松田 聡

Room temperature ionic liquids (ILs) are the appealing research target as electrolytes for lithium batteries. The cation and anion structure of ILs influences their physical and chemical properties. In this study, an electron-donating branched substituent was introduced into imidazolium cations to promote charge delocalization and to improve the reduction stability of ILs. The ILs with branched substituent group at the third position of imidazolium cation, 1-allyl-3-isobutylimidazolium bis(fluorosulfonyl)amide ([AB(iso)Im][FSA]) and 1-allyl-3-tert-butylimidazolium bis(fluorosulfonyl)amide ([AB(tert)Im][FSA]), exhibited lower cathodic potential (-2.54 and -2.79 V vs. Fc/Fc(+), respectively). [AB(iso)Im][FSA] and [AB(tert)Im][FSA] showed sufficiently high ionic conductivity (4.85 and 3.66 mS/cm at 298 K, respectively), although the viscosity increased with the introduction of bulky branched substituent. Lithium secondary batteries composed of electrolytes using [AB(iso)Im][FSA] and [AB(tert)Im][FSA] showed stable charge-discharge behavior. (C) The Author(s) 2022. Published by ECSJ.

© 2020 Elsevier Ltd The fracture toughness and fracture process of second generation acrylic (SGA) adhesive joints were investigated in detail using tapered double cantilever beam (TDCB) tests. The distribution of granular elastomer with a size of ca. 150 nm in the bulk specimen by transmission electron microscopy (TEM) observation was similar to the distribution of cavitation determined by scanning electron microscopy (SEM) observation of the fracture surface. A mechanism was proposed for the role of the elastomer and acrylic phase in the cohesive failure process of SGA. A dimple, which is evidence of ductile fracture, was observed on the fracture surface. The relationships between the size of dimples, their number and energy release rate were clarified. An understanding of the proposed failure mechanisms is useful for constructing a numerical model for stress analysis and explaining the fracture phenomenon.

© 2018 John Wiley & Sons, Ltd. Carbon black (CB) particles were employed as a reinforcing filler in carboxyl-terminated butadiene acrylonitrile rubber (CTBN)/epoxy resin (diglycidyl ether of bisphenol-A (DGEBA))/aromatic diamine (diamino diphenyl methane (DDM)) network polymer blends. The strength, modulus, and ability to absorb impact energy of the resulting composites were evaluated. The aim of this work was to determine the effects of interfacial interactions between components, and processing conditions (especially temperature) on mechanical properties. The application of high temperatures during the kneading process resulted in strong interfacial interactions between the CB particles and the CTBN. The formation of strong bonds at the CB/CTBN interfaces during kneading was the key factor in obtaining high strength and high impact energy absorbance. The composites also exhibited good adhesive strength during both shear and peel stress tests.

Delamination crack growth behavior under mode II cyclic loading was investigated with interlayer-toughened CFRP laminate, T800H/3900-2. Fatigue tests under a constant maximum energy release rate showed that the growth rate was independent of the crack length. Then, load-shedding tests were carried out under various stress ratios. The fatigue crack growth resistance of the interlayer-toughened CFRP was higher that of conventional CF/epoxy. The crack growth rate under various stress ratios was well correlated to the stress intensity range near the threshold region. Thus, the mechanism of fatigue fracture under mode II loading is completely different from that under mode I loading. Fractographic observation showed that the fatigue fracture occurred on the principal shear stress plane. Large hackle patterns which are typical for static mode II tests were not observed under fatigue loading. A mesoscopic fracture model was proposed to explain the microscopic observation and the stress ratio dependence.

