群馬大学/大学院理工学府/環境創生部門/河原研究室

GUNMA UNIVERSITY, Environmental Engineering Science
KAWAHARA Lab

376-8515 桐生市天神町1-5-1
TEL/FAX 0277-30-1491

1-5-1 Tenjin-cho, Kiryu, Gunma 376-8515, JAPAN
Email/kawahara at gunma-u.ac.jp
メールの時は、アドレスのatを＠にしてください


(作成日2006.11.4, 更新日2024.10.10)

＜重要なお知らせ!!＞
河原研究室は、河原が2025年3月末で群馬大学を退官予定のため、退官と同時に閉鎖になります。 長きに渡りご興味を頂戴しました関係者の方々、 ご支援いただきました皆々様に厚く御礼申し上げます。 なお、2025年4月からは個人の研究所としまして、 「河原技術研究所」を横浜市緑区（最寄り駅：長津田）に開所予定です。 是非、お気軽にご相談ください。河原への連絡には、これまで通りのメールアドレスをご利用いただける予定です。

研究室の紹介ビデオです「カイコの先生に会いに行こう！」 Please click here!

病気（ビタミンA欠乏症、肺炎、肝炎）が毛の構造を変化させることを調べました! Please click here!

生物材料を通じて生命の不思議を知ろう! Please click here!

カイコの糸づくり（紡糸）につての総合論文 Please click here!

動･植物の未利用バイオマスからのエコ素材の製造技術開発を行っています。 人類は生物由来材料を巧みに生活に利用して発展してきました。 そこで、合成化学物質を使用しなくても 「水と熱と生物の産生物だけで、使える材料は開発できないか！」、 と思い取り組んでいます。 今は杉の間伐材と廃棄羽毛から擬木（ぎぼく）を作る研究をしています。 将来的には、弦楽器用のカエデなどの高級広葉樹の擬木を作りたいと考えています。 水と生物材料のみから作られるため、とても人に優しい材料になります。 また、実験する学生さんにとっても、とても安全で、 化学物質の人体への影響を心配する必要はありません。 間違って目に入れても、飲み込んでも、人類の長い歴史の中で共存していたものだけを出発原料としているため、 とても安全です。さらに、最近は、カイコの代謝と繭の関係を調べています。 カイコは群馬とゆかりの深い生物ですが、ストレスに強いたくましい蚕の作る繭糸は、とても繊細で奥深いです。 一緒に体験してみませんか？人にやさしい素材開発を体験できる研究室です。




これまでの研究開発プロジェクト

Coffee break

河原　豊の略歴

1985年3月　東京工業大学大学院理工学研究科有機材料工学専攻修士課程修了
1985年4月　日本鋼管株式会社中央研究所
1988年6月　東京都立繊維工業試験場
1998年4月　京都工芸繊維大学大学院工芸科学研究科　助教授
2006年6月　群馬大学工学部生物化学工学科　教授
2007年4月　群馬大学大学院工学研究科応用化学・生物化学専攻　教授
2013年4月　群馬大学理工学研究院環境創生部門　教授(現在に至る)

学位：1996年3月　東京工業大学、有機材料工学専攻、博士（工学）

研究スタッフ

学生の自主性を重んじる研究室です（B4：4名, 2024年度）



研究の内容

高分子工学を基礎とした高分子の高次構造制御と機器分析（X線回折、熱分析、粘弾性測定、等）による物性評価を通じて、環境素材開発を行う



エレクトロスピニング法によるナノファイバーの開発

エレクトロスピニング法により作製したポリジオキサノンナノファイバーの構造研究

ナノファイバーの暗視野像観察から，ナノファイバー中に積層ラメラ構造の存在を確認することができた．
























Fig.1 Dark-field image of the heat-treated electrospun PPDX nanofibers by using the 210 and 020 reflections.

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    ナノファイバーの製造に関する研究論文

    1.中山　篤，河原　豊, 早川喜教，高橋良輔，吉岡太陽，辻　正樹，繊維学会誌, 63, 230-234(2007), エレクトロスピニング法により作製したポリジオキサノンナノファイバーのモルフォロジー研究.
    2.Yutaka Kawahara, Atsushi Nakayama, Noriaki Matsumura, Taiyo Yoshioka and Masaki Tsuji, Structure for Electro-spun Silk Fibroin Nanofibers, Journal of Applied Polymer Science, Volume107, 3681-3684(2008).
    3.Yutaka Kawahara, Satoshi Naruko, Atsushi Nakayama, Ming-Chien Wu, Eamor M. Woo, Masaki Tsuji, Stacked-lamellar Structure of Electrospun Poly(heptamethylene terephthalate) Nanofibers, Journal of Materials Science, 44, 2137-2142(2009).
    4.西川午郎、山本真揮、Amalina M. Afifi、河原　豊、山根秀樹、溶融エレクトロスピニング法により製造したポリ乳酸繊維の構造、繊維学会誌，66(5), 124-129 (2010).
    5.Taiyo Yoshioka, Yutaka Kawahara, Masaki Tsuji, Andreas K. Schaper, Structural Modification of PVA Nanofibers by Water Vapor Annealing, Sen’I Gakkaishi, 67(6), 138-140 (2011).
    6.Yoshioka, Taiyo; Kawahara, Yutaka; Schaper, Andreas, Cyclic or permanent ? Structure control of the contraction behavior of regenerated Bombyx mori silk nanofibers, Macromolecules, 44, 7713-7718(2011).
    7.Andreas K. Schaper, Taiyo Yoshioka, Yutaka Kawahara, Fascinating Silk- Electrospinning, Contraction and Diffraction Experiments, G.I.T. Imaging & Microscopy, Volume 14, Issue 2, 25-27 (2012).
    8.Yutaka Kawahara, (1→3)- β-D-Glucan nanofibers from paramylon via electrospinning, Carbohydrate Polymers, DOI: 10.1016/j.carbpol.2014.05.066, vol. 112, 73-76 (2014).
    9.Yutaka Kawahara, Electrospinning of Direct Carbonizable Phenolic Resin-based Nanofibers, Journal of Textile Science & Engineering, 6(3), 257 (2016).

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    液状絹からの新素材の創造
    「シルクフィルム・スポンジの開発」

    研究内容

    絹は、人にやさしく、衣料にとどまらず「快適で健康な生活」を求める社会ニーズに対応した素材である。 そこで、われわれは、実用的な絹フィルムの生産技術開発を行った。 　図１に新しい絹フィブロインフィルムの製造技術の概念図を示す。 最近は、カイコの絹糸腺から液状絹を分離してフィルムの製造を研究している。 図２に液状絹を用いて作製したスポンジの電子顕微鏡写真を示す。













    Fig.1 新しい絹フィブロインフィルムの製造技術の概念図


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    Fig.2 開発中の液状絹のスポンジ

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    シルクフィルムの開発技術に関する研究論文

    1.Yutaka Kawahara, Keiko Furukawa, Takeshi Yamamoto, Self-Expansion Behavior of Silk Fibroin Film, Macromol. Mater. Eng., 291, 458-462 (2006).
    2.河原　豊, 古川敬子, 山本岳志, 益田美和, 古薗　勉, 柔軟な絹フィブロインフィルムの開発, 日本シルク学会誌, 15, 3-6 (2006).
    3.河原　豊, 非結晶性フィブロインフィルム及びその製造方法，特願２００８−１３４８９４.
    4.Yutaka Kawahara, Akira Ito, Separation of Ethanol-Water Mixtures by the Membranes Prepared from Liquid Silk, 繊維学会誌，70(2), 23-27 (2014)．
    5.河原　豊，フィブロインのセリシン共存下における結晶化挙動, 日本シルク学会誌，22, 39-45（2014）.
    6.Alina Kudasheva, Yuichiro Hirota, Yutaka Kawahara, Akira Ito, Application of Biopolymers in Air Dehumidification Membranes. Journal of Chemical Engineering of Japan, 48(12), 960-965 (2015).
    7.河原　豊，藤井秀彰，宝田　亘，鞠谷雄士，桑原伸夫，樹状構造を発現した液状絹エアロゲルの構造，日本シルク学会誌，24, 5-10 (2016).

