Yosuke Nishitani

By Yosuke Nishitani, Chiharu Ishii and Takeshi Kitano

Part of the book: Polypropylene

By Yosuke Nishitani, Toshiyuki Yamanaka, Tetsuto Kajiyama and Takeshi Kitano

To further enhance the mechanical, thermal, and tribological properties of short natural fiber-reinforced biopolymer composites, it is very critical to understand thermal properties of these biomass composites and their dynamic viscoelastic properties in the molten state. The aim of this study is to experimentally investigate the thermal properties of hemp fiber filled plant-derived polyamide 1010 composites and their dynamic viscoelastic properties in the molten state. It was found that the addition of HF with PA1010 has a strong influence on the thermal properties such as DMA, TGA, and DSC. HF is very effective for improving the thermal and mechanical properties. The effect of alkali treatment on the dynamic viscoelastic properties of the HF/PA1010 composites in the molten state differs according to whether alkali treatment uses silane coupling agent or not. The viscoelastic properties of NaClO2 are higher than those of NaOH. Silane coupling agents have a remarkable influence on rheological properties such as storage modulus, loss modulus, and complex viscosity in the low angular frequency region in the molten state, temperature dependences of rheological properties, and relationship between the phase angle and complex modulus. These rheological behaviors are also strongly influenced by the type of silane coupling agents.

Part of the book: Viscoelastic and Viscoplastic Materials

By Yosuke Nishitani and Takeshi Kitano

For the purpose of developing new engineering materials with sufficient balance among mechanical, electrical, processability, triboloical properties, etc., in this study, we investigated the dynamic viscoelastic properties of carbon nanofiber (CNF) filled polyamide (PA) composites and the blend of these composites and thermoplastic elastomer (TPE) in the molten state, which were mainly obtained in our previous studies. It was found that vapor grown carbon fiber (vapor grown carbon fiber) has a stronger influence on the dynamic viscoelastic properties of the composites in the molten state. Rheological percolation thresholds seem to exist between 1vol.% and 5vol.% of VGCF contents. On the other hand, the effect of the addition of TPE (styrene-ethylene/butylene-styrene copolymer (SEBS) and maleic anhydride grafted SEBS (SEBS-g-MA)) on the dynamic viscoelastic properties of VGCF/PA6 composites in the molten state differed at each viscoelastic value. It was clarified that the dynamic viscoelastic properties of VGCF/PA6/SEBS-g-MA ternary composites are higher than those of VGCF/PA6/SEBS ones. Furthermore, the influence of processing sequences on the dynamic viscoelastic properties of VGCF/PA6/SEBS-g-MA composites in the molten state differed according to the mixing steps of materials. These may be attributed to the change in the internal structure caused by addition of TPE, type of SEBS and processing sequences.

Part of the book: Viscoelastic and Viscoplastic Materials