| 高分子 Vol.70 No.1 |
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特集 海洋環境と高分子
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| 展望 COVER STORY: Highlight Reviews |
| マイクロプラスチックによる海洋汚染 ～海洋科学と高分子科学の担う役割～ Oceanic Pollution Caused by Microplastics |
磯辺 篤彦 Atsuhiko ISOBE |
| ＜要旨＞ 海洋における浮遊マイクロプラスチック分布の実態と将来予測について、また想定される環境影響について、海洋科学と周辺分野の得た知見を紹介するとともに、今後の高分子科学分野との連携を呼びかける。 Keywords: Ocean Plastics / Microplastics |
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| 高分子科学から見たマイクロプラスチック Importance of Fundamental Polymer Science of Microplastics |
高原 淳 Atsushi TAKAHARA |
| ＜要旨＞ 高分子の使用量が増えるにつれ、環境に廃棄物が流出して生成したマイクロプラスチック（MP）が社会的な問題になっている。本稿では海洋で採取されたMPの特性解析、その結果に基づくMP生成のモデル実験、さらには今後必要不可欠となるMPの基礎研究について解説する。 Keywords: Microplastic / Polyolefin / Degradation / Photooxidation / Fragmentation / Analytical Methods/ Separation |
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| マイクロプラスチックとプラスチックリサイクル Microplastics and Polymer Recycle |
府川 伊三郎・井出 陽一郎 Isaburo FUKAWA, Youichiro IDE |
| ＜要旨＞ 海洋プラスチック（マイクロプラスチック）問題がグローバルな環境問題として注目され、これがトリガーとなってプラスチック資源循環問題に発展した（第1章、第2章 府川執筆）。 その対策として、リサイクルが注目されている。廃プラからポリエチレンボトルを再生するリサイクルの取り組みを紹介する（第3章 井出執筆）。 Keywords: Ocean Plastics / Microplastics / Circular Economy / Mechanical Recycle / Chemical Recycle / Single Use Plastics / PE / PP |
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| トピックス COVER STORY: Topics and Products |
| 消失した海洋マイクロプラスチックの謎 －水存在下でのポリプロピレンの微細化機構－ A Puzzle of Lost Marine Microplastic: Fragmentation Mechanism of Polypropylene in Water |
中谷 久之 Hisayuki NAKATANI |
| ＜要旨＞ A polypropylene (PP) film photodegradation test was performed in water with a specific photocatalyst under visible light irradiation to identify its fragmentation mechanism. The results showed that the surface exfoliation was provoked by the test. The spherulite structure contributed to the surface microcrack location and growth. The microcrack allowed entrance of water into the inner amorphous part. The water caused an internal stress by expanding itself due to radiant heat from the visible light irradiation and induced a microcraze in the interlamellar amorphous region. The microcraze developed into an internal microcrack, and surface microcracks finally coalesced together, producing a planar exfoliation. The weight change ratio and rate of the photodegraded PP film showed multi-stages with the increase of photodegradation time. The increment of positive rate was small, showing that the exfoliation caused suppression of the autoxidation rate. The negative rate was due to the exfoliation behavior and was nonlinear to the photodegradation time. Keywords: Microplastics / Polypropylene / Photodegradation / Surface Exfoliation / Water |
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| 配列が制御された新規生分解性コポリマーの設計と合成 Design and Synthesis of Novel Biodegradable Copolymers with Controlled Sequence |
中山 祐正 Yuushou NAKAYAMA |
| ＜要旨＞ Poly(glycolic acid) (PGA), poly(L-lactide) (PLA) and polyamide 4 (PA4) have been known for their biodegradability. We developed a series of novel sequential copolyesters and copoly(ester amide)s containing the repeating units of common polyesters such as poly(ethylene terephthalate) (PET) as well as those of PGA, PLA or PA4 as new biodegradable polymers. The 2 : 1 condensation products of hydroxy acids (L-lactic acid or glycolic acid) and ethylene glycol were polymerized with terephthaloyl chloride to produce novel sequential polyesters, poly(GEGT) and poly(LELT), respectively. Poly(GEGT) showed relatively high melting temperature (Tm) while poly(LELT) was amorphous. Poly(GEGT) exhibited high biodegradability in seawater. We also synthesized a series of new sequential copoly(ester amide)s containing γ-aminobutyric acid (GABA) units. The copoly(ester amide)s showed higher thermal stability and lower Tm than those of PA4, indicating their improved processability. The copoly(ester amide)s also exhibited biodegradabiity in seawater depending on their structure. Keywords: Sequential Copolymer / Copolyesters / Copoly(ester amide)s / Glyclic Acid / Lactic Acid / γ-Aminobutyric Acid / Diol / Dicarboxylic Acid |