    ミドリムシ産生多糖パラミロンからのフィルムの開発に関する研究

    研究内容

    湖沼に生息するミドリムシは世界に１００種類以上いて、貯蔵糖として パラミロンと呼ばれる(1→3)-β-D-グルカンを生産するが、パラミロンの構造が３重螺旋構造で 安定なため、利用が遅れていた。研究室ではミドリムシからのパラミロンの分離技術と、 再生フィルム・繊維の生産技術の開発を行った。 キャストフィルムは透明感があり優れた力学特性を示した。ＰＶＡとのブレンドによってフィルム強度は低下したが、 市販の生分解フィルムと同程度の物性を示した。 繊維の開発はこれからだが、基本的な紡糸技術の開発は達成することができた。





    Fig.1 Tensile strength of regenerated films prepared using paramylon from Euglena Gracilis.







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    Fig.2 Aspect of regenerated film.














    Fig.3 Aspect of regenerated blend fibers.




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    パラミロンフィルム＆繊維に関する研究論文

    1.Yutaka Kawahara, Akihiro Koganemaru, Development of Novel Film Using Paramylon Prepared from Euglena Gracilis, Journal of Applied Polymer Science, Vol.102, pp.3495-3497(2006).
    2. Yutaka Kawahara, (1→3)- β-D-Glucan nanofibers from paramylon via electrospinning, Carbohydrate Polymers, Vol. 112, pp. 73-76 (2014).
    3. 河原　豊，パラミロン, “バイオベースマテリアルの新展開/New Development of Bio-based Materials”＜普及版＞（木村良晴，小原仁実，監修）， シーエムシー出版，2012年10月10日発行.








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    食品廃棄物等有機系産業廃棄物からの活性炭の製造に関する研究

    研究内容

    活性炭は水質浄化、空気清浄、ガスの分離などに利用されており、 環境保全関係やファインケミカルなどの方面にも多くの応用例があり、 今後もその需要は増加傾向にある。現在、炭素材料の多くは、石油・石炭工業からの ピッチ、コークス等から生産されている。しかし、環境問題、化石資源の渇枯が懸念されており、 将来、国内の活性炭業界は原料不足に直面する可能性がある。 新しい炭素材料の原料として食品廃棄物や有機系産業廃棄物の利用を含め、 可能性を調査する必要がある。 これまで、食品廃棄物のうち、小麦殻のフスマと、 ビール粕について活性炭の試作に成功している。食品廃棄物ではタンパク質の影響を考慮するが、 竹についてはミネラルの影響を考慮した。

    賦活ガス化反応におけるカリウム含有量の影響

    カリウム含有量が増加するとガス化反応が速くなる。
    しかし、生体構造に関係なくランダムにガス化が進み細孔分布が鈍化する。

























    Fig.1 Influence of Potassium on TG curves of carbonized bamboos.
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    トリプトファンの熱重縮合物に見られるネマチック組織

    アセナフチレンピッチに匹敵する黒鉛化度を示した。

    Fig.2 Polarizing transmitted light micrographs of thin film of L-tryptophan heat-treated at 500 oC for 2h representing anisotropic flow-type texture of mesophase. Scale bars correspond to 50 μm.



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    食品廃棄物等からの活性炭製造に関する研究論文

    1.河原　豊, 西川午郎, 金井宏彰, 瀧川久幸, 繊維学会誌, 57, 298-300(2001), コカナダモの炭化挙動と炭化物の利用.
    2.西川午郎, 河原　豊, 繊維学会誌, 59(5), 163-167(2003), ふすまの炭素化挙動と炭素化物の利用.
    3.西川午郎, 河原　豊, 塩谷正俊, 繊維学会誌, 60(4), 105-111(2004), 絹の炭素化挙動．
    4.脇坂博之, 三宅　肇, 河原　豊, ビールかすからの活性炭の製造および含有タンパク質の賦活工程への影響, 炭素, No.218, 192-196 (2005).
    5.河原　豊, 泉本匡彬, 西川午郎, 脇坂博之, 岩下哲雄, 山本和宜, 石橋　昇, 葦の炭素化挙動と活性炭の製造, 繊維学会誌, Vol.62, No.10, 242-244(2006).
    6.脇坂博之, 三宅　肇, 河原　豊, 竹からの活性炭の製造および含有カリウムによる賦活工程への影響, 炭素, No.224, 272-275 (2006).
    7.Goro Nishikawa, Masatoshi Shioya, Norio Iwashita and Yutaka Kawahara, Carbonization behavior of L-tryptophan and gluten, Journal of Materials Science, 42(6), 2076-2080(2007).
    8.河原　豊, 山本和宜, 石橋　昇, 脇坂博之, 葦由来の活性炭のカビ臭吸着性能, 繊維学会誌, 64(3), 85-87(2008).
    9.Yutaka Kawahara, Kazuyoshi Yamamoto, Hiroyuki Wakisaka, Kaori Izutsu, Masatoshi Shioya, Toshiaki Sakai, Yutaka Takahara, Noboru Ishibashi, Carbonaceous adsorbents produced from coffee lees, Journal of Materials Science, Volume 44, 1137-39(2009).
    10.Kazuyoshi Yamamoto, Yutaka Kawahara, Masatoshi Shioya, Noboru Ishibashi, Utilization of triacetylcellulose waste for the production of carbonaceous adsorbents, Journal of Polymers and the Environment, Volume 20, Issue 2, 626-630.(2012).
    11.Noboru Ishibashi, Kazuyoshi Yamamoto,Hiroyuki Wakisaka, Yutaka Kawahara, Influence of the hydrothermal pre-treatments on the adsorption characteristics of activated carbons from woods, Journal of Polymers and the Environment, Vol. 22, Issue 2, 267-271(2014).

    12.Yutaka Kawahara, Noboru Ishibashi, Kazuyoshi Yamamoto, Hiroyuki Wakizaka, Norio Iwashita, Seiji Kenjo, and Goro Nishikawa, Activated carbon production by co-carbonization of feathers using water-soluble phenolic resin under controlled graphitization, Sustainable Materials and Technologies, Vol. 4, 18?23 (2015).
    13.Hiroyuki Wakizaka, Hajime Miyake, Yutaka Kawahara, Utilization of beer lees waste for the production of activated carbons: The influence of protein fractions on the activation reaction and surface properties, Sustainable Materials and Technologies, 8, 1-4 (2016).
    14.Yutaka Kawahara, Hiroyuki Wakizaka, Kazuyoshi Yamamoto, and Noboru Ishibashi, Preparation of bamboo-based carbonaceous adsorbents for the removal of musty/earthy off-odors and VOCs, International Journal of Water and Wastewater Treatment, Volume 2 issue 4: doi. http://dx.doi.org/10.16966/2381-5299.124.
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    羽毛ケラチン加水分解物の含浸による出土（劣化）木材の細胞壁補強（バルキング）効果

    研究内容

    羽毛ケラチン加水分解物を用いた出土木材の処理では微生物の生命活動によって 劣化した細胞壁にケラチンが直接、浸入してリグニン質と複合化するため 細胞壁が補強され、出土木材を室内に放置しても水分移動による 変形、収縮が抑えられ、出土時の寸法が保存される。

    寸法安定効果




    Fig.1 Appearance of archaeological waterlogged wood specimens dried: a, untreated, and the specimens treated with duck feather solutions of b, 10%, c, 20%, d, 30% and e, 40%.
    ケラチンの出土木材の寸法安定効果
    未処理材（左端）に比べて出土したときの寸法が処理材（右端）では保存されている



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    補強効果




    ←Fig.2 Compressive stress-strain curves of arhcaeological waterlogged wood specimens.
    ケラチンの劣化木質細胞壁補強効果

    →Fig.3 Scanning electron micrograph of the cross-section for archaeological waterlogged wood specimens treated with duck feather hydrolysate. Scale bar = 10μm.


