An experimental study for isotropic pitch materials prepared from cracking oil residues has been carried out to clarify the Theological properties in the molten state. The softening point, thermal expansion coefficient, viscosity and the viscoelastic moduli were measured. The aromatization index of the isotropic pitches was estimated from the element analysis (C and H), density, and the NMR measurements. The activation energy for shear flow which was estimated from the temperature dependence (100°C to 150°C) of the steady shear viscosity was 40 kcal/mol. The softening points, thermal expansion coefficient and the activation energy were correlated to the aromatization index. The steady state shear viscosity was described to be proportional to the molecular weight with the 40th power. The frequency dependences of the dynamic moduli were similar to those of monodisperse linear polymers.

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Carbonaceous gel was prepared from the alkaline solution dissolving amphiphilic carbonaceous material. Gelation of the amphiphilic carbonaceous materials dependedon concentration of the amphipihlic carbonaceous material and the alkaline solution. This so-called carbonaceous gel showed a reversible transformation between sol and gel with temperature. That is, this gel has a quasi-stable structure like agar.
Moreover, a carbonaceous dry gel was prepared by drying the carbonaceous gel. This carbonaceous dry gel gave a different thermal behavior from that of the original amphiphilic carbonaceous material.
Carbonaceous gel beads were prepared by a new method termed “water in oil emulsion method” using the alkaline aqueous solutions dissolving the amphiphilic carbonaceous materials. These beads had spherical shape and smooth surface. However, the surface morphology and area of the beads were changed by heat-treatment. Especially, by heat-treatment at 900°C the gel beads prepared from aqueous solution of potassium hydroxide became rough surface and had over 400 times larger surface area than as-prepared.

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A temary molybdenum chloride-chloroform-graphite intercalation compound (MoCl₅-CHCl₃-GIC) was synthesized in chloroform solution at room temperature. The identity period along c-axis of the GIC obtained was 1.94 nm, corresponding to that of the stage 4 structure of the binary compounds synthesized by mixingmethod. The temary MoCl₅-CHCl₃-GIC decomposed below 200°C, much lower than the binary MoCl₅-GIC, and exfoliated even at 400°C. The remakable exfoliation behavior of temary MoCl₅-CHCl₃-GIC was due to the existence of CHCl₃ molecule in the graphite gallery with MoCl₅.

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Coal-tar pitch was spun into fiber by melt-blowing method. Nozzles to feed pitch and hot airwere arranged concentrically in the die of the spinning apparatus. It was found that the size of diameter of the pitch fiber was strongly influenced by feed rates of pitch and hot air through the die, operating temperature and the diameter of the pitch nozzle, thinner fiber being obtained by applyinghigher operating temperature. The upper limit of spinnable temperature yarned according to the diameter of capillary of the pitch nozzle, smaller diameter of 0.2mm ∅ of the capillary being ableto apply higher temperature. At the optimum operating conditions using 0.2mm∅ capillary, pitch fiberhaving a diameter of 8μm was obtained at pitch-feed rate of 0.167g/min·hole. These results maybe superior to take-up roller spinning.

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An electrical conduction model for highly-disordered carbon is developed to account for the fractional temperature dependence of the conductivity. It is assumed that the conduction consists of many independent Arrhenius-type processes with various activation energies and the density of these Arrhenius processes has a A-shape distribution as a function of activation energy. Then the proposed model can reproduce the conductivity behavior which has been widely observed for disordered systems.
Phenol-based activated carbon fibers, as a representative highly-disordered system, are used for conductivity measurements to check the validity of the proposed model. The activated carbon fibers are heat treated in Ar to control the degree of structural disorder. As an index for the degree of disorder, the activation energy for conduction is estimated by the model. The results show that the activation energy, which was -25meV before heat treatment, decreases by heat treatment and an insulator→metal transition takes place between HTT=1000-1200°C Of importance is that the fractional temperature dependence, which has been ascribed to Mott's variable range hopping or the Coulomb interaction model, can also be derived by the presented mechanism.

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Change (mainly contracting) of bulk size along the c-axis of halogen-graphite intercalation compounds (GICs) was measured from room temperature to 385K using dilatometer with a diffrential transducer.
The value of dL/L of IC1-GIC (stage 1) showed successive decrease according to increase of temperature and sudden stepwise decreases at 304K and 320K, corresponding to the stage transition temperatures. The IC1-GIC (nearly stage 5) after 2nd run exhibited a expansion peak with positive temperature derivative at 314K.
On the other hand, the Br-GIC (stage 2) didn't indicate so-called “exfoliation” at about 373K. This fact was caused by the very low heating rate in this study.

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Electric resistance of heaters made of isotropic graphite, IG-11, was measured in the temperature range from room temperature to 3000°C in argon atmosphere. Four heaters with different sizes were set in four furnaces, being installed with different capacities of electric sources 1900A×10.5V, 2700A×20V and 3500A×24V. The increase of resistance with temperature rise from about 1000°C to 3000°C was observed for the heaters whose applied voltage was 10V, whereas remarkable decrease of resistance above 2500°C appeared for two other heaters applied 12V. It was found that the temperature dependence of electric resistance of graphite heater is influenced by not only graphite material and gas atmosphere but also the matching between heater size and capacity of power source.

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More than ten years in Japan the technology development has been carried out by some companies, that is, Nippon Steel, Nippon Oil, Mitsubishi Kasei, etc. for high performance of mesophase pitch-based carbon fiber. Now, new manufacturing processes have been established which produce carbon fibers of, for example, high tensile strength, 3.8 to 4.0 GPa.
In the present review, the manufacturing method and approach to high performance, fiber microscopic structure and properties of those newly developed in Nippon Steel, along with material property evaluation for application and future prospects for the fibers will be discussed.

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