© 2019 by the authors. In this work a cycloaliphatic amine-cured epoxy (EP) resin was modified by micron-scale rubber particles (RP). Nominal RP, in sizes of 200 and 600 μm respectively, were produced using worn truck tires and ultra-high-pressure water jet cutting. The RP were dispersed into the EP resin using different mixing techniques (mechanical, magnetic, and ultrasonic stirring) prior to the introduction of the amine hardener. The dispersion of the RP was studied using optical light microscopy. A longer mixing time reduced the mean size of the particles in the EP compounds. Static (tensile and flexural), dynamic (unnotched Charpy impact), and fracture mechanical (fracture toughness and strain-energy release rate) properties were determined. The incorporation of the RP decreased the stiffness and strength values of the modified EPs. In contrast, the irregular and rough surface of the RP resulted in improved toughness. The fracture toughness and strain-energy release rate were enhanced up to 18% owing to the incorporation of 1% by weight (wt%) RP. This was traced to the effects of crack pinning and crack deflection. Considerably higher improvement (i.e., up to 130%) was found for the unnotched Charpy impact energy. This was attributed to multiple cracking associated with RP-bridging prior to final fracture.

© BME-PT. Acrylic polymers have high potential as matrix polymers for carbon fiber reinforced thermoplastic polymers (CFRTP) due to their superior mechanical properties and the fact that they can be fabricated at relatively low temperatures. We focused on improving the interfacial adhesion between carbon fibers (CFs) and acrylic polymers using several functional monomers for co-polymerization with methyl methacrylate (MMA). The copolymerized acrylic matrices showed good adhesion to the CF surfaces. In particular, an acrylic copolymer with acrylamide (AAm) showed high interfacial adhesive strength with CFs compared to pure PMMA, and a hydroxyethyl acrylamide (HEAA) copolymer containing both amide and hydroxyl groups showed high flexural strength of the CFRTP. A 3 mol% HEAA-copolymerized CFRTP achieved a flexural strength almost twice that of pure PMMA matrix CFRTP, and equivalent to that of an epoxy matrix CFRP.

オリゴマーの平均分子量が同じで分子量分布の異なるエポキシ樹脂を作製し，微細構造および力学特性に及ぼす影響を調べ，これらの関係について検討した。主剤に平均分子量の異なる4 種類のビスフェノールA 型ジグリシジルエーテルを用いてさまざまな配合比で混合し，平均分子量が同じで分子量分布が異なる4 組成のブレンド樹脂を作製した。作製した樹脂について，微細構造観察および力学特性評価を行った。動的粘弾性試験の結果，分子量分布が広くなるほどガラス転移領域が広くなり，材料内部の架橋密度差が大きくなることが分かった。架橋密度差の拡がりとともに不均質構造のサイズも大きくなった。特に，分子量分布がもっとも広い系では，硬化時に反応誘起型相分離が生じたことが分かった。曲げ弾性率，曲げ強度は，分子量分布およびそれに伴う内部構造変化の影響を受けなかったが，破壊靭性値は分子量分布が広くなるにつれて高くなった。微細構造モデルを提案し，そのモデルを用いて破壊靭性向上のメカニズムについて考察した。

© 2014 The Electrochemical Society. To make larger capacity of charge-discharge of lead-acid batteries at high pressure after the initial formation of Plante-type electrodes, we studied the effect of high pressure on prolonged life testing. Electrode life was evaluated by determining the time of detachment of active crystals (Pb, PbOx and PbSO4) or the drop in ampere-hour efficiency during the charge-discharge cycle. Prolonged life testing, active crystals (Pb, PbOx and PbSO4) on the electrodes used in charge-discharge cycles at atmospheric pressure were easily detached when the electric current was increased to 2.7 mA/cm2, but the electrodes used at 100 MPa remained very tough until 8.0 mA/cm2 was reached. To increase the electric capacity of electrodes (i.e. in the second formation process), long-term charge-discharge was performed at a high electric current (5.3 mA/cm2). Faster second formation of electrodes at this high current was impossible at a charge of 3.6 As under atmospheric pressure, but it was possible at 6 As and 100 MPa.