    劣化細胞壁がケラチンのバルキング作用によって直接補強されるため、 細胞内部が完全にケラチンで充填されていなくても大きな補強効果を生じる。

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    出土木材の保存処理に関する研究論文

    1.遠藤利恵, 河原　豊, 羽毛加水分解物による出土木材の抗収縮・補強作用, 繊維学会誌, 60, 372-376(2004).
    2.遠藤利恵, 河原　豊, 亀井加恵子, 羽毛加水分解物を用いた出土木材の保存処理, 繊維学会誌, 60(4), 125-129(2004).
    3.Yutaka Kawahara and Rie Endo, Chemical Finishing of Bast Fibers and Woods Using Hydrolyzed Keratin from Waste Wool or Down, Textile Research Journal, 74(2), 93-96 (2004).
    4.Rie Endo, Kaeko Kamei, Ikuho Iida and Yutaka Kawahara, Dimensional stability of waterlogged wood treated with hydrolyzed feather keratin, Journal of Archaeological Science, Volume 35, 240-1246(2008).

    ケラチンの自己組織化に関する研究論文

    1.Yutaka Kawahara, Makoto Ikegami, Atsushi Nakayama, Yuichi Tsuda, Seiji Kenjo Masaki Tsuji, Morphological Studies on Assembling Behavior of Oligopeptides Obtained by Dissolution of Feather Keratin with Alkali, 繊維学会誌，65(11), 319-323(2009).
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    植物繊維の高性能化に関する研究

    分離技術

    植物繊維の高機能化をもう一つの 大きな研究課題と考え取り組んでいる。 図は、二酸化炭素の固定に優れていると されているケナフの茎の靭皮部 から繊維を分離するとき、アルカリ水溶液 の濃度を変化させたときの様子 である。単純なことであるが、 繊維表面の状態が大きく変化する。最近、 自動車の部材として植物繊維で強化した プラスチック部品が内装材を中心 に利用されているが、複合材料の プラスチックと繊維との界面を考えるとき、 このような基本的な繊維抽出技術が 大きく影響する。










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    審美性の追求

    植物繊維の光沢度は審美性に影響する。審美性を向上させるために、 アルカリを使わない酵素を用いた精練技術の開発をしている。 伝統的な雑菌による方法に比べて、酵素精練の方が短時間で光沢度の 向上した繊維が得られる。下にクズ繊維の結果を示す。伝統手法の場合、 一週間を要するが、酵素精練では８時間で十分である。

    Relative luster of kudzu fibers retted with enzymes. Incident beam angle was set at 15°from horizontal and regular reflection was measured along to the fiber axis. ■viscozyme L, ■ ultrazyme 100G, ■ pectinase G, ■ pectinase PL, ■ hemicellulase 90, ■water-retting (preboild) and ■water-retting (normal).





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    植物繊維の高性能化に関する研究論文

    1.河原　豊, 遠藤利恵, 川下剛生, 靭皮繊維の紫外線劣化における鉄およびケラチン処理の効果, 繊維学会誌, 58(8), 314-316(2002).
    2.河原　豊, 川田雄補, 遠藤利恵, 南　秀明, 西内滋典, 水熱処理によるジュート繊維の中間ラメラの崩壊, 繊維学会誌, 61, 142-145(2005).
    3.河原　豊, 崎山貴之, 遠藤利恵, メタクリルアミド処理したジュート繊維の力学特性, 繊維学会誌, 61, 138-141(2005).
    4.河原　豊, 田処圭一, 遠藤利恵, 塩谷正俊, 杉村順夫, 古澤壽治,Chemically Retted Kenaf Fibers, 繊維学会誌, 61, 115-117(2005).
    5.Yutaka Kawahara, Tomoyuki Tsuda, Hideaki Minami, Shigenori Nishiuchi, and Rie Endo, Enzymatic Retting of Kudzu Fibers, Journal of Applied Polymer Science, Vol.106, Issue 4, 2759-2762 (2007).
    6.南　秀明, 西内滋典, 門野純一郎, 杉村順夫, 河原　豊, ケナフ靭皮繊維の中間ラメラへの水熱処理の影響, 繊維学会誌，65(12), 338-343(2009).
    7.Akihiro Nishimura, Hisato Katayama, Yutaka Kawahara, Yukio Sugimura, Characterization of kenaf phloem fibers in relation to stem growth, Industrial Crops and Products, 37(1), 547-552 (2012).
    8.Yutaka Kawahara, Yo Saito, Kiyoshi Yamamoto, Yoshimitsu Ikeda, and Yukihiro Nishikawa, Study on the Application of Kenaf Core as a Composite Reinforcement: Injection Molding of Kenaf Core/ Poly(L-lactide) Compounds. Journal of Natural Fibers, Published online: 06 Feb 2017. http://dx.doi.org/10.1080/15440478.2016.1266293

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    s-CO2環境場のポリエステル繊維の構造変化とシシケバブ構造の存在

    高速紡糸したPET繊維の粘弾性測定から示唆されるシシケバブ構造の存在

    s-CO2環境場で生成する不完全な微結晶は損失弾性率を低下させピーク温度を高温側にシフトさせ分子鎖 の運動性を低下させるが、このようなs-CO2環境場での構造変化は分子鎖の緩和現象を伴うため、 通常、貯蔵弾性率が低下する。しかし、貯蔵弾性率は増加しており、これは、 積層ラメラ晶間を連結する安定なシシ骨格の存在を示唆する。

    Fig.1 Temperature dependence of dynamic storage modulus E’and loss modulus E”for HSS (6km/min) fiber: ○, control; ●, s-CO2 treared.(Kawahara, Y., Kamo, M., Yamamoto, K., Ogawa, S., Terada, D., Kikutani, T., Tsuji, M., Oligomer Deposition on the Surface of PET Fiber in Supercritical Carbon Dioxide Fluid, Macromol. Mater. Eng., 291, 11-15 (2006)).
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    PBT薄膜のTEM観察で発見されたシシケバブ構造



    モデル図に示すような積層ラメラ晶を貫く細いシシ骨格の存在が確認された

    Fig.2 Each of the recognized stacked-lamellar structures in uniaxially oriented thin films of poly(butylene terephthalate) is assigned to a shish-kebab structure or a part of it (Yoshioka T, Tsuji M, Kawahara Y, Kohjiya S, Manabe N, Yokota Y. Polymer 2005; 46:4987).



