The purpose of this study is to increase the dispersibility of vapor grown carbon fiber (VGCF) filler in a polypropylene (PP) matrices. PP/VGCF composites were fabricated by a twin screw extruder. The effect of content, surface modification on the thermal conductivity, the electrical properties, and the mechanical properties of PP composites were investigated. These results indicated that thermal conductivity, the electrical properties, and the mechanical properties increased with the content of untreated VGCF and treated VGCF. PP composites showed a ductile failure in tensile testing, similar to untreated PP. In addition, untreated VGCF were non-uniformly dispersed and aggregated in PP composites. The aggregate sizes increased when increasing VGCF content. In contrast, treating VGCF surface with a titanate coupling agent had the effect of improving the dispersibility of VGCF in composites and adhesion between VGCF and PP matrix by reducing aggregate sizes and the distance between VGCF; these improved yield strength, Young’s modulus, and loss modulus. In addition, surface modification significantly improved the network structure of filler in composites, which led to increased thermal conductivity and decreased surface resistance at a high content of filler.

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So (Koto) is a traditional Japanese horizontal harp. Recently, for this music instrument, there are two types of strings made from silk and polyester filaments. The former is not only the strong points of tone and sound but also the weak point of durability and the latter has greater durability. In this research, we investigated how to produce novel silk so-string with good functionality. A composite so-string was designed with combining a silk so-string as core layer and a polyester filament yarn as sheath layer. And the durability and pleasant tone of composite so-string were examined. The following results were obtained: (1) the durability of the composite so-string was improved over 40 % in a comparison with the silk so-string; (2) The attenuation ratio of the composite so-string was better than that of the polyester so-string; (3) Additionally, the harmonic distribution of the composite string was nearly equal to that of the silk so-string.

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In this study, repeated compression-recovery behavior of fiber assembly for wadding use under high humidity condition is investigated, and its behavior is compared to that of standard condition. Sample used are twelve kinds of synthetic and regenerated fiber assembly. Following results are obtained. (1) Compression energy, WC under high humidity condition is smaller than that of standard condition or almost equal. (2) Recovery energy, WC’ under high humidity condition is almost equal to that of standard condition except CU-1 and RPE-4. WC’ of CU-1 and RPE-4 under high humidity condition is very small compared to standard condition. (3) Compression-recovery curve at sixth cycle is analyzed using linearizing method. In high humidity condition, n_B/n_F values of polyester fiber assembly are approximately 2, and those of cupra fiber assembly are approximately 3. Large value of n_B/n_F of cupra shows that cupra fiber assembly is less recoverable in compression than polyester under high humidity condition. (4) The result shows that evaluation of compression-recovery process using linearizing method is effective as well as that of energybased method using WC, RC and LC.

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