The Experts below are selected from a list of 1779 Experts worldwide ranked by ideXlab platform
Yuko Ikeda - One of the best experts on this subject based on the ideXlab platform.
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visualization of nanostructure of soft matter by 3d tem nanoparticles in a natural rubber Matrix
Progress in Polymer Science, 2008Co-Authors: Shinzo Kohjiya, Atsushi Kato, Yuko IkedaAbstract:Abstract In order to visualize the three-dimensional (3D) state of silica or carbon black dispersion in nanocomposites, 3D-TEM, a technique that combines transmission electron microscopy (TEM) with computerized tomography, is used and the results obtained are discussed. This technique is sometimes called electron tomography. The examples presented here elucidate the dispersion of these nanoparticles in a natural rubber (NR) Matrix, which is a technologically very important biomass. It is made clear that such nanoparticles coalesce to form aggregates and they further coalesce to form agglomerates in the Rubbery Matrix. Once 3D-TEM images are established, one can evaluate all structural parameters, depending on the availability of software for each specific purpose. Here, the volume of each component in the composite, the size, the size distribution, the distance between neighboring aggregates, and the aspect ratio of the aggregates, for example, are evaluated as structural parameters. In the case of silica, 3D images of conventional silica and in situ formed silica are compared. The further coalescing of aggregates of both silica and carbon black particles results in the formation of agglomerates, the visualized images of which show that they form a kind of network structure in the rubber. In the case of carbon black, measurement of volume resistivity or electron conductivity reveals that percolation occurs near a volume fraction of 0.17 as a threshold value. Combining the resistivity results with a structural parameter, i.e., the nearest neighbor distance from 3D-TEM images, it is estimated that electrons hop over the rubber phase (which is an insulator), about 3 nm thick, between carbon black aggregates, thereby exhibiting electron conductivity. It is suggested from the results of this study that establishing the correlation between the 3D nanostructures as revealed by 3D-TEM and physical properties can play an important role in advancing the discipline of nanotechnology as an exact science, especially in the area of soft nanocomposites.
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nonuniformity in natural rubber as revealed by small angle neutron scattering small angle x ray scattering and atomic force microscopy
Biomacromolecules, 2007Co-Authors: Takeshi Karino, Yuko Ikeda, Shinzo Kohjiya, Yoritaka Yasuda, Mitsuhiro ShibayamaAbstract:The microscopic structures of natural rubber (NR) and deproteinized NR (DPNR) were investigated by means of small-angle neutron scattering (SANS), small-angle X-ray scattering (SAXS), and atomic force microscopy (AFM). They were compared to those of isoprene rubber (IR), which is a synthetic analogue of NR in terms of chemical structure without any non-rubber components like proteins. Comparisons of the structure and mechanical properties of NR, DPNR, and IR lead to the following conclusions. (i) The well-known facts, for example, the outstanding green strength of NR and strain-induced crystallization, are due not much to the presence of proteins but to other components such as the presence of phospholipids and/or the higher stereoregularity of NR. It also became clear the naturally residing proteins accelerate the upturn of stress at low strain. The protein phases work as cross-linking sites and reinforcing fillers in the Rubbery Matrix. (ii) The microscopic structures of NR were successfully reproduced ...
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visualisation of carbon black networks in Rubbery Matrix by skeletonisation of 3d tem image
Polymer, 2006Co-Authors: Shinzo Kohjiya, Atushi Katoh, Toshiya Suda, Junichi Shimanuki, Yuko IkedaAbstract:The first visualization of nanofiller networking due to association of carbon black in natural rubber is achieved by a transmission electron microscopy combined with computerised tomography (3D-TEM), and the resulted skeleton displays the characteristics of the filler network, which has long been assumed on the percolation behaviour in electron conductivity and on the mechanical behaviours of filled rubbers.
Shinzo Kohjiya - One of the best experts on this subject based on the ideXlab platform.
