Mitsumasa Matsushita

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.

A New Material Recycling Technology for Automobile Rubber Waste

A new material recycling technology for crosslinked rubber was developed using the continuous reactive processing method. In this process of producing reclaimed rubber, breakage of crosslinking points in the crosslinked rubber occurs selectively under the controls of shear stress, reaction temperature, and internal pressure in a modular screw type reactor. Deodorization during the process has also become possible by a newly developed method. The reclaimed rubber obtained from rubber waste generated from both automobile manufacturing products and post-consumer products shows excellent mechanical properties applicable to new rubber compounds. Furthermore, an enhanced rubber recycling process for producing thermoplastic elastomer (TPE) based on rubber waste has been established. The obtained TPE exhibits highly recoverable rubber elasticity and mechanical properties comparable to commercial TPE. It is expected that the rubber recycling technology developed and presented in this study will contribute to protecting the environment and also saving of resources. (A) For the covering abstract see ITRD E121867.

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.