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    ポリエステル繊維・フィルムの構造に関する研究論文

    1.Yutaka Kawahara and Takeshi Kikutani, Journal of Macromolecular Science Physics, B39, 561-567(2000). Diffusion of Organometallic Compounds into High-speed Spun Poly(ethylene terephthalate) Fiber in Supercritical Carbon Dioxide Fluid.
    2.Yutaka Kawahara, Taiyo Yoshioka, Masaki Tsuji, Masayoshi Ohara, Shinzo Kohjiya, and Takeshi Kikutani, Journal of Macromolecular Science Physics, B39, 701-710(2000). Transmission Electron Microscopic Investigation of the Morphology of High-Speed Spun Poly(Ethylene Terephthalate) Fibers.
    3.Yutaka Kawahara, Takeshi Kikutani, and Masaki Tsuji, AATCC Review, Influence of Interfibrillar Voids and Surface Morphology on Dyeing High-Speed Spun PET Fibers, 1(2), 34-38(2001).
    4.Yutaka Kawahara, Taiyo Yoshioka, Kazuaki Sugiura, Satoshi Ogawa, and Takeshi Kikutani, Journal of Macromolecular Science Physics, B40(2), 189-197(2001). Dyeing Behavior of High-Speed Spun Poly(Ethylene Terephthalate) Fibers in Supercritical Carbon Dioxide.
    5.河原　豊, 杉浦和明, 小川　賢, 鞠谷雄士, 繊維学会誌, 57, 220-223(2001), 超臨界二酸化炭素流体処理したポリエチレンテレフタレート繊維の構造.
    6.Yutaka Kawahara, Takeshi Kikutani, Kazuaki Sugiura and Satoshi Ogawa, Coloration Technology, 117(5), 266-269(2001). Dyeing behaviour of poly(ethylene terephthalate) fibres in supercritical carbon dioxide.
    7.Yutaka Kawahara, Taiyo Yoshioka, Masaki Tsuji, Takeshi Kikutani, Kazuaki Sugiura, and Satoshi Ogawa, Morphology of High-speed Spun Poly(ethylene-2,6-naphthalene dicarboxylate) Fiber and its Structural Changes by the Treatment in Supercritical Carbon Dioxide Fluid, J. Macromol.Sci.-Phys., B41(1), 177-184(2002).
    8.Yutaka Kawahara, Masatoshi Shioya, and Takeshi Kikutani, Swelling Behavior of High-speed Spun Poly(ethylene terephthalate) Fibres, J. Macromol.Sci.-Phys., B41(2), 397-406(2002).
    9.Taiyo Yoshioka, Masaki Tsuji, Yutaka Kawahara, Shinzo Kohjiya, and Takeshi Kikutani, Permanganic Etching of Poly(ethylene terephthalate) Fibers, Sen'i Gakkaishi, 58(7), 268-272(2002).
    10.寺田堂彦, 河原　豊, 鞠谷雄士, 繊維学会誌, 58(9), 342-345(2002), 顕微レーザーラマン分光分析法 によるPET繊維の構造解析.
    11.Taiyo Yoshioka, Masaki Tsuji, Yutaka Kawahara, Shinzo Kohjiya, Takeshi Kikutani, and Hiraku Ito, A Study on the Fibrillar Structure Formed in Poly(ethylene naphthalate) Fibers, Ann. Rep. Res. Inst. Chem. Fib. , Jpn., 59, 1-9(2002).
    12.寺田堂彦, 河原　豊, 繊維学会誌, 59(10), 385-391(2003), 超臨界二酸化炭素流体処理によるポリエステル 新合繊の構造変化.
    13.Taiyo Yoshioka, Masaki Tsuji, Yutaka Kawahara, and Shinzo Kohjiya, Morphological study by TEM on uniaxially oriented thin films of PET, PEN and their blends, Polymer, 44, 7997-8003(2003).
    14.寺田堂彦, 河原　豊, 鞠谷雄士, 繊維学会誌, 60(12), 357-364(2004), 超臨界二酸化炭素流体処理によるポリエステル繊維の構造変化.
    15.Yukiko Furuhashi, Atsushi Nakayama, Teruo Monno, Yutaka Kawahara, Hideki Yamane, Yoshiharu Kimura, Tadahisa Iwata, X-Ray and Electron Diffraction Study of Poly(p-dioxanone), Macromol.Rapid. Commun. , 25, 1943-1947(2004).
    16.Taiyo Yoshioka, Masaki Tsuji, Yutaka Kawahara, and Shinzo Kohjiya, Morphological Study on Uniaxially Oriented Thin Films of Poly(butylenes terephthalate)[PBT], Ann. Rep. Res. Inst. Chem. Fib., Jpn., 61, 33-39(2004).
    17.Taiyo Yoshioka, Masaki Tsuji, Yutaka Kawahara, Takeshi Kikutani and Shinzo Kohjiya, Internal fine structures in the high-speed-spun fibers of poly(ethylene 2,6-naphthalene dicarboxylate), Polymer, 46, No.6, 1886-1892(2005).
    18.Taiyo Yoshioka, Masaki Tsuji, Yutaka Kawahara, Takeshi Kikutani and Shinzo Kohjiya, Internal fine structures in the high-speed-spun fibers of poly(ethylene 2,6-naphthalene dicarboxylate), Polymer, Volume 46, Issue 14, 27 June 2005, Pages 5429-5432.
    19.Taiyo Yoshioka, Masaki Tsuji, Yutaka Kawahara, Shinzo Kohjiya, Norio Manabe and Yoshimitsu Yokota, Morphological study by TEM on uniaxially oriented thin films of PBT, Polymer, 46, No. 14, 27 June 2005, pp. 4987-4990.
    20.Yutaka Kawahara, Masaki Kamo, Kiyoshi Yamamoto, Satoshi Ogawa, Douhiko Terada, Takeshi Kikutani, Masaki Tsuji, Oligomer Deposition on the Surface of PET Fiber in Supercritical Carbon Dioxide Fluid, Macromol. Mater. Eng., 291, 11-15 (2006).
    21.Yutaka Kawahara, Tomohiro Kurooka, Dohiko Terada, Changes in Tensile Properties for the PET Films by the Treatment in Supercritical Carbon Dioxide Fluid, Journal of Materials Science, Volume 43, 6866-6871(2008).
    22.Yutaka Kawahara, Satoshi Naruko, Atsushi Nakayama, Ming-Chien Wu, Eamor M. Woo, Masaki Tsuji, Morphological studies on single crystals and nanofibers of poly(heptamethylene terephthalate), Journal of Materials Science, Volume 44, 4705-4709(2009).
    23.Taiyo Yoshioka, Yutaka Kawahara, Takeshi Kikutani, Masaki Tsuji, Stacked-Lamellar Structure in High-Speed Spun PET Fibers as Revealed by TEM, J. Macromol. Sci., Part B, Phys., 49, 155-162 (2010).
    24.Yutaka Kawahara, Atsushi Nakayama, Masatoshi Shioya, Masaki Tsuji, Hideki Yamane, Tadahisa Iwata, Supramolecular Morphology of Two-Step, Melt-Spun Poly(dioxanone) Fibers, Journal of Materials Science, Volume 47, Issue 4 (2012), Page 1887-1892.
    25.Yutaka Kawahara, Taiyo Yoshioka, Wataru Takarada, Takeshi Kikutani, and Masaki Tsuji, Alkaline Hydrolysis Kinetics of Poly(ethylene terephthalate) Fibers, Journal of Fiber Science and Technology, 72(1), 9-16 (2016).
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    "Etached surface of HSS PET fibers"

    TEM observation for high speed spun PET fibers revealed that the fiber takes stacking lamella structure and the stacking direction is declined against fiber axis by ca. 35 degree and the long period is in the range of 10-30 nm. These results almost coincide with the model structure proposed by Shimizu et al.