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visualization of nanostructure of soft matter by 3d tem nanoparticles in a natural rubber Matrix
Progress in Polymer Science, 2008Co-Authors: Shinzo Kohjiya, Atsushi Kato, Yuko IkedaAbstract:Abstract In order to visualize the three-dimensional (3D) state of silica or carbon black dispersion in nanocomposites, 3D-TEM, a technique that combines transmission electron microscopy (TEM) with computerized tomography, is used and the results obtained are discussed. This technique is sometimes called electron tomography. The examples presented here elucidate the dispersion of these nanoparticles in a natural rubber (NR) Matrix, which is a technologically very important biomass. It is made clear that such nanoparticles coalesce to form aggregates and they further coalesce to form agglomerates in the Rubbery Matrix. Once 3D-TEM images are established, one can evaluate all structural parameters, depending on the availability of software for each specific purpose. Here, the volume of each component in the composite, the size, the size distribution, the distance between neighboring aggregates, and the aspect ratio of the aggregates, for example, are evaluated as structural parameters. In the case of silica, 3D images of conventional silica and in situ formed silica are compared. The further coalescing of aggregates of both silica and carbon black particles results in the formation of agglomerates, the visualized images of which show that they form a kind of network structure in the rubber. In the case of carbon black, measurement of volume resistivity or electron conductivity reveals that percolation occurs near a volume fraction of 0.17 as a threshold value. Combining the resistivity results with a structural parameter, i.e., the nearest neighbor distance from 3D-TEM images, it is estimated that electrons hop over the rubber phase (which is an insulator), about 3 nm thick, between carbon black aggregates, thereby exhibiting electron conductivity. It is suggested from the results of this study that establishing the correlation between the 3D nanostructures as revealed by 3D-TEM and physical properties can play an important role in advancing the discipline of nanotechnology as an exact science, especially in the area of soft nanocomposites.
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nonuniformity in natural rubber as revealed by small angle neutron scattering small angle x ray scattering and atomic force microscopy
Biomacromolecules, 2007Co-Authors: Takeshi Karino, Yuko Ikeda, Shinzo Kohjiya, Yoritaka Yasuda, Mitsuhiro ShibayamaAbstract:The microscopic structures of natural rubber (NR) and deproteinized NR (DPNR) were investigated by means of small-angle neutron scattering (SANS), small-angle X-ray scattering (SAXS), and atomic force microscopy (AFM). They were compared to those of isoprene rubber (IR), which is a synthetic analogue of NR in terms of chemical structure without any non-rubber components like proteins. Comparisons of the structure and mechanical properties of NR, DPNR, and IR lead to the following conclusions. (i) The well-known facts, for example, the outstanding green strength of NR and strain-induced crystallization, are due not much to the presence of proteins but to other components such as the presence of phospholipids and/or the higher stereoregularity of NR. It also became clear the naturally residing proteins accelerate the upturn of stress at low strain. The protein phases work as cross-linking sites and reinforcing fillers in the Rubbery Matrix. (ii) The microscopic structures of NR were successfully reproduced ...
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visualisation of carbon black networks in Rubbery Matrix by skeletonisation of 3d tem image
Polymer, 2006Co-Authors: Shinzo Kohjiya, Atushi Katoh, Toshiya Suda, Junichi Shimanuki, Yuko IkedaAbstract:The first visualization of nanofiller networking due to association of carbon black in natural rubber is achieved by a transmission electron microscopy combined with computerised tomography (3D-TEM), and the resulted skeleton displays the characteristics of the filler network, which has long been assumed on the percolation behaviour in electron conductivity and on the mechanical behaviours of filled rubbers.
Pcmm Pieter Magusin - One of the best experts on this subject based on the ideXlab platform.
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rubber filler interactions and network structure in relation to stress strain behavior of vulcanized carbon black filled epdm
Macromolecules, 2011Co-Authors: V M Litvinov, R Ramona A Orza, Van Martin M Duin, Manfred Klüppel, Pcmm Pieter MagusinAbstract:Immobilization of EPDM chains on the surface of carbon black and network structure in the rubber Matrix of filled EPDM rubbers were studied by low-field proton NMR experiments. Advanced NMR experiments unambiguously show strong immobilization of EPDM chain fragments on the surface of carbon black. The thickness of the immobilized EPDM–carbon black interfacial layer is estimated to be ≥0.6 nm. The average number of monomer units per adsorption site is approximately nine, which suggests preferential chain adsorption at the crystal boundaries of carbon-black particles. The adsorbed chain fragments form physical (adsorption) junctions restricting chain mobility in the Rubbery Matrix outside of the interface. The cross-link density in filled EPDM is determined as a function of the filler type and its amount. The contribution of adsorption junctions to the total cross-link density is moderate as compared to the density of chemical cross-links and entanglement density. The mechanically effective network density ...
V M Litvinov - One of the best experts on this subject based on the ideXlab platform.
