Title of Research:
19_D08-01 Elucidation of the formation mechanism of microplastics
Principal Investigator:
Kuroda Shinichi (Graduate School of Science and Engineering, Gunma University)
29-1 Honmachi, Ota City, Gunma Prefecture 373-0057(tel) 0276-50-2434 (e-mail) skuroda@gunma-u.ac .jp
Collaborators:
Kouzai Hiroaki (Department of Science and Engineering, Kanto Gakuin University), Kuriyama
Takashi (Graduate School of Organic Materials and Systems Science, Yamagata University)
Ohtani Hajime (Graduate School of Engineering, Nagoya Institute of Technology), Igarashi Toshio(Research Division for Science and Technology, Kanazawa University), Hiejima Yusuke (ResearchDivision for Science and Technology, Kanazawa University), Tokumitsu Katsuhisa (Materials
Science Division, Faculty of Engineering, University of Shiga Prefecture) , Kawai Takahiko(Graduate School of Science and Engineering, Gunma University)
Summary of Research:
The purpose of this study is to clarify the mechanisms by which secondary microplastics aregenerated from plastic products from the viewpoints of polymer science and polymer engineering.
The study focused on analyzing microplastics (MP) in the environment and elucidating themechanism of the miniaturization of the MP in the environment.
The use of deactivated SiO2 as a diluent was effective in Py-APGC-MS measurements for
pyrolysis analysis of plastics. An algorithm for analyzing MP in the environment was developedand its usefulness for analyzing unknown marine plastic samples was demonstrated.
Next, MP shapes recovered in the estuary were divided into pellets and flake fragments, withpellets recovered in greater numbers than flakes. In addition, crack patterns were observed in 13%
of all PP pellets. Most of the spherical pellets showed an isotropic crackle pattern, indicating thatthese pellets were manufactured by hot cutting. In contrast, about 30% of the flakes developed
parallel crack patterns, indicating the influence of molecular orientation during flow molding. Inorder to evaluate the mechanical collapsibility of the pellets, ball milling tests using glass beads
were conducted, and it was found that the collapsibility can be evaluated by the actual MP surface
degradation layer peeling off due to mechanical action.
Finally, a diamond disk grinder was installed and rotated in the flow path of the high-speed
swirling airflow of the conventional jet mill system to increase the efficiency of accelerated MPformation. The PS elastomer was successfully milled to a fine particle size of approximately 5 μmin diameter using this improved jet mill system. It is expected that this improved jet mill can beused to grind any type of plastic into fine particles of a few microns in diameter, and is expected tobe used as a standard MP for biotoxicity evaluation.
Timeline: March 2021-.
Topics:Online presentation "Elucidation of the mechanism of microplastic formation" at the 2021LRI
Research Report Meeting
Publications: Presentations: (Only the PI's presentation)
1) Shinichi Kuroda, "Accelerated Production of Micro- and Nanoplastics Using Impact Pulverization", Academic
Symposium on Marine Plastic Litter, March 3, 2021 (online)
2) Shinichi Kuroda, "Issues and Research Trends on Microplastics", Suga Weathering Webinar
2021, December 1, 2021 (online)