    Fig. (a) Bright-field image for a replica of an etched HSS-PET fiber (spun at 6km/min). Image (b) was enlarged with higher contrast from the white rectangular portion in image (a).

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    5代目ハムの"くろ"です！

    人生は短し、学なり難し、"くろ"の代謝速度で脳が動けば・・・・・




















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    小山先生（山形大学長）からレオロジーの講義を受けました(ポリマー/フィラー界面と見かけ粘性の関係)。
    先生の笑顔が深く心に残りました(2017, 9月)





















































































    楽しかったこと, OBが研究室を持ちました！父の日のうなぎの蒲焼！(2013, 6月)































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    卒研風景(2012-13)、彼らの指先に注目！


    初めてのエスカルゴの味は？






























    研究室風景(2011, 11月)




































    OB会-京都工繊大の卒業生(2011, 3月, 京都)









































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    Hessen州からBayern州を訪問(2009, 9月)
















































    Philipps 大学マールブルグ（ドイツ）のSchaper先生！筑波山の山頂に立つ！！(2009, 3月)



    Schaper先生in 横浜(2013, 4月)




































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    プサン（韓国）の大先輩とお寺を訪問(2006, 11月)























    メルボルン（オーストラリア）の友人Cao先生の中庭(2005, 11月)



    お久しぶりCao先生in国立博物館(上野, 2013, 5月)







































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    Welcome to KAWAHARA Lab!

    GUNMA UNIVERSITY, Environmental Engineering Science
    Prof. Dr. Yutaka KAWAHARA, supervisor


    1-5-1 Tenjin-cho, Kiryu, Gunma 376-8515, JAPAN
    TEL/FAX +81-277-30-1491
    Email/kawahara at gunma-u.ac.jp
    When you contact, please replace "at" to "＠".



    (Last Update: 2024.10.10)

    ＜IMPORTANT NOTICE!!＞
    Kawahara Lab. will soon be closed by the end of March, 2025 due to the mandatory age-limit retirement. I would like to give thanks for your interests and good supports. On April 1st, 2025, I will open my private laboratory standing near Nagatsuta station in Midori-ku Yokohama city. Please visit my "Kawahara Technology Research Laboratory.”My present E-mail address is going to be still available for a while after my retirement.

    Video Report















    Experiments on the Forcibly Spinning of Bombyx mori silkworm!


    Recent Reports

    “Possible relationships between the physical conditions of cattle and the occurrence of structural modifications of their coat hair”

    “Comprehensive Study on the Formation of Higher-Order Structure of Bombyx mori Silkworm Fibers: Influence of Sericin Fractions, Modulation of Spinning Process, and Metal Ion Interactions”

    “Recrystallization Behavior and Mechanical, and Carbonizing Properties of Feather Keratin Resin Sheets Produced by Hot-Compression Molding”


    Past Projests

    Coffee break

    Introduction to Biomass Science

    Biomass is a keyword for the sustainability society. Silk has been used as a textile material in our daily life and silk garments sometimes represent culture and status for human beings. Nowadays, additional functional properties have been found out for silk from the viewpoints of food industry, cosmetic material, medical use etc. It is nothing but silk is a reproducible material. When we consider the construction of bio-production system, silk is a very promising material. Also, it is essential for the sustainability society to expand industrial use of vegetable fibers. However, physical and chemical natures of vegetable fiber have not been fully established so far. Frontier works are needed for opening this potential research field, which definitely contributes to global sustainability.



    CV of Prof. Kawahara

    1.Education: Tokyo Institute of Technology, 1983 BA., 1985 MS., 1996, Dr. Eng.
    2.Previous Employment:
    1985-Researcher, NKK CORPORATION
    1988-Researcher, Tokyo Metropolitan Textile Research Institute
    1998-Associate Professor, Kyoto Institute of Technology
    2006-Present affiliation
    3.Awards:
    (1) Paper prize of the Japan Society of Polymer Processing, 1991.
    (2) Paper prize of the Society of Fiber Science and Technology Japan, 1994.




    Electrospinning of Biodegradable Nanofibers

    Structural Study on Electrospun Nanofibers of Polydioxanone

    Nanofibers of polydioxanone (PPDX) were electrospun from 3.0-wt% solution in 1,1,1,3,3,3-hexafluoro-2-propanol. Structure and morphology of the electrospun nanofibers were investigated by transmission electron microscopy (TEM). In order to align and collect nanofibers parallel to each other, we used a homemade collector with separated electrodes which was specially designed. TEM revealed that thus aligned nanofibers on the collector are partially crystallized. The SAED patterns of nanofibers, which were drawn and/or heat-treated with being deposited on the collector, showed a well-developed fiber pattern. In the dark-field image of heat-treated nanofibers, many striations which are running perpendicular to the fiber axis were observed. These striations appear to be a part of stacked-lamellar structure oriented in the direction of fiber axis. This result indicated that heat-treated PPDX nanofibers have stacked-lamellar structure.



















    Fig.1 Dark-field image of the heat-treated electrospun PPDX nanofibers by using the 210 and 020 reflections.
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    Articles Published

    1.Atsushi Nakayama, Yutaka Kawahara, Yoshitaka Hayakawa, Ryosuke Takahashi, Taiyo Yoshioka, and Masaki Tsuji, Sen'i Gakkaishi, 63, 230-234(2007), Structural study on electrospun nanofibers of polydioxanone.

    2.Yutaka Kawahara, Atsushi Nakayama, Noriaki Matsumura, Taiyo Yoshioka and Masaki Tsuji, Structure for Electro-spun Silk Fibroin Nanofibers, Journal of Applied Polymer Science, Volume107, 3681-3684(2008).
    3.Yutaka Kawahara, Satoshi Naruko, Atsushi Nakayama, Ming-Chien Wu, Eamor M. Woo, Masaki Tsuji, Stacked-lamellar Structure of Electrospun Poly(heptamethylene terephthalate) Nanofibers, Journal of Materials Science, 44, 2137-2142(2009).
    4.Taiyo Yoshioka, Yutaka Kawahara, Masaki Tsuji, Andreas K. Schaper, Structural Modification of PVA Nanofibers by Water Vapor Annealing, Sen’I Gakkaishi, 67(6), 138-140 (2011).
    5.Yoshioka, Taiyo; Kawahara, Yutaka; Schaper, Andreas, Cyclic or permanent ? Structure control of the contraction behavior of regenerated Bombyx mori silk nanofibers, Macromolecules, 44, 7713-7718(2011).
    6.Andreas K. Schaper, Taiyo Yoshioka, Yutaka Kawahara, Fascinating Silk-- Electrospinning, Contraction and Diffraction Experiments, G.I.T. Imaging & Microscopy, Volume 14, Issue 2, 25-27 (2012).

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    Ductile Soft Silk Fibroin Films

    Abstract

    Silk fibroin cast film was prepared using a ternary solvent system of CaCl2/CH3CH2OH/H2O (1/2/8 in mole ratio). A drying temperature at casting influenced crystal structure of fibroin. When a drying temperature was set lower than 9 centigrade, the cast film became amorphous. When a drying temperature was set higher than 40 centigrade, a fibroin film of silk-II structure was obtained. In order to produce a fibroin film of silk-I structure, a preferable temperature range was from 20 to 26 centigrade. The crystal transformation from random coil structure into silk-I could be made through exposure of an amorphous film to water vapor. As for the crystal transformation from silk-I into silk-II, the treatment with a glycerin solution was effective. In the course of the treatment a film showed self-thinning and self-expanding. The expansion ratio exceeded 40 % at maximum. The film produced accompanying self-expansion was ductile in nature.