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rubber filler interactions and network structure in relation to stress strain behavior of vulcanized carbon black filled epdm
Macromolecules, 2011Co-Authors: V M Litvinov, R Ramona A Orza, Van Martin M Duin, Manfred Klüppel, Pcmm Pieter MagusinAbstract:Immobilization of EPDM chains on the surface of carbon black and network structure in the rubber Matrix of filled EPDM rubbers were studied by low-field proton NMR experiments. Advanced NMR experiments unambiguously show strong immobilization of EPDM chain fragments on the surface of carbon black. The thickness of the immobilized EPDM–carbon black interfacial layer is estimated to be ≥0.6 nm. The average number of monomer units per adsorption site is approximately nine, which suggests preferential chain adsorption at the crystal boundaries of carbon-black particles. The adsorbed chain fragments form physical (adsorption) junctions restricting chain mobility in the Rubbery Matrix outside of the interface. The cross-link density in filled EPDM is determined as a function of the filler type and its amount. The contribution of adsorption junctions to the total cross-link density is moderate as compared to the density of chemical cross-links and entanglement density. The mechanically effective network density ...
Zhigang Wang - One of the best experts on this subject based on the ideXlab platform.
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triblock copolymer elastomers with enhanced mechanical properties synthesized by raft polymerization and subsequent quaternization through incorporation of a comonomer with imidazole groups of about 2 0 mass percentage
Macromolecules, 2017Co-Authors: Feng Jiang, Chu Fang, Juan Zhang, Wentao Wang, Zhigang WangAbstract:ABA triblock copolymer elastomers (TBCPEs) were first synthesized via reversible addition–fragmentation chain transfer (RAFT) polymerization, for which poly(isobornyl acrylate) (PIBA) was chosen as the dispersed hard microdomains, whereas poly(n-butyl acrylate)-co-poly(1-vinylimidazole) (P(BA-co-VI)) was chosen as the Rubbery Matrix. Two much distinct glass transition temperatures were found, corresponding to the soft Matrix and hard microdomains, respectively. Although the mass percentages of the incorporated third comonomer, 1-vinylimidazole, were just about 2.0%, the imidazole groups on the TBCPE chains could be ionically cross-linked by 1,6-dibromohexane to bring these TBCPEs into much strong ones, half-cross-linked TBCPEs-HC and full-cross-linked TBCPEs-FC. It is interesting to demonstrate that the ultimate tensile strength for TBCPEs-FC could be increased up to 10 times that for TBCPEs, and the elastic recovery could also be improved to above 90%, while the elongation at break just showed modest dec...
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Triblock Copolymer Elastomers with Enhanced Mechanical Properties Synthesized by RAFT Polymerization and Subsequent Quaternization through Incorporation of a Comonomer with Imidazole Groups of about 2.0 Mass Percentage
2017Co-Authors: Feng Jiang, Chu Fang, Juan Zhang, Wentao Wang, Zhigang WangAbstract:ABA triblock copolymer elastomers (TBCPEs) were first synthesized via reversible addition–fragmentation chain transfer (RAFT) polymerization, for which poly(isobornyl acrylate) (PIBA) was chosen as the dispersed hard microdomains, whereas poly(n-butyl acrylate)-co-poly(1-vinylimidazole) (P(BA-co-VI)) was chosen as the Rubbery Matrix. Two much distinct glass transition temperatures were found, corresponding to the soft Matrix and hard microdomains, respectively. Although the mass percentages of the incorporated third comonomer, 1-vinylimidazole, were just about 2.0%, the imidazole groups on the TBCPE chains could be ionically cross-linked by 1,6-dibromohexane to bring these TBCPEs into much strong ones, half-cross-linked TBCPEs-HC and full-cross-linked TBCPEs-FC. It is interesting to demonstrate that the ultimate tensile strength for TBCPEs-FC could be increased up to 10 times that for TBCPEs, and the elastic recovery could also be improved to above 90%, while the elongation at break just showed modest decreases. Transmission electron microscope (TEM) and small-angle X-ray scattering (SAXS) measurements disclosed that TBCPEs, TBCPEs-HC, and TBCPEs-FC all had typical microphase-separated morphology, with the interdomain distance tunable by the molecular mass of TBCPEs. In-situ SAXS measurements revealed that the hard microdomains in TBCPEs-HC could be orientated along the tensile direction during stretching and be recovered to the original state after stress release
