The Experts below are selected from a list of 17964 Experts worldwide ranked by ideXlab platform
Lawrence W. Hrubesh - One of the best experts on this subject based on the ideXlab platform.
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Transparent ultralow-density Silica aerogels prepared by a two-step sol-gel process
Journal of Non-crystalline Solids, 2005Co-Authors: Thomas M. Tillotson, Lawrence W. HrubeshAbstract:Conventional Silica sol-gel chemistry is limited for the production of transparent ultralow-density aerogels because (1) gelation is either slow or unachievable, and (2) even when gelation is achieved, the large pore sizes result in loss of transparency for aerogels
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transparent ultralow density Silica aerogels prepared by a two step sol gel process
Journal of Non-crystalline Solids, 1992Co-Authors: Thomas M. Tillotson, Lawrence W. HrubeshAbstract:Conventional Silica sol-gel chemistry is limited for the production of transparent ultralow-density aerogels because (1) gelation is either slow or unachievable, and (2) even when gelation is achieved, the large pore sizes result in loss of transparency for aerogels <.020 g/cc. We have developed a two-step sol-gel process that circumvents the limitations of the Conventional process and allows the formation of ultralow-density gels in a matter of hours. we have found that the gel time is dependent on the catalyst concentration. After supercritical extraction, the aerogels are transparent, uncracked tiles with densities as low as .003 g/cc. 6 figs., 11 refs.
Thomas M. Tillotson - One of the best experts on this subject based on the ideXlab platform.
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Transparent ultralow-density Silica aerogels prepared by a two-step sol-gel process
Journal of Non-crystalline Solids, 2005Co-Authors: Thomas M. Tillotson, Lawrence W. HrubeshAbstract:Conventional Silica sol-gel chemistry is limited for the production of transparent ultralow-density aerogels because (1) gelation is either slow or unachievable, and (2) even when gelation is achieved, the large pore sizes result in loss of transparency for aerogels
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transparent ultralow density Silica aerogels prepared by a two step sol gel process
Journal of Non-crystalline Solids, 1992Co-Authors: Thomas M. Tillotson, Lawrence W. HrubeshAbstract:Conventional Silica sol-gel chemistry is limited for the production of transparent ultralow-density aerogels because (1) gelation is either slow or unachievable, and (2) even when gelation is achieved, the large pore sizes result in loss of transparency for aerogels <.020 g/cc. We have developed a two-step sol-gel process that circumvents the limitations of the Conventional process and allows the formation of ultralow-density gels in a matter of hours. we have found that the gel time is dependent on the catalyst concentration. After supercritical extraction, the aerogels are transparent, uncracked tiles with densities as low as .003 g/cc. 6 figs., 11 refs.
Kazuhide Nakajima - One of the best experts on this subject based on the ideXlab platform.
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Solid-Type Low-Latency Optical Fiber With Large Effective Area
Journal of Lightwave Technology, 2019Co-Authors: Yuto Sagae, Takashi Matsui, Kyozo Tsujikawa, Kazuhide NakajimaAbstract:Low-latency transmission is required by services emerging in today's optical communication networks, such as machine-to-machine communication. As transmission distances are now reaching several thousands of kilometers, the propagation latency in optical fiber cannot be ignored. In this study, we propose a solid-type low-latency optical fiber that has lower group delay than Conventional Silica core fibers. Numerical analyses and measurements show 0.3% lower group delay than a Conventional Silica core fiber, and its excellent optical properties include its large effective area, low nonlinearity and low loss comparable to that of Conventional single mode fiber.
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OFC - Multi-Functional Multi-Core Fiber with a Low-Latency Core and Conventional Silica Cores
Optical Fiber Communication Conference (OFC) 2019, 2019Co-Authors: Yuto Sagae, Takashi Matsui, Yoko Yamashita, Masaki Wada, Taiji Sakamoto, Kyozo Tsujikawa, Kazuhide NakajimaAbstract:We propose a novel multi-functional multi-core fiber (MF-MCF) composed of low-latency core and Conventional Silica-cores. MF-MCF can offer fast channel, and which is also expected to be management channels for realizing the advanced signal processing.
