Yoshihide Katagiri

A novel morphological model for carbon nanotube/polymer composites having high thermal conductivity and electrical insulation

Carbon nanotubes (CNTs), owing to their extremely high thermal conductivity (∼3000 W m−1 K−1), have recently attracted attention as notable nanofiller candidates to improve the thermal conductivity of polymers. However, CNTs cannot practically be used for highly electrically insulating polymers because even a few CNTs impart a high electrical conductivity to the polymers. Here, we design and fabricate CNT/polymer composites having a novel morphology, which achieves both enhanced thermal conductivity and high electrical insulation. This morphology comprises a matrix polymer and a CNT-localizing domain polymer encapsulated by a shell-forming component, which contributes to the selective localization of the CNTs into the dispersed domains. Such a controlled morphology is formed by the self-organization of the CNTs and the constituent polymers. A tailor-made morphology of CNT/polymer composite in accordance with our proposed model represents a promising route to a wide variety of applications of CNTs in materials requiring high electrical insulation.

Super impact absorbing bio-alloys from inedible plants

Injection molded bio-alloys based on polyamide 11 (PA11), 100% bio-based plastics from inedible plants, and polypropylene (PP) mixed with the maleic anhydride-modified ethylene-butene rubber copolymer (m-EBR) were prepared using a twin-screw extruder. The mechanical properties and morphologies of the bio-alloys were investigated using flexural tests, Charpy notched impact tests, field emission-scanning electron microscopy (FE-SEM), Raman spectroscopy, and transmission electron microscopy (TEM). The bio-alloy had a flexural modulus of 1090 ± 20 MPa and a Charpy notched impact strength of 98 ± 5 kJ m−2, which is superior to that of polycarbonates. The FE-SEM observations revealed that the bio-alloy has a unique “salami-like structure in a co-continuous phase”, and the TEM observations showed that some m-EBR formed 10 to 20 nm wide continuous interphases between the PP and PA11 matrices. Continuous rubber interphases played an important role in enhancing the impact strength. The bio-alloys exhibited good rigidity and excellent impact strength, making them feasible for applications in automobiles and other industries.