Poly(lactic acid). Группа авторов

from the melt are still ambiguous for these polyesters. Another important aspect of the biodegradable polyesters is related to the microscopically viewed investigation of their biodegradation process in the presence of bacteria. As described briefly about the phase transition of PHB, the role of taut tie chains passing through the stacked lamellae (or the rigid amorphous fraction, RAF) must be also revealed in association with the structure‐property relation of the bulk samples [72].

      In the long history of the biodegradable polyesters, many papers have reported their structural information. However, reliability of the crystal structure and chain conformation reported in the literature remain elusive. Different from the single crystals of low‐molecular‐weight compounds, the low accuracy of the analyzed structure might be fatal for the semicrystalline polymer substances because the poor X‐ray diffraction data of small and broad diffraction spots are collected at best. It is important to always check whether the structure information is consistent with other experimental data, as exemplified from several case studies presented in this chapter.

ACKNOWLEDGEMENTS

      The author Kohji Tashiro, is grateful for many researchers who collaborated and encouraged him in the structure studies of PLA: Dr. Hideto Tsuji (Toyohashi University of Technology, Japan), Dr. Takashi Ohhara (Japan Atomic Energy Agency), Dr. Nobuo Niimura (Ibaraki University, Japan), Dr. Tomoji Ozeki (Tokyo Institute of Technology, (present) Nihon University, Japan), Dr. Kaewkan Wasanasuk (Toyota Technological Institute, (present) PTT Public Co., Thailand), Dr. Makoto Hanesaka (Toyota Technological Institute), Dr. Tetsuo Kanamoto (Tokyo University of Science,), Mr. Naoto Kouno (Toyota Technological Institute), Dr. Jun Koshobu and Mr. Keisuke Watanabe (Japan Spectroscopic Co. Ltd., Japan), Dr. Suwabun Chirachanchai (Chulalongkorn University, Thailand), Dr. Piyawanee Jariyasakoolroj (Chulalongkorn University, (present) Kasetsart University, Thailand), Dr. Wannee Chinsirikul (National Metal and Materials Technology Center, Thailand), and Dr. Hiroko Yamamoto (Toyota Technological Institute, (present) Aichi Synchrotron Radiation Center).

      This work was supported by “the Strategic Project to Support the Formation of Research Base at Private University (2010–2014) and (2015–2019)” of MEXT, Japan, and also by the National Natural Science Foundation of China 22073015.

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