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multi functional multi core fiber with a low latency core and Conventional Silica cores
Optical Fiber Communication Conference, 2019Co-Authors: Yuto Sagae, Takashi Matsui, Yoko Yamashita, Masaki Wada, Taiji Sakamoto, Kyozo Tsujikawa, Kazuhide NakajimaAbstract:We propose a novel multi-functional multi-core fiber (MF-MCF) composed of low-latency core and Conventional Silica-cores. MF-MCF can offer fast channel, and which is also expected to be management channels for realizing the advanced signal processing.
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High tensile strength photonic crystal
2004Co-Authors: Jian Zhou, Katsusuke Tajima, Kenji Kurokawa, Kazuhide Nakajima, I. SaokawaAbstract:PCFs can have a higher tensile strength than Conventional Silica fibers because the holes prevent flaws from growing. A proper designed PCF shows a tensile strength of 7 kgf which is unobtainable with commercial SMF.
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High tensile strength photonic crystal fiber
2004Co-Authors: Jian Zhou, Katsusuke Tajima, Kenji Kurokawa, Kazuhide Nakajima, Izumi SankawaAbstract:PCFs can have a higher tensile strength than Conventional Silica fibers because the holes prevent flaws from growing. A proper designed PCF shows a tensile strength of 7kgf which is unobtainable with commercial SMF.
Yuko Ikeda - One of the best experts on this subject based on the ideXlab platform.
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Biaxial tensile behavior of rubber vulcanizates: I. Silica and gum stocks
Rubber Chemistry and Technology, 2004Co-Authors: Kanji Kajiwara, Yuko Ikeda, Yoshihiro Kameda, Hiroshi Urakawa, Takanobu Kawamura, Kenji Urayama, Shinzo KohjiyaAbstract:We have studied the strip biaxial tensile behavior of natural rubber vulcanizates filled with Silica by the Conventional milling method and by the in-situ Silica filling method. The rapid increase of both stresses along the stretching and the fixed axes after the initial stretching was observed on samples filled with a Conventional Silica by the milling method. Low strain dependence of stresses in the successive strain regions was followed by the rapid increase of the stresses at the higher deformation region. On the other hand, we did not observe such behavior for the samples filled with Silica generated in-situ in the rubber matrix before curing. The transmission electron microscopic measurements showed that a highly developed aggregated structure of Silica particles was suggested in the Conventional Silica filled samples and just a simple aggregation was suggested in the case of the in-situ Silica filled samples. The differences between samples reinforced with two different filling methods in low tensile region are mainly attributed to the aggregate structure of the Silica particles dispersed in the rubbery matrix. We estimated the functional form of the strain energy density function for the samples filled with Silica in intermediate and large deformation regions: W = C 10 (I 1 - 3) + C 01 (I 2 - 3) + C 20 (I 1 - 3) 2 The estimated W was found to reproduce the experimental stress-strain curves in intermediate and large deformation region. The relative contributions of three terms in the estimated W for the samples prepared by the in-situ method show the different dependence on the Silica content from those of the samples containing Silica mixed by the Conventional method.
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in situ formation of particulate Silica in natural rubber matrix by the sol gel reaction
Journal of Sol-Gel Science and Technology, 2003Co-Authors: Shinzo Kohjiya, Yuko IkedaAbstract:The sol-gel reaction of tetraethoxysilane was conducted in natural rubber (NR) matrix to obtain NR/in situ Silica mixtures. In other words, in situ filling of Silica onto NR was conducted. The mixtures were compounded with curing regents, and their viscosities were evaluated. The in situ Silica with a coupling agent afforded the lowest viscosity compared not only with a Conventional Silica (VN-3) but also with a carbon black (HAF). The curing behaviors were most favorable for in situ Silica compound. Physical properties of the vulcanizates were also evaluated, and again in situ Silica stock gave the best result.