© 2015 The Society of Materials Science, Japan. Crash safety of a vehicle is based on impact energy absorbed by crashing the structure in a situation that a cabin is protected. Side impact is extremely dangerous for passengers of vehicles. Energy absorption capabilities of the vehicle in side impact are low because there is little room for large deformation of the safety element to absorb impact energy. On the other hand, weight reduction of the vehicle is also important for the fuel efficiency. The purpose of this study is to develop a light and effective energy absorbing member for side impact. In this paper, an energy absorbing tubular member made by a combination of a thin-walled circular tube and a thin-walled square tube was proposed. The effect of the cross-sectional shape of the tubular member on energy absorption capacities under bending impact was investigated by the experiment and the analysis of the finite element code LS-DYNA. From the obtained results, bending strength decreased significantly when the cross section of the member which was subjected to impact bending load was crushed in flat shape. Therefore, energy absorption capacities were able to be improved by preventing flattening deformation of the cross section. Energy absorption capacities of the tubular member were able to be improved by changing its cross-sectional shape without increasing of the weight.

© 2015 International Committee on Composite Materials. All rights reserved. Within several candidates of matrix polymers for carbon fiber reinforced thermoplastic composites (CFRTP), acrylic polymers have high potential in terms of low-temperature processing. We focused on the improvement in the interfacial adhesive properties between CFs and the acrylic polymers using several functional monomers for the co-polymerization with methyl methacrylate (MMA). Several functional acrylic monomers were co-polymerized with the MMA, and applied as the matrix polymers of the acrylic CFRTPs. It was observed that the copolymer matrices well-adhered to the surfaces of CFs, compared to the pure PMMA. The copolymer with acrylamide (AAm) indicated higher interfacial adhesive strength than that with hydroxyethyl acrylate (HEA). The hydroxyethyl acrylamide (HEAA) copolymer having both amide groups and hydroxyl groups showed very high adhesive strengths to CFs, which resulted in the high flexural strengths of the CFRTPs. The flexural strength of the pure PMMA CFRTP was 450 MPa. On the other hand, the co-polymerized acrylic matrices gave the increase in the flexural strength for the CFRTPs. Especially, the 3mol% HEAA copolymer achieved the two-fold flexural strength (900 MPa) on the acrylic CFRTP. The strength was equivalent level to the epoxy CFRP. The fatigue resistance of the HEAA copolymerized CFRTPs were also evaluated, in relation to the interfacial adhesive strength.

© 2015 International Committee on Composite Materials. All rights reserved. Epoxy resins are utilized in various industrial areas as adhesives and matrix of composite materials because of the higher stiffness, strength and heat resistance. Toughening with rubber particles is one of the most popular method to enhance the fracture toughness. For the structure uses, the fatigue resistance is very important property as well as the static mechanical properties. In this study the effect of molecular weight between crosslinks (crosslink density) on the fatigue crack propagation properties of rubber-toughened epoxy resin. Several DGEBA epoxy resins with different average molecular weight were used in this study. Core shell rubber (CSR) particles, the diameter of 100nm, were well dispersed in the epoxy. The fracture toughness of Core Shell Rubber-modified epoxy monotonously enhanced with increasing molecular weight between crosslinks, and the effect of core-shell rubber became larger as the molecular weight between crosslink increased. On the other hand, the fatigue threshold had a peak against molecular weight between crosslinks. Whereas there is positive effect of core shell rubber in fatigue resistance for molecular weight between crosslink of 1440g/mol, the fatigue threshold of the core shell rubber modified epoxy is lower than that of unmodified one for molecular weight between crosslinks of 3040g/mol. TEM observation from the side surface of the crack tip revealed that the size of the plastic deformation zone was well related to the fatigue resistance. The core shell rubber particles enhanced the shear plastic deformation region at the crack tip for molecular weight between crosslinks of 1440g/mol, and the particles largely lowered the deformation region. These results was caused by the deformation ability of the epoxy resin under plane-stress state.

Fatigue resistance of toughened epoxy resins with preformed polymer particles were studied in terms of the fatigue threshold and the fatigue crack propagation (FCP). The toughening modifiers were polyamide-12 (PA12) and core-shell rubber (CSR). The PA12 toughened epoxy achieved higher stress intensity factor range (AK) than the pure epoxy, irrespective of the molecular weight between cross-links (Mc) of the epoxy matrices. The crack bridging of the PA12 particles was the major mechanism of the fatigue resistance. Meanwhile, the fatigue behavior of the CSR / epoxy resins depended on the Mc. The whole FCP curve of the CSR / epoxy with low Mc was in the high AK. However, the fatigue threshold of the CSR / epoxy with high Mc was in the lower AK than that of the pure epoxy. The plastic deformation of the epoxy matrix with high Mc was localized, which decreased the fatigue resistance.

