation rate behavior or the fiber radius change with burn-off. SEM observation and laser Raman spectroscopy for the oxidized fibers also supported the auto-catalytic oxidation mechanism.View full abstractDownload PDF (2730K) -
Jiro Takei, Sugio Otani, Akira Kojima1989 Volume 1989 Issue 140 Pages 282-287
Published: December 05, 1989
Released on J-STAGE: March 01, 2011
JOURNAL FREE ACCESSThe deposition of low temperature pyrolytic carbon (LTPC) on the substrate constituted by winding the carbon paper around core rod of Ti alloy created the strong bonding between the core and the carbon paper layer.
By scanning electron micrography and micro X-ray diffraction technique, it was confirmed that the intermediate layer containing Ti3AlC, Ti2N and TiO was formed between the core and carbon paper layer.
In the course of chemical vapor deposition (CVD), cis-1, 2-dichloroethylene decomposed into carbonaceous fragments and HC1 vapor, and then TiCl4 and AlCl3 were produced by the reaction of the HCl vapor with the core alloy. In the results, themixed gas of the carbonaceous fragments, the metal chlorides, N2 as carrier gas and O2 as impurity were retained in the carbon paper layer. It seems that the intermediate layer deposited from the mixed gas.View full abstractDownload PDF (4220K) -
Katsumi Kaneko, Takaomi Suzuki, Kazunori Kakei1989 Volume 1989 Issue 140 Pages 288-295
Published: December 05, 1989
Released on J-STAGE: March 01, 2011
JOURNAL FREE ACCESSCellulose-, polyacrylonitrile-, and pitch-based activated carbon fibers (ACFs) were partially oxidized at 373-1173 K for 1 h in air. The detailed N2 adsorption isotherms of 60-100 points for these partially oxidized ACFs were statically measured by use of a computer controlled gravimetric apparatus. The adsorption isotherms were analyzed by the Dubinin-Radushkevich plots and it was confirmed that N2 molecules are filled by the multi-stage micropore filling mechanism (MSMF) proposed in the preceding paper. The changes in the micropore size distribution and the average micropore width of ACF were evaluated by applying the MSMF mechanism; in the case of pitch-based ACFs, the average micropore width increases from 0.85 to 1.20 nm with the change of oxidation temperature from 373 to 1173 K.View full abstractDownload PDF (979K) -
Akio Shindo1989 Volume 1989 Issue 140 Pages 296-305
Published: December 05, 1989
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSSurface structural elements, surface properties and adhesion to resins are reviewed on PAN-based carbon fibers. The surface active carbon atom concentration of carbon fibers without surface treatment decreases with increasing fiber young's modulus. The increases in specific surface area and active surface area rate by surface treatment are observed on commercial carbon fibers. The surface roughness, defined using the BET area and the geometric surface area, of every carbon fiber is higher at a higher degassing temperature than that at a lower degassing temperature. The surface treatment by anodic oxidation technique leaves decomposition product, lowering adhesion to the resin, on the carbon fiber surface in an acidic solution, but not in alkaline solution. There is a linear relationship between the active surface area rate and the surface oxygen concentration for every type of carbon fiber produced by every manufacturer. The interfacial shear strength in carbon fiber-resin systems depends greatly on the active surface area rate and/or the surface roughness.View full abstractDownload PDF (2657K) -
Masamitsu Oshikiri, Tetsuro Yokono, Yuzo Sanada1989 Volume 1989 Issue 140 Pages 306-309
Published: December 05, 1989
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSThe change in extent of generation of radicals during the early stage of carbonization in A240 pitch with addition of carbon black treated by oxygen plasma was investigated by means of high temperature ESR. The increase of radical concentration of pitch with addition of plasma treated carbon black is explained by the reduction in transferable hydrogen to stabilize the free radicals created in pitch. This is caused by the abstraction of transferable hydrogen by the oxygenated functional groups on the surface of plasma treated carbon black.View full abstractDownload PDF (434K) -
Eiichi Yasuda, Yasuhiro Tanabe, Minoru Takabatake1989 Volume 1989 Issue 140 Pages 310-313
Published: December 05, 1989
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSMatrix microstructure in carbon fiber/carbon composite of pitch derived carbon could be changed into fine structure using graphite fine powder (1 μm under) added carbon fiber on it. The matrix in the composite changed into fine mosaic structure, and the bending strength of the composite increased compared with that of composite with fibers having no-graphite particles.View full abstractDownload PDF (4412K) -
Yoshiyuki Nishiyama, Naonori Sonehara1989 Volume 1989 Issue 140 Pages 314-316
Published: December 05, 1989
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSAn activated carbon was heated in hydrogen at 900°C for 4h and theni mpregnated with nickel nitrate from an aqueous solution to prepare carbon -supported nickel catalyst. The activity of the catalyst was compared with a catalyst supported on untreated activated carbon for hydrogenation of benzene at 85-120°C and hydrogenolysis of ethane at 280-350°C. The activity of nickel was greatly increased by the pretreatment of the support: 3 times in the hydrogenation of benzene to cyclohexane and about 30 times in the ethane hydrogenolysis to form methane. The dispersion of nickel on the supports was measured using temperature programmed desorption of hydrogen as well as X-ray diffraction technique. The large increase in the activity is attributed to the increased dispersion of nickel on the pretreated carbon surface, possibly due to the elimination of hetero-atoms.View full abstractDownload PDF (355K) -
Kouichi Yasuda, Takeshi Yazawa, Yohtaro Matsuo, Shiushichi Kimura, Mik ...1989 Volume 1989 Issue 140 Pages 317-321
Published: December 05, 1989
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSA new method for fabrication of carbon/Si3N4 composites was examined. Carbon/Si3N4 composites were prepared from mixtures of liquid polysilazane and filler cokes by pressureless sintering at 1400°C. Carbon/Si3N4 composites showed the bulk density of 1.76g/cm3, the bending strength of 75 MPa, and the good resistance against oxidation. The good resistance against oxidation of these composites was supposed to be caused by thin shell structures of Si3N4 which surrounded filler cokes. This characteristic structure resulted from using liquid polysilazane.View full abstractDownload PDF (3785K) -
Norio Tsubokawa, Takeshi Endo1989 Volume 1989 Issue 140 Pages 322-336
Published: December 05, 1989
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSTo modify chemically the surface of carbon materials, such as carbon black, graphite powder, carbon fiber, and carbon whisker (vapor-growth carbon fiber), the incorporation of functional groups onto these surface was reviewed.
Carbon materials having reactive groups such as acyl chloride, acyl azide, and active ester groups can be used for the grafting of hydroxyl- or amino-capped commercial available polymers. The grafting method by the reaction of reactive groups on carbon material with polymers enables us to control the molecular weight of grafted polymer chain.
The incorporation of initiating groups such as azo, peroxyester, acylium perchlorate, and potassium carboxylate groups, onto carbon surface could be succeeded and their applications to the graft polymerization and copolymerization of various monomers were attempted to obtain polymer-grafted carbon blacks with a higher percentage of grafting.
Furthermore, it was demonstrated that carbon materials, especially carbon black having much oxygen containing groups, acted as not only curing agent of urethaneprepolymer, epoxy resins, and polyfunctional spiro ortho ester resins but also electron transfer catalyst of two-phase systems (aqueous-organic phase) in dehydrogenation of hydrazo nitriles.View full abstractDownload PDF (1779K)
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