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| 天然型高分子PHBHの材料化 The Naturally Occuring Polymer PHBH and its Realisation |
佐藤 俊輔 Shunsuke SATO |
| ＜要旨＞ We have been developing “KANEKA Biodegrable Poymer PHBH®” as an environmentally compatible material with technical integration of fermentation, downstream process and polymer processing technology. PHBH consists of 3-hydroxybutyrate and 3-hydroxyhexanoate(3HHx) and is a naturally occuring biopolymer synthesized by a bacterium as an energy and carbon storage material. Thus, PHBH has exellent biodegradability in various environments including the ocean. So, we believe that PHBH could be one of the solutions for the current marine pollution problem. To realise PHBH, it is highly important to regulate the fractions of 3HHx since the material and mechanical properties of the PHBH depend on the fractions of 3HHx. Therefore, we examined the precise control of the 3HHx fractions by fine-tuning the expressions of phaJ, the genes encoding enoyl-CoA hydratases, which are responsible in the intracellular supply of 3HHx and by regulating the reactivity of the PHBH polymerizing enzyme (PhaC) against 3HHx. To make plastics a truly environmentally friendly material, it will be important for manufactures and users to be smarter. Keywords: PHBH / Naturally Occurring Polymer / Biodegradable / Marine Pollution |
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| グローイングポリマー Polymer Science and I: A Personal Account |
| 自身のプレゼンスは何か What's Your Strength ? |
兼橋 真二 Shinji KANEHASHI |
| ＜要旨＞ This personal essay is written by Dr. Shinji Kanehashi. I talk about my career and the key points that influenced my thoughts as an independent researcher. |
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| 高分子科学最近の進歩 Front-Line Polymer Science |
| 生分解性プラスチックの高性能化に向けた最近の進歩 Recent Development in the High-Performance of Biodegradable Biomass Plastics |
岩田 忠久 Tadahisa IWATA |
| ＜要旨＞ To establish a sustainable material production system and preserve the beautiful global environment forever, it is desirable to develop “biomass plastics” that are made from renewable biomass instead of petroleum, and “biodegradable plastics” that are completely degraded into carbon dioxide and water by enzymes secreted by microorganisms in the environment. This front-line describes recent development in the high-performance biodegradable biomass plastics. In particular, some important and interesting researches will be presented, focusing on biodegradable initiation functions and marine biodegradability. Keywords: Biodegradable Biomass Plastics / Biodegradable Plastics / Marine Biodegradation / Biodegradable Initiation Function / BOD-Biodegradation / Enzymatic Degradation / Deepsea Biodegradation |
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| ポリマーセレクト Polymer Select |
| 高分子固体階層構造の特質解明のために Elucidation of the Characteristics of Hierarchical Structures of the Solid State of Polymers |
田代 孝二 Kohji TASHIRO |
| ＜要旨＞ In order to elucidate the detailed characteristics of the hierarchical structure of crystalline polymer solids, a systematic research has been conducted by studying their formation process and their relation to the physical properties of polymers. In these researches, such a wide variety of methods have been utilized as wide-angle/small-angle X-ray scattering, neutron scattering, electron diffraction, infrared and Raman spectroscopy, and computer simulations containing lattice dynamics, molecular dynamics and density functional theory. Some concrete results are described in detail and the future of structural science of polymer solids has been discussed. Keywords: Polymer Solid / Hierarchical Structure / Structural Evolution Process / X-ray Scattering / Neutron Scattering / Electron Diffraction / Vibrational Spectroscopy / Computer Simulation |
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