異種高分子多層成形体において，層間の反応をもたらす官能基量が剥離接着強さに与える影響について検証した。まず，エチレン—グリシジルメタクリレート(GMA)共重合体(PE－GMA)とポリプロピレン(PP)との多層積層体の剥離接着強さを評価した。その際，同じPE－GMAシートに対し，PPシート表面に酸素プラズマ処理を施すことで官能基量を変え，多層積層体の剥離接着強さとの関係を評価した。また，剥離面のSEM観察を行い，剥離接着強さの発現機構について考察した。反応サイト数（化学結合数）の増加に伴い,PE/PP界面接着性は向上する｡その結果，力学的拘束を受ける界面近傍のPEに空洞化を伴う膨張的塑性変形が発生することがわかった。界面接着向上により増加したPEのバルク塑性変形は，PE－PP間の剥離接着強さ向上をエネルギー的に説明する因子として重要である。

Peel adhesive strengths of multi-layered laminates composed of two polypropylene (PP) sheets and an inserted polyethylene (PE) layer (the middle layer) between the PP layers were evaluated. PE-glycidyl methacrylate (GMA) copolymers and a maleic-anhydride grafted PP (MAPP) were compared to the PE homopolymer and the PP homopolymer. The peel adhesive strength of PE-GMA/MAPP laminates was much higher than that of PE homopolymer/PP homopolymer laminates. Meanwhile, the blends composed of the PE-GMA and three types of PE homopolymer (PE-GMA+LDPE, PE-GMA+MDPE, PEGMA+ HDPE) were formulated as the PE middle layer of the multi-layered laminates. The PE blends had the same amount of glycidyl groups, and the deformation capacity was different in each. Namely, the PE blend of LDPE had higher elongation to break than the PE blend of HDPE. The peel adhesive strength of the multi-layered laminates with the middle layer of the LDPE blend was highest among the three types of laminates with the middle layer of the PE blends. Scanning electron microscopy on the fractured surfaces revealed that the large plastic deformation of the LDPE blended middle layer was responsible for the high energy absorption, and resulted in the high peel strength. © Carl Hanser Verlag GmbH & Co. KG.

New wood-based epoxy resins were synthesized from alcohol-liquefied wood. Wood was first liquefied by the reaction with polyethylene glycol and glycerin. The alcohol-liquefied wood with plenty of hydroxyl groups were precursors for synthesizing the wood-based epoxy resins. Namely, the alcoholic OH groups of the liquefied wood reacted with epichlorohydrin under alkali condition with a phase transfer catalyst, so that the epoxy groups were put in the liquefied wood. The wood-based epoxy resins and the alcohol-based epoxy resins as reference materials were cured with polyamide amine. The glass transition temperature (Tg), the tensile strength, and the modulus of elasticity of the wood-based epoxy resin were higher than those of the alcohol-based epoxy resin. Also, the shear adhesive strength of the wood-based epoxy resin to steel plates was higher than those of the alcohol-based epoxy resins, which was equivalent to the level of petroleum-based bisphenol-A type epoxy resins. The higher Tg of the wood-based epoxy resin than that of the alcohol-based epoxy resin is one of the evidences that the wood-derived molecules were chemically incorporated into the network structures. © 2010 Wiley Periodicals, Inc.

