| 高分子 Vol.64 No.6 |
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| 展望 COVER STORY: Highlight Reviews |
| プラスチックの破壊 Fracture of Plastics |
栗山 卓 Takashi KURIYAMA |
| ＜要旨＞ プラスチックの主な破壊現象である、ぜい性破壊、延性破壊、疲労破壊およびクリープ破壊を示した。さらに、単一クラック周りの力学を扱う破壊力学視点から、それらの破壊現象と、クレイズ変形およびせん断降伏変形のかかわり方について解説を行った。 Keywords: Crazing / Shear Yielding / Crack / Brittle / Ductile / Fracture Toughness / Toughening |
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| ゴム破壊における弾性－粘性転移現象 Elastic-Viscous Transition in Tear Fracture of Rubbers |
深堀 美英 Yoshihide FUKAHORI |
| ＜要旨＞ ゴムの引裂き破壊で起こる“弾性－粘性転移”を説明したい。この現象はガラス転移点付近で起こるき裂成長速度の不連続変化（速度ジャンプ）を指しており、ひずみエネルギー解放率と破壊抵抗力（靭性）のせめぎ合いによってもたらされる。 Keywords: Cross-Linked Rubber / Elastic-Viscous Transition / Brittle Fracture / Ductile Fracture / Stick-Slip Motion / Velocity Jump |
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| ゲルらしい壊れ方とは何か What are Characteristics of Gel Fracture |
田中 良巳・松田 昂大 Yoshimi TANAKA, Takahiro MATSUDA |
| ＜要旨＞ ゲルは巨視的には柔らかな固体であると同時に分子鎖スケールでは溶液的である。本稿では、ゲルと同じく高分子網目物質であるゴムの破壊強度の説明のために導入されたLake-Thomasの議論がゲルの場合にどう修正されるか、を考察しつつ固体性と溶液性が交錯する「ゲルらしい破壊の仕方」について考える。 Keywords: Gels / Fracture / Strength |
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| 粘着・剥離の動力学 Dynamics of Adhesion and Debonding |
山口 哲生 Tetsuo YAMAGUCHI |
| ＜要旨＞ 粘着・剥離は、おもにやわらかい物質の界面で起こる、一種の破壊現象である。本稿ではとくに、ゆるく架橋された粘弾性体である粘着剤を被着体から剥がすときに生じる巨大変形の動力学を通して、粘着・剥離とはどのようなものであるかを説明する。 Keywords: Adhesion / Debonding / Cavitation / Fibrillation / Dynamics / Pressure Sensitive Adhesives |
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| トピックス COVER STORY: Topics and Products |
| 可逆架橋による高分子ゲルの高強度化 Mechanical Properties of Self-Recovery Tough Gels with Permanent and Reversible Crosslinks |
眞弓 皓一・成田 哲治・Costantino CRETON Koichi MAYUMI, Tetsuharu NARITA, Costantino CRETON |
| ＜要旨＞ We have studied the linear viscoelasticity, large deformation behaviours, and fracture properties of self-recovery dual crosslink gels having covalent crosslinks and reversible crosslinks. We have developed model dual cross-link gels with covalent and reversible bonds by the complexation of chemically cross-linked poly(vinyl alcohol) (PVA) gels with borate ions. The PVA dual crosslink gels are good model systems to investigate quantitatively the relationship between the breaking/healing dynamics of the breakable crosslinks and the macroscopic mechanical properties in large strain because they have a well-defined life time of the reversible bonds observed by liner rheology. We have proposed a physical model for the stress-strain relation of the dual crosslink gels considering the effect of the breaking/healing dynamics. The dynamic reforming of the reversible network structure during deformation improves the mechanical toughness and stretchability of the dual crosslink gels. Keywords: Polymer Gels / Reversible Crosslink / Rheology / Toghness |
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| 高圧水素シール用ゴム・エラストマー材料 Rubbers and Elastomers for High-pressure Hydrogen Seal |
西村 伸 Shin NISHIMURA |
| ＜要旨＞ High-pressure hydrogen gas seal is one of key technologies for materialization of hydrogen energy system. It is important to understand the durability of high-pressure gas seal. According to the results of O-ring fracture, we found the three fracture modes, internal fracture of rubbers originated from inflation of dissolved hydrogen, referred as “Blister Fracture”, external fracture in terms of volume inflation of rubber in the O-ring gland, referred as “Overflow Fracture” and “Buckling Fracture” Ethylene–propylene rubber (EPDM) and acrylonitrile–butadiene rubber (NBR) composites filled with carbon black, silica, and unfilled composites were exposed to high-pressure hydrogen gas. The blister fracture of composites with silica was less pronounced, irrespective of the hydrogen pressures. This can be attributed to their lower hydrogen content and higher strength than the others. Understanding the effect of decompression rate on the blister fracture is also important. The numerical analysis of blister fracture behavior during decompression process is undergoing. Keywords: Hydrogen / O-ring / Ethylene Propylene Rubber / Acrylonitrile Butadiene Rubber Carbon Black / Silica / Blister Fracture / Gas Seal |
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| グローイングポリマー Polymer Science and I: A Personal Account |
| 『オリジナリティー』への挑戦 Challenge for “Originality” |
井澤 浩則 Hironori IZAWA |
| ＜要旨＞ Originality is one of the important factors in my research. Although I have not achieved yet a confident “Izawa's model”, I would advance step by step to launch it. Some impressive stories, which were turning points for me, are described here. |
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| 高分子科学最近の進歩 Front-Line Polymer Science |
| 高分子電解質ブラシとイオン種特異性 Polyelectrolyte Brush and Specific Ion Effect |
松岡 秀樹 Hideki MATSUOKA |
| ＜要旨＞ Rescent research on polyelectrolyte brushes and thermosensitive poly(NIPAm) brushes is reviewed in this paper, especially regarding the specific ion effects on their nanostructure and responsitivity. They cannot simply be explained by the traditional Hofmeister concept, but require novel ideas on the characteristics of each cation and anion, especially on the spcific interaction between ions and polymers. Keywords: Polyelectrolyte Brush / Specific Ion Effect / Hofmeister Series / Poly(N-isopropylacrylamide) / Betaine Brush / Zwitterion / Polyampholytes / ζ-Potential |
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