    Fig.1 Newly developed technology for the production of soft ductile silk fibroin films.


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    ←Fig.2 Comparison in ductility between developed silk fibroin
    film (left side) and conventional ones.




















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    Articles Published

    1.Yutaka Kawahara, Keiko Furukawa, Takeshi Yamamoto, Self-Expansion Behavior of Silk Fibroin Film, Macromol. Mater. Eng., 291, 458-462 (2006).
    2.Yutaka Kawahara, Keiko Furukawa, Takeshi Yamamoto, Miwa Masuda, Tsutomu Furuzono, Development of Soft Silk Fibroin Film, Nippon Silk Gakkaishi, 15, 3-6(2006).
    3.Yutaka Kawahara, Akira Ito, Separation of Ethanol-Water Mixtures by the Membranes Prepared from Liquid Silk, Sen'i Gakkaishi，70(2), 23-27 (2014)．

    Development of a Biodegradable Film and Fiber Using Paramylon Prepared from Euglena Gracilis

    Abstract

    The Euglena family is classified in both vegetable and single cellular animal, a monad that can move with its tail using like a screw and synthesizes paramylon as storage polysaccharide from CO2 and solar energy. The polysaccharide consists of triple helical structure of (1→3)-β-D-glucans and has crystallinity over than 90 % though the degree of polymerization (DP) is no more than 700. Such specific properties of paramylon, that is, high crystallinity and low DP are unwelcome from a viewpoint of polymer processing. The wet process was applied to paramylon to produce stable films and fibers. Formic acid was suitable for the preparation of a solution of paramylon, and a transparent even yellow film was obtained by casting the solution on a glass plate and drying the cast film in air without using coagulation bath. The tensile strength of the regenerated film was enhanced by the treatment using hot pressurized water. The spinability of a paramylon solution was a little enhanced by blending polyvinyl alcohol (PVA) up to 70 %. The paramylon / PVA blend fibers were produced through wet spinning using coagulation bath of conc. Na2SO4 at a room temperature.





    Fig.1 Tensile strength of regenerated films prepared using paramylon from Euglena Gracilis.







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    Fig.2 Aspect of regenerated film.














    Fig.3 Aspect of regenerated blend fibers.




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    Articles Published

    1.Yutaka Kawahara, Akihiro Koganemaru, Development of Novel Film Using Paramylon Prepared from Euglena Gracilis, Journal of Applied Polymer Science, Vol.102, pp.3495-3497(2006).
    2. Yutaka Kawahara, (1→3)- β-D-Glucan nanofibers from paramylon via electrospinning, Carbohydrate Polymers, Vol. 112, pp. 73-76 (2014).








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    Production of Functional Carbons from Biomass

    Aims

    Pitches and cokes, the heavy fractions of petroleum and coal, are two major starting materials of various carbons such as carbon blacks, carbon fibers and activated carbons. Their carbonization behavior and the properties of the resulting carbons have been studied extensively. In contrast, very little attention has been paid to the carbonization behavior of natural resources.

    Pore Size Distribution of Activated Carbons from Bamboos

    The potassium fractions will accelerate the gas reaction in activation process,
    which affects the utilization of the cellular structure of vegetable.

























    Fig.1 Influence of Potassium on TG curves of carbonized bamboos.
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    The degree of graphitization of L-tryptophan is nearly equal to the carbons from acenaphthylene.

    Carbonization behavior of L-tryptophan has been investigated. The carbon derived from L-tryptophan by the heat-treatment at 3000 centigrade showed almost the same degree of graphitization as that from acenaphthylene and the average interlayer spacings of both these carbons approached to 0.3354 nm. The ratio, R, of the intensity of the Raman band at 1360 cm-1 against that at 1580 cm-1 and the half width, Dl, of the Raman band at 1580 cm-1 were measured. The R and Dl are the measures for the degree of graphitization. Those values for the carbon from L-tryptophan were nearly equal to those for the carbon from acenaphthylene.

    Fig.2 Polarizing transmitted light micrographs of thin film of L-tryptophan heat-treated at 500 oC for 2h representing anisotropic flow-type texture of mesophase. Scale bars correspond to 50 μm.



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    Articles Published

    1.Yutaka Kawahara, Goro Nishikawa, Hiroaki Kanai, Hisayuki Takigawa, Sen'i Gakkaishi, 57, 298-300(2001), Carbonization Behavior of Water Plants, Elodea Nuttallii, and Utility of Carbonized Materials.
    2.Goro Nishikawa, Yutaka Kawahara, Sen'i Gakkaishi, 59(5), 163-167(2003), Carbonization Behavior of Wheat Bran and Utility of their Carbonized Products.
    3.Goro Nishikawa, Yutaka Kawahara, Masatoshi Shioya, Sen'i Gakkaishi, 60(4), 105-111(2004), Carbonization Behavior of Silk．
    4.Hiroyuki Wakisaka, Hajime Miyake, Yutaka Kawahara, Preparation of activated carbon from beer lees and influence of protein fraction on activation process, TANSO, No.218, 192-196 (2005).
    5.Yutaka Kawahara, Masayoshi Izumoto, Goro Nishikawa, Hiroyuki Wakisaka, Norio Iwashita, Kazuyoshi Yamamoto, Noboru Ishibashi, Carbonization Behavior of Reed Grass and Production of Activated Carbon, Sen'i Gakkaishi, 62(10), 242-244(2006).
    6.Goro Nishikawa, Masatoshi Shioya, Norio Iwashita and Yutaka Kawahara, Carbonization behavior of L-tryptophan and gluten, Journal of Materials Science, 42(6), 2076-2080(2007).
    7.Yutaka Kawahara, Kazuyoshi Yamamoto, Hiroyuki Wakisaka, Kaori Izutsu, Masatoshi Shioya, Toshiaki Sakai, Yutaka Takahara, Noboru Ishibashi, Carbonaceous adsorbents produced from coffee lees, Journal of Materials Science, Volume 44, 1137-39(2009).
    8.Kazuyoshi Yamamoto, Yutaka Kawahara, Masatoshi Shioya, Noboru Ishibashi, Utilization of triacetylcellulose waste for the production of carbonaceous adsorbents, Journal of Polymers and the Environment, 20(2), 626-630 (2012).
    9.Noboru Ishibashi, Kazuyoshi Yamamoto,Hiroyuki Wakisaka, Yutaka Kawahara, Influence of the hydrothermal pre-treatments on the adsorption characteristics of activated carbons from woods, Journal of Polymers and the Environment, 22(2), 267-271(2014).

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    Shrinkproof and Reinforcing Effects of Duck Feather Keratin Hydrolysate on the Conservation Treatment of Archaeological Waterlogged Wood

    Abstract

    Shrinkproof and reinforcing effects of duck feather keratin hydrolysate on the conservation treatment of archaeological waterlogged wood were investigated. The bulking effect, i.e. the shrink proof index was enhanced through the impregnation of cell walls with duck feather hydrolysate and sodium acetate derived from neytralization process in the preparation of pH 7 duck feather hydrolysate solution. The reinforcement of cell walls seems to be brought about through the structural modification of duck feather hydrolysate to beta sheet form by acetic acid in the treatment bath. The good affinity between lignin, main component of biodegraded waterlogged wood, and duck feather keratin is also effective for the reinforcement of cell walls. In addition, this treatment is effective for the protection of treated wood against UV rays. The reinforcement effect of keratin hydrolysate is promising for certain kinds of vegetable fibers.