液化溶媒種の異なるアルコール液化木材エポキシ樹脂について，耐熱性および力学物性の関係を調べた。木材液化溶媒として脂肪族アルコールであるポリエチレングリコール（PEG）と芳香族アルコールであるビスフェノールA エチレンオキシド付加物（BPAEO）を比較した。BPAEO は木材液化溶媒として有効であり，PEG と同等以上に木材を液化することが可能であった。BPAEO 液化木材エポキシ樹脂はPEG 液化木材エポキシ樹脂と比べ，高い耐熱性および引張物性を有する。エポキシ樹脂の化学構造中に液化溶媒由来の芳香環構造が導入されたためと考えられる。また，BPAEO 液化木材エポキシ樹脂のバイオマス含有率向上に伴い，T_g および曲げ物性が向上することが分かった。

異種高分子の組み合わせは一般には相溶性や相互の接着性に乏しいため，これらの多層成形体には界面剥離が生じやすく，単一樹脂成形体より脆性・低強度なものになりがちである。回転成形でも同様，ポリエチレン層とポリプロピレン層の2層成形体は，層間剥離が生じる。しかしながら，これら2層の間に，ポリエチレンとポリプロピレンの混合パウダーを中間層として投入することで，剥離強さが著しく向上することを見出した。また，その中間層のポリエチレンの密度を変化させると，剥離強さが変わることが知られた。この中間層の相構造や，剥離表面の観察を行ない，中間層におけるポリエチレンの塑性変形挙動と剥離強さ発現メカニズムについて検証した。

Composites consist of carboxyl-terminated butadiene acrylonitrile rubber (CTBN) / epoxy resin blends and carbon-black (CB) were formulated. The impact-energy absorbability of the composites depended on the kneading temperature of the resin and the CB. Strong interaction at the interface between CTBN and CB particles was the key factor to achieve the high impact-energy absorbability.

Carboxyl-terminated butadiene acrylonitrile (CTBN) rubber/ epoxy (diglycidyl ether of bisphenol-A) / diamino diphenyl methane polymer blends with 60 wt% of CTBN were formulated to evaluate the viscoelasticity and the damping properties. When the blend resins had micro-phase separated morphologies composed of epoxy-rich dispersed phases larger than 500 nm in diameter surrounded by a rubber-rich continuous phase, the loss factors (η) of the steel laminates adhered with the resin significantly depended on the environmental temperature and the resonant frequencies. The resins with epoxy-rich phases smaller than 200 nm in diameter had broad glass-transition temperature range that resulted in the high loss factor (η > 0.1) of the steel laminates in the broad temperature range. Inhomogeneous nano-gel structures with 20-30 nm sizes were observed in more compatible resins by scanning probe microscopy, although appreciable micro-phase separation was detected by none of SEM and TEM. Pulse NMR suggested that the fraction of interfacial phase in the resins increased with increasing the compatibility of the blends. The large interfacial phase in the inhomogeneous nano-gel structures seems to play an important role in the damping mechanisms. ©2008 The Society of Rheology.

Resin coatings and linings are very useful methods for corrosion prevention of steel structure exposed to hot steam or acid liquid. Vapor permeation is one of the most important properties for corrosion resistant coatings. Nano filler dispersion is well known to improve the vapor permeation for the nylon and the other plastic materials, and is expected to reduce the vapor permeation of the coating resin and expand the lifetime of the coating system. The aim of this study is to clear the effect of the nano filler on the vapor permeation property of the vinyl ester resin. One montmorillonite clay and three organophilic clays with different surface treatment were dispersed in the bisphenol vinyl ester resin system. Scanning electron microscopy and optical microscopy revealed that the different surface treatment resulted in the different dispersion characteristic. The vapor permeation of the nanocomposites was measured under 40°C, showing that the nano filler addition reduced the vapor permeation and the nanocomposite with the better dispersion of the clay had the lower permeation rate. The undispersion index, defined as the area ratio of the residual aggregate particles on the surface, showed the fairly good correlation with the permeation rate. The mechanism of the vapor permeation of the nanocomposites was discussed.

The degradation mechanism in molecular order by electron beam (EB) irradiation for three types of thermosetting polymers (bisphenol type vinylester, Novolak-type vinylester and tetra functional epoxy resin) is confirmed by dynamic mechanical thermal analysis (DMTA) and the swelling test in this study. The level of degradation in molecular order is quite high. The same result was observed in Novolak-type vinylester but not in tetrafunctional epoxy resin. The results of the swelling test showed that the cross-linking networks were destroyed by γ- or electron beam irradiation remarkably for both the vinylester resins. For the tetrafunctional epoxy resin, γ- or electron irradiation does not give any effect even in molecular order in high radiation intensity such as 20 MGy. However, the mechanical properties such as bending strength, modulus and fracture toughness of all composites (both vinylester resin and tetrafunctional epoxy resin composites) reinforced by a chopped-strand glass mat or flake-like mica change a little after 20 MGy EB irradiation. © 2007 Curtin University of Technology and John Wiley & Sons, Ltd.

