Molecular insight into toughening induced by core-shell structure formation in starch-blended bioplastic composites

Akihiro Yamaguchi; Satoshi Arai; Noriyoshi Arai

doi:10.1016/j.carbpol.2023.120974

Molecular insight into toughening induced by core-shell structure formation in starch-blended bioplastic composites

Carbohydr Polym. 2023 Sep 1:315:120974. doi: 10.1016/j.carbpol.2023.120974. Epub 2023 May 5.

Authors

Akihiro Yamaguchi¹, Satoshi Arai², Noriyoshi Arai³

Affiliations

¹ Circular Industries Research Department, Production Engineering and MONOZUKURI Innovation Center, Research and Development Group, Hitachi, Ltd., 2-9-2, Yoshida, Totsuka, Yokohama, Kanagawa 244-0817, Japan; Department of Mechanical Engineering, Keio University, 3-14-1, Hiyoshi, Kohoku, Yokohama, Kanagawa 223-8522, Japan. Electronic address: akihiro.yamaguchi.jb@hitachi.com.
² Material and Solution Department, Supply Chain Resilience Division, Hitachi High-Tech Corp., 1-17-1, Toranomon, Minato, Tokyo 105-6409, Japan. Electronic address: satoshi.arai.ze@hitachi-hightech.com.
³ Department of Mechanical Engineering, Keio University, 3-14-1, Hiyoshi, Kohoku, Yokohama, Kanagawa 223-8522, Japan. Electronic address: arai@mech.keio.ac.jp.

PMID: 37230615
DOI: 10.1016/j.carbpol.2023.120974

Abstract

Binary and ternary blends with poly(lactic acid) (PLA), poly(butylene succinate) (PBS), and thermoplastic starch (TPS) were prepared by a melt process to produce biodegradable biomass plastics with both economical and good mechanical properties. The mechanical and structural properties of each blend were evaluated. Molecular dynamics (MD) simulations were also conducted to examine the mechanisms underlying the mechanical and structural properties. PLA/PBS/TPS blends showed improved mechanical properties compared with PLA/TPS blends. The PLA/PBS/TPS blends with a TPS ratio of 25-40 wt% showed higher impact strength than PLA/PBS blends. Morphology observations showed that in the PLA/PBS/TPS blends, a structure similar to that of core-shell particles with TPS as the embedding phase and PBS as the coating phase was formed, and that the trends in morphology and impact strength changes were consistent. The MD simulations suggested that PBS and TPS tightly adhered to each other in a stable structure at a specific intermolecular distance. From these results, it is clear that PLA/PBS/TPS blends are toughened by the formation of a core-shell structure in which the TPS core and the PBS shell adhered well together and stress concentration and energy absorption occurred in the vicinity of the core-shell structure.

Keywords: Core-shell structure; Molecular dynamics (MD) simulations; Poly(butylene succinate) (PBS); Poly(lactic acid) (PLA); Thermoplastic starch (TPS); Toughening mechanism.