    Shrinkproof Effect




    The treted wood(right→) retained its shape whereas the large shrinkage was observed for untreated wood(←left).

    Fig.1 Appearance of archaeological waterlogged wood specimens dried: a, untreated, and the specimens treated with duck feather solutions of b, 10%, c, 20%, d, 30% and e, 40%.





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    Reinforcing Effect




    ←Fig.2 Compressive stress-strain curves of arhcaeological waterlogged wood specimens.



    →Fig.3 Scanning electron micrograph of the cross-section for archaeological waterlogged wood specimens treated with duck feather hydrolysate. Scale bar = 10μm.


    Biodegraded cell walls of archaeological waterlogged wood are directly reinforced by the keratin hydrolysate because we can distinguish space between cell walls and settled chemicals. It is not merely based on the impregnation mechanism.



    Visit to National Museum of Denmark
    7th September 2007





































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    Articles Published

    1.Rie Endo, Yutaka Kawahara, Shrinkproof and Reinforcing Effects of Duck Feather Hydrolysate on the Treatment of Archaeological Waterlogged Wood, Sen'i Gakkaishi, 60, 372-376(2004).
    2.Rie Endo, Yutaka Kawahara, Kaeko Kamei, Conservation Finishing for Archaeological Waterlogged Wood Using Feather Hydrolysate, Sen'i Gakkaishi, 60, 125-129(2004).
    3.Yutaka Kawahara and Rie Endo, Chemical Finishing of Bast Fibers and Woods Using Hydrolyzed Keratin from Waste Wool or Down, Textile Research Journal, 74(2), 93-96 (2004).
    4.Rie Endo, Kaeko Kamei, Ikuho Iida and Yutaka Kawahara, Dimensional stability of waterlogged wood treated with hydrolyzed feather keratin, Journal of Archaeological Science, Volume 35, 240-1246(2008).
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    New Vegetable Fibers

    Retting Technology

    The vegetable fibers should be used more widely in the industrial fields. European and Japanese motor companies use the plastics reinforced by vegetable fibers for the interior parts. To retain the mechanical properties of vegetable fibers, the retting is the most important and critical process. The figures show the surface of retted fibers. To elevate the smoothness of fibers, the concentration of alkali in retting bath must be controlled over than 4%. However, the mechanical properties tend to be affected by the attack of alkali to the middle lamella between the fibrous cells constructing the fiber.










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    Aesthetic Luster

    The enzymatic retting of kudzu fibers were performed using several commercial enzymes and the effects on the retting were compared from the viewpoints of the smoothness for the surface of fibers as well as mechanical properties. The commercial enzymes used could be classified into two types, i.e. cellulase-type and pectinase-type. For cellulase-type, the enzymatic decomposition occurred almost topochemically because of the cooperation of the cellulase with high activity and the retting was fully achieved suppressing the damage to the intercellular matrix (middle lamella) by pectinase. For pectinase-type, the decomposition predominately occurred in the middle lamella that joints the adjacent fibrous cells. Therefore the tensile properties of retted fibers were fairly lowered. In the retting of kudzu fibers, a topochemical process is promising to produce the fibers with excellent luster retaining tensile properties.

    Relative luster of kudzu fibers retted with enzymes. Incident beam angle was set at 15°from horizontal and regular reflection was measured along to the fiber axis. ■viscozyme L, ■ ultrazyme 100G, ■ pectinase G, ■ pectinase PL, ■ hemicellulase 90, ■ traditionalwater-retting (preboild) and ■ traditionalwater-retting (normal).





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    Articles Published

    1.Yutaka Kawahara, Rie Endo, Goki Kawashita, Influence of Ferrous Contaminations or Keratin Treatments on the Degradation of Bast Fibers by Irradiation with Ultraviolet Rays, Sen'i Gakkaishi, 58(8), 314-316(2002).
    2.Yutaka Kawahara, Yusuke Kawata, Rie Endo, Hideaki Minami, Shigenori Nishiuchi, Destruction of Middle Lamella in Jute Fibers by Hydrothermal Treatment, Sen'i Gakkaishi, 61, 142-145(2005).
    3.Yutaka Kawahara, Takayuki Sakiyama, Rie Endo, Tensile Properties for Jute Fibers Treated with Methacrylamide, Sen'i Gakkaishi, 61, 138-141(2005).
    4.Yutaka Kawahara, Keiichi Tadokoro, Rie Endo, Masatoshi Shioya, Yukio Sugimura, Toshiharu Furusawa, Chemically Retted Kenaf Fibers, Sen'i Gakkaishi, 61, 115-117(2005).
    5.Yutaka Kawahara, Tomoyuki Tsuda, Hideaki Minami, Shigenori Nishiuchi, and Rie Endo, Enzymatic Retting of Kudzu Fibers, Journal of Applied Polymer Science, Vol.106, Issue 4, 2759-2762 (2007).
    6.Akihiro Nishimura, Hisato Katayama, Yutaka Kawahara, Yukio Sugimura, Characterization of kenaf phloem fibers in relation to stem growth, Industrial Crops and Products, 37(1), 547-552 (2012).

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    Viscoelastic Changes through s-CO2 Treatments and Shish Kebab Structure Observed for Polyester

    Peculiar Viscoelastic Changes for the High-speed-spun PET Fibers Measured after s-CO2 Treatment

    The peak intensity of loss modulus was a little weakened and the position was shifted to the higher temperature side. Such viscoelastic changes is due to binding of amorphous chains by the imperfect small crystallites generated in amorphous regions. Shish kebab structure propagated the stabilizing effects of amorphous chains by the imperfect small crystallites generated in amorphous regions along the fiber axis. Then, the storage modulus increased.

    Fig.1 Temperature dependence of dynamic storage modulus E’and loss modulus E”for HSS (6km/min) fiber: ○, control; ●, s-CO2 treared.(Kawahara, Y., Kamo, M., Yamamoto, K., Ogawa, S., Terada, D., Kikutani, T., Tsuji, M., Oligomer Deposition on the Surface of PET Fiber in Supercritical Carbon Dioxide Fluid, Macromol. Mater. Eng., 291, 11-15 (2006)).
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    Shish-kebab Structure in an Uniaxially Oriented PBT Thin Film



    Fig.2 Each of the recognized stacked-lamellar structures in uniaxially oriented thin films of poly(butylene terephthalate) is assigned to a shish-kebab structure or a part of it (Yoshioka T, Tsuji M, Kawahara Y, Kohjiya S, Manabe N, Yokota Y. Polymer 2005; 46:4987).