Carboxyl-terminated butadiene acrylonitrile (CTBN) liquid rubber/epoxy (diglycidyl ether of bisphenol-A: DGEBA) / diamino diphenyl methane (DDM) resins, in which CTBN was 60 wt % as the major component, were formulated to evaluate the damping and adhesive properties. In cases where acrylonitrile (AN) was 10-18 mol % as copolymerization ratio in CTBN, the blend resins showed micro-phase separated morphologies with rubber-rich continuous phases and epoxy-rich dispersed phases. The composite loss factors (η) for steel laminates, which consisted of two steel plates with a resin layer in between, depended highly on the environmental temperature and the resonant frequencies. On the other hand, in the case where AN was 26 mol % in CTBN, the cured resin did not show clear micro-phase separation, which means the components achieve good compatibility in nano-scale. This polymer alloy had a broad glass-transition temperature range, which resulted in the high loss factor (η > 0.1) for the steel laminates and excellent energy absorbability as the bulk resin in a broad temperature range. Also the resin indicated high adhesive strengths to aluminum substrates under both shear and peel stress modes. The high adhesive strengths of the CTBN/epoxy polymer alloy originated in the high strength and the high strain energy to failure of the bulk resin. ©2007 Wiley Periodicals, Inc.

Dicyandiamide (DICY)-cured epoxy resins are important materials for structural adhesives and matrix resins for fiber reinforced prepregs. The objective of this study was to examine the mechanical and physical properties as well as the gel structures of the cured resins and discuss the relationships among them. Diglycidyl ether of bisphenol-A (DGEBA) oligomers were chosen as the common chemical structure of the epoxy resins. Four kinds of resin mixtures were formulated using the seven types of DGEBA oligomers having different molecular weight distributions. Three resin formulations having bimodal-type molecular weight distributions were designed to have almost identical rubbery plateau values of the storage modulus in dynamic mechanical analyses after curing, means that they had almost equivalent average crosslink density and basic chemical structure. However, the toughness, ductility, and environmental (heat and solvent) resistance of these three formulations were different. Atomic force microscopy revealed the existence of inhomogeneous nanoscale gel structures in these cured resins. The morphological differences in the gel structures in terms of their size, the connectivity, and the relative magnitude of the heterogeneity would cause the difference in several properties of the DICY-cured epoxy resins. © 2007 Wiley Periodicals, Inc.

This study includes the development of a high heat-resistant FRP whose matrix is T_g-less epoxy resin which can be cured by anionic polymerization with potassium carboxylate salts as initiators. First, various epoxy resins with different chemical structures were evaluated to find an epoxy resin composition which has the least decrease in elastic modulus even at an elevated temperature. As a result, R, which is defined as the ratio of the modulus at 250°C to that at 25°C, exhibited the highest value of 44.5% in the combination of bisphenol A type epoxy resin with a multi-functional glycidyl ether derived from multi-functional phenols. The GFRP whose matrix was this T_g-less epoxy resin composition exhibited high heat-resistant property of R≥80% at 34 vol% of glass fiber content. The FRP had also excellent corrosion-resistance because the chemical structure of its matrix is hard to be hydrolyzed even under acidic or alkaline conditions.

