Thermal conductivity of low density polyethylene (LDPE) filled with carbon black (CB) was measured as a function of CB fraction. The thermal conductivity increases with increasing the weight fraction of CB. The particle size and the dispersion state of CB also affected the thermal conductivity. In order to study the thermal conductivity at high CB fraction, liquid paraffin (LPA) was used instead of LDPE. The thermal conductivity of the complex of CB and LPA exhibited a maximum value at the CB weight fraction of 0.5. The increase of the thermal conductivity with the CB weight fraction came from the filling effect of the CB, and the decrease came from mixing of air. In order to interpret these experimental facts, three-layers model consisting of CB, PE and air was proposed. The results calculated from the model agreed well with the exprimental results.

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The heat absorption by polymer films continuously irradiated with an incandescent lamp was investigated by measuring rates of change in temperature and the equilibrium temperature of the film for bare and backed films. The presence of infrared active groups in the structural units, the film thickness and the degree of crystallinity contributed to the increase in the equilibrium temperature and the rate of temperature rise. This increase was greater for backed films. Polyethylene films containing a small amount of carbon black had much greater capacity for absorbing thermic rays and attained higher equilibrium temperatures.

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The structure of carbon fibers from polyoxadiazole (POD) was investigated in relation with preparation conditions of starting POD fibers. Two types of POD were synthesized from a hydrazine and terephthalic acid system and a hydrazine, terephthalic acid and isophthalic acid system, and were spun to fibers by wet spinning. The wet spun POD fibers were then pyrolyzed at 1300 and 2800°C. With increase in draw ratio of starting POD fibers, the carbon layer stacks of resulting carbon fibers increased their sizes and orientation. Carbon fibers showed a turbostratic layer structure at the stage of heat-treatment at 1300°C. By heat-treatment at 2800°C, the structure of the carbon fibers from drawn POD fibers changed to that with three-dimentional order. A coaxial-lamellar texture was represented in the cross-section of carbon fibers heat-treated at 2800°C. No marked difference attributable to the difference in chemical composition between the starting polymers was observed for the structure of carbon fibers.

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Biodegradation of pitch-based isotropic graphite fibers, made by heat-treatment at 2000°C. by microorganisms was studied. Microbe strains (Aspergillus flavus and Aspergillus sojae) were incubated on Czapek agar slant medium, deficient of carbon source, at 30°C in the presence of graphite fibers. The biodegraded fiber was examined by scanning electron microscopy. Breaking area on the surface of the fiber (length in the direction of fiber axis, 24μm) was biodegraded for 30 days by A. flavus. An adhesive matter at the breaking area on the surface of the biodegraded fiber was observed. The degree of biodegradation of the fiber was evaluated from the length of the biodegraded area along the fiber axis. The minimum area of biodegradation in the initial stage of degradation was 2μm in length or smaller. Biodegradation of the fiber began at the point of random orientation of graphite structure on the surface layer of the fiber, progressed to the enlargement in volume of the restricted area in the layer and to the breaking of the restricted area. The central part of the fiber did not seem to be biodegraded, because no fiber was observed to have been completely degraded. A term of “pinhole degradation” was proposed for this type of degradation of pitch-based isotropic graphite fiber by microorganisms.

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Properties of fibers at low temperature has scarcely been reported because of the experimental difficulties. With an interest in the properties of textile fibers under the extremely cold conditions, tensile strength, knot strength, tearing strength and hardness of various yarns and fabrics were measured with instruments placed in the room under the condition of +20°C to -50°C. The phenomenon of cold brittleness of the textile fibers could not be found under the extremely cold condition, the strengths of silk, nylon, vinylon, polyester fibers increased but that of acrylic fiber decreased. Generally, the elongation of fiber decreased while the strength increased. Mechanical troubles of the moving parts of the instruments should be taken into accounts because they could be frozen at low temperature.

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Hydrogels were prepared from oxidized wood meals and chemical pulps by phosphorylation with phosphoric acid and urea. A transparent hydrogel, which was prepared from wood meals by oxidation with chlorite followed by phosphorylation, was capable of absorbing 115gH₂O/g sample. As oxidant, peracetic acid and ozone were also applicable to the pretreatment. Colored gels were obtained from phosphorylated kraft and sulfite pulps. The water absorbency of phosphorylated kraft pulp was 66gH₂O/g, while that of phosphorylated sulfite pulp was 29gH₂O/g. Wood meals phosphorylated without oxidation and the chemical pulps absorbed only several times each weight of water. These results indicate that the pretreatment with chlorite is the most effective for the hydrogelation.

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