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    Articles Published

    1.Yutaka Kawahara and Takeshi Kikutani, Journal of Macromolecular Science Physics, B39, 561-567(2000). Diffusion of Organometallic Compounds into High-speed Spun Poly(ethylene terephthalate) Fiber in Supercritical Carbon Dioxide Fluid.
    2.Yutaka Kawahara, Taiyo Yoshioka, Masaki Tsuji, Masayoshi Ohara, Shinzo Kohjiya, and Takeshi Kikutani, Journal of Macromolecular Science Physics, B39, 701-710(2000). Transmission Electron Microscopic Investigation of the Morphology of High-Speed Spun Poly(Ethylene Terephthalate) Fibers.
    3.Yutaka Kawahara, Takeshi Kikutani, and Masaki Tsuji, AATCC Review, Influence of Interfibrillar Voids and Surface Morphology on Dyeing High-Speed Spun PET Fibers, 1(2), 34-38(2001).
    4.Yutaka Kawahara, Taiyo Yoshioka, Kazuaki Sugiura, Satoshi Ogawa, and Takeshi Kikutani, Journal of Macromolecular Science Physics, B40(2), 189-197(2001). Dyeing Behavior of High-Speed Spun Poly(Ethylene Terephthalate) Fibers in Supercritical Carbon Dioxide.
    5.Yutaka Kawahara, Kazuaki Sugiura, Satoshi Ogawa, Takeshi Kikutani, Sen'i Gakkaishi, 57, 220-223(2001), Structure of Poly(ethylene terephthalate) Fibers Treated in Supercritical Carbon Dioxide Fluid.
    6.Yutaka Kawahara, Takeshi Kikutani, Kazuaki Sugiura and Satoshi Ogawa, Coloration Technology, 117(5), 266-269(2001). Dyeing behaviour of poly(ethylene terephthalate) fibres in supercritical carbon dioxide.
    7.Yutaka Kawahara, Taiyo Yoshioka, Masaki Tsuji, Takeshi Kikutani, Kazuaki Sugiura, and Satoshi Ogawa, Morphology of High-speed Spun Poly(ethylene-2,6-naphthalene dicarboxylate) Fiber and its Structural Changes by the Treatment in Supercritical Carbon Dioxide Fluid, J. Macromol.Sci.-Phys., B41(1), 177-184(2002).
    8.Yutaka Kawahara, Masatoshi Shioya, and Takeshi Kikutani, Swelling Behavior of High-speed Spun Poly(ethylene terephthalate) Fibres, J. Macromol.Sci.-Phys., B41(2), 397-406(2002).
    9.Taiyo Yoshioka, Masaki Tsuji, Yutaka Kawahara, Shinzo Kohjiya, and Takeshi Kikutani, Permanganic Etching of Poly(ethylene terephthalate) Fibers, Sen'i Gakkaishi, 58(7), 268-272(2002).
    10.Douhiko Terada, Yutaka Kawahara, Takeshi Kikutani, Sen'i Gakkaishi, 58(9), 342-345(2002), Structural Analysis for PET Fiber using Laser Raman Microprobe Spectroscopy.
    11.Taiyo Yoshioka, Masaki Tsuji, Yutaka Kawahara, Shinzo Kohjiya, Takeshi Kikutani, and Hiraku Ito, A Study on the Fibrillar Structure Formed in Poly(ethylene naphthalate) Fibers, Ann. Rep. Res. Inst. Chem. Fib. , Jpn., 59, 1-9(2002).
    12.Douhiko Terada, Yutaka Kawahara, Sen'i Gakkaishi, 59(10), 385-391(2003), Structural Modification of Polyester Shin-Gosen by the Treatment in Supercritical Carbon Dioxide Fluids.
    13.Taiyo Yoshioka, Masaki Tsuji, Yutaka Kawahara, and Shinzo Kohjiya, Morphological study by TEM on uniaxially oriented thin films of PET, PEN and their blends, Polymer, 44, 7997-8003(2003).
    14.Douhiko Terada, Yutaka Kawahara, Takeshi Kikutani, Sen'i Gakkaishi, 60(12), 357-364(2004), Structura Modification of Polyester Fibers in Supercritical Carbon Dioxide Fluid.
    15.Yukiko Furuhashi, Atsushi Nakayama, Teruo Monno, Yutaka Kawahara, Hideki Yamane, Yoshiharu Kimura, Tadahisa Iwata, X-Ray and Electron Diffraction Study of Poly(p-dioxanone), Macromol.Rapid. Commun. , 25, 1943-1947(2004).
    16.Taiyo Yoshioka, Masaki Tsuji, Yutaka Kawahara, and Shinzo Kohjiya, Morphological Study on Uniaxially Oriented Thin Films of Poly(butylenes terephthalate)[PBT], Ann. Rep. Res. Inst. Chem. Fib., Jpn., 61, 33-39(2004).
    17.Taiyo Yoshioka, Masaki Tsuji, Yutaka Kawahara, Takeshi Kikutani and Shinzo Kohjiya, Internal fine structures in the high-speed-spun fibers of poly(ethylene 2,6-naphthalene dicarboxylate), Polymer, 46, No.6, 1886-1892(2005).
    18.Taiyo Yoshioka, Masaki Tsuji, Yutaka Kawahara, Takeshi Kikutani and Shinzo Kohjiya, Internal fine structures in the high-speed-spun fibers of poly(ethylene 2,6-naphthalene dicarboxylate), Polymer, Volume 46, Issue 14, 27 June 2005, Pages 5429-5432.
    19.Taiyo Yoshioka, Masaki Tsuji, Yutaka Kawahara, Shinzo Kohjiya, Norio Manabe and Yoshimitsu Yokota, Morphological study by TEM on uniaxially oriented thin films of PBT, Polymer, 46, No. 14, 27 June 2005, pp. 4987-4990.
    20.Yutaka Kawahara, Masaki Kamo, Kiyoshi Yamamoto, Satoshi Ogawa, Douhiko Terada, Takeshi Kikutani, Masaki Tsuji, Oligomer Deposition on the Surface of PET Fiber in Supercritical Carbon Dioxide Fluid, Macromol. Mater. Eng., 291, 11-15 (2006).
    21.Yutaka Kawahara, Tomohiro Kurooka, Dohiko Terada, Changes in Tensile Properties for the PET Films by the Treatment in Supercritical Carbon Dioxide Fluid, Journal of Materials Science, Volume 43, 6866-6871(2008).
    22.Yutaka Kawahara, Satoshi Naruko, Atsushi Nakayama, Ming-Chien Wu, Eamor M. Woo, Masaki Tsuji, Morphological studies on single crystals and nanofibers of poly(heptamethylene terephthalate), Journal of Materials Science, Volume 44, 4705-4709(2009).
    23.Taiyo Yoshioka, Yutaka Kawahara, Takeshi Kikutani, Masaki Tsuji, Stacked-Lamellar Structure in High-Speed Spun PET Fibers as Revealed by TEM, J. Macromol. Sci., Part B, Phys., 49, 155-162 (2010).
    24.Yutaka Kawahara, Atsushi Nakayama, Masatoshi Shioya, Masaki Tsuji, Hideki Yamane, Tadahisa Iwata, Supramolecular Morphology of Two-Step, Melt-Spun Poly(dioxanone) Fibers, Journal of Materials Science, Volume 47, Issue 4 (2012), Page 1887-1892.
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    "Etached surface of HSS PET fibers"

    TEM observation for high speed spun PET fibers revealed that the fiber takes stacking lamella structure and the stacking direction is declined against fiber axis by ca. 35 degree and the long period is in the range of 10-30 nm. These results almost coincide with the model structure proposed by Shimizu et al.

    Fig. (a) Bright-field image for a replica of an etched HSS-PET fiber (spun at 6km/min). Image (b) was enlarged with higher contrast from the white rectangular portion in image (a).

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    Hello! My name is "KURO-5!"

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    Party in lab. (Nov., 2011)




































    OB meeting with my graduate students from Kyoto Institute of Tech. (Mar., 2011 in Kyoto)








































    Philipps University, Marburg, Germany,
    Dr. A. Schaper on the top of Mt. TSUKUBA！(Mar., 2009)



    Mr.& Mrs.Schaper in Yokohama(Apr., 2013)



































    Visiting an old Korean temple with my friend in Busan(Nov.,2006)


























    My friend’s garden in Melbourne, Australia(Nov., 2005)



    Welcome to Japan! Dr. Cao (National Museum in Ueno, May, 2013)







































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