The vacuum assisted resin transfer molding process (VaRTM) is a lower-cost molding method than autoclave molding, and therefore the VaRTM method is preferred for use with structural composites molding. On the other hand, interleaf technology is known as an effective method for improving impact resistance for composite laminates. However, it is impossible to exploit polymer films as interleaf materials when using the VaRTM processing method as resin impregnation in the thickness direction is prevented by the interleaf films. To overcome this problem, the focus of this study was to use non-woven fabric as interleaf materials that were compatible with the VaRTM method and to evaluate their performance. The rate of impregnation by resin for non-interleaved and interleaved FRP was similar. Impact resistance for interleaved FRP had improved by interleaving non-woven fabric. The polyamide non-woven fabric used as interleaves in FRP suppressed crack propagation in the interlaminar region. It is believed that the degree of adhesion of the fabric to the matrix resin is an important factor on the suppression of crack propagation.

カルポキシル基末端ブタジエンニトリルゴム(CTBN)をエポキシ樹脂（ビスフェノールAジグリシジルエーテル:DGEBA)と反応ブレンドした樹脂組成をマトリックス材全体あるいは一部として用いた炭素繊維強化複合材料(CFRP)積層板の衝突エネルギー吸収特性を評価した。ゴムリッチ相とエポキシリッチ相に相分離した樹脂2種および電子顕微鏡で相構造を認識できない相溶性良好な樹脂1種を比較したところ，樹脂のエネルギー吸収性の序列と，これらをマトリックス材としたCF織物積層複合材のエネルギー吸収性の序列は一致した。しかしながら，エネルギー吸収性が高くなるほど樹脂弾性率は低下し，そのCF織物積層複合材にはエネルギー吸収性向上の一方で強度・弾性率が低下するトレードオフ関係が見られた。そこで，上記CTBN/エポキシ反応ブレンド樹脂をCF織物に含浸させたプリプレグを，既存の硬質エポキシマトリックスー方向強化CFプリプレグの層間に挿入したハイブリッド積層複合材を調製したところ，前述の単一マトリックス織物積層複合材よりエネルギー吸収性と弾性率のバランスが向上することが知られた。

国内外の原子力発電所のステンレス鋼製機器の溶接部分において応力腐食割れが問題とされており, その対策として溶接部を熱硬化性の樹脂でカバーする予防保全工法が知られている.従来からあるこれらの施工法では施工に要する時間が長く, 作業者の被曝量が問題とされてきた.そこで我々は溶接線部分を樹脂でカバーする新たな施工法を開発した.この施工法においては, 工場で予め樹脂複合材料のシートを成型加工することにより作業時間の短縮化を実現した.2種類の熱硬化性のエポキシ樹脂およびビニルエステル樹脂がこの施工法に用いられる.本工法においては熱硬化性の樹脂を工場でシートに成型加工するため, 硬化過程における硬度と接着強度の相関を明らかにすれば, 施工後の硬度測定から接着強度の推測が可能になると考えられ, 硬化過程における硬度と接着強度変化を試験した.この結果より, 施工後の硬度測定から接着強度を推測することが可能であると考えられる.

A novel adhesive, consisting of well-formulated epoxy resins and thermally expansive fillers has been developed. The cured adhesive resin showed characteristic viscoelasticity with both the storage modulus higher than 3 GPa in the glassy state under the glass transition temperature (Tg) around 100 °C and the rubbery modulus less than 2 MPa over the Tg. As the results, the joint bonded with the adhesive was strong at ambient temperature under 80 °C and they could be dismantled easily at high temperature due to the expansion force caused by expandable graphite as the fillers. The technique of the dismantlable adhesive joints should be important in terms of material recycling because carbon fiber reinforced plastics (CFRP) has to be separated in the recycling process from the other materials such as steel or aluminum alloy used as parts of automotives, for example.

A Tg-less epoxy resin was easily obtained by curing with ionomer. In this system, the storage modulus did not drop and maintained a high level as if it were in a glassy state even at an elevated temperature of 300°C. Investigation of the curing process for the epoxy resin mixture with ionomer, using DSC and FT-IR, revealed that the curing reaction was initiated from the nucleophilic addition of - COO- to the epoxy group to form an ester linkage, and that the chain propagation subsequently occurred by anionic ring opening polymerization of the epoxy group to form an ether linkage. On the basis of the results, the mechanism of 'Tg-disappearing phenomenon' is also discussed. ©2007 Curtin University of Technology and John Wiley & Sons, Ltd.