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In Situ Filling of Silica onto “Green” Natural Rubber by the Sol—Gel Process
Rubber Chemistry and Technology, 2001Co-Authors: Shinzo Kohjiya, K. Murakami, S. Iio, T. Tanahashi, Yuko IkedaAbstract:Abstract The sol—gel reaction of tetraethoxysilane produced the fine and well-dispersed in situ Silica particles in the “green” natural rubber (NR) matrix before curing. This new method was developed for a NR/Silica composite material, and a good reinforcement effect of in situ Silica was observed on the NR vulcanizate. The method is expected to be an industrially practical technique. The in situ Silica did not much inhibit the accelerated sulfur curing. Thus, it is estimated that the concentration of silanol groups on the in situ Silica surface was smaller than those on the Conventional Silica surface. The Silica—Silica interaction of in situ Silica seems to be weaker to result in better dispersion in the rubber matrix compared with the Conventional Silica. Atomic force microscopy suggested that the wettability of NR onto in situ Silica was higher than that onto Conventional Silica. The hardness, modulus at 50% elongation and the storage modulus at room temperature of in situ Silica-filled NR vulcanizate...
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Reinforcement of natural rubber by Silica generated in situ
Proceedings of the Japan Academy. Ser. B: Physical and Biological Sciences, 2000Co-Authors: Shinzo Kohjiya, Yuko IkedaAbstract:New method to produce in situ Silica in natural rubber (NR) matrix was developed for a NR/Silica composite material, and the good reinforcement effect of the Silica was observed on the NR vulcanizate. The Silica was generated by the sol-gel reaction of tetraethoxysilane before crosslinking, which gave a homogeneous dispersion of in situ-generated Silica particles in the NR matrix. This method is expected to be an industrially practical technique. It is estimated that the concentration of silanol groups on the Silica surface were smaller than those on the Conventional Silica surface. Therefore, the Silica-Silica interaction of in situ Silica seems to be weaker than that of Silica-rubber to result in better dispersion compared with the Conventional Silica. The results suggest that NR which is a renewable resource and in situ Silica omposite has much potential as a“green”material and a useful system for studying the reinforcement mechanism of inorganic filler onto NR.
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Silica and silane coupling agent for in situ reinforcement of acrylonitrile-butadiene rubber
Rubber Chemistry and Technology, 1999Co-Authors: K. Murakami, Shinzo Kohjiya, S. Iio, H. Tanahashi, S. Osanai, M. Shigekuni, Yuko IkedaAbstract:Abstract In situ Silica reinforcement for the acrylonitrile-butadiene rubber (NBR) vulcanizates, which were premixed with a Conventional Silica (VN-3) and γ-mercaptopropyltrimethoxysilane (γ-MPS), was achieved by the sol-gel reaction of tetraethoxysilane (TEOS) using ethylenediamine. It was observed that the reinforcement efficiency tended to increase with the increase of mechanically premixed Conventional Silica. From the observations of transmission electron microscopy and scanning electron microscopy, the simultaneous use of VN-3 and γ-MPS was found to promote the formation of large Silica particles and clusters with a relatively good dispersion by the sol-gel reaction of TEOS in the NBR vulcanizate. The results of hysteresis measurements supported this promotion. It was considered to be due to the surface modification of VN-3 by the sol-gel reaction of TEOS and the presence of γ-MPS which worked as a dispersion agent for Silica particles. The relationship between the mechanical properties and the morp...
Shinzo Kohjiya - One of the best experts on this subject based on the ideXlab platform.
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Biaxial tensile behavior of rubber vulcanizates: I. Silica and gum stocks
Rubber Chemistry and Technology, 2004Co-Authors: Kanji Kajiwara, Yuko Ikeda, Yoshihiro Kameda, Hiroshi Urakawa, Takanobu Kawamura, Kenji Urayama, Shinzo KohjiyaAbstract:We have studied the strip biaxial tensile behavior of natural rubber vulcanizates filled with Silica by the Conventional milling method and by the in-situ Silica filling method. The rapid increase of both stresses along the stretching and the fixed axes after the initial stretching was observed on samples filled with a Conventional Silica by the milling method. Low strain dependence of stresses in the successive strain regions was followed by the rapid increase of the stresses at the higher deformation region. On the other hand, we did not observe such behavior for the samples filled with Silica generated in-situ in the rubber matrix before curing. The transmission electron microscopic measurements showed that a highly developed aggregated structure of Silica particles was suggested in the Conventional Silica filled samples and just a simple aggregation was suggested in the case of the in-situ Silica filled samples. The differences between samples reinforced with two different filling methods in low tensile region are mainly attributed to the aggregate structure of the Silica particles dispersed in the rubbery matrix. We estimated the functional form of the strain energy density function for the samples filled with Silica in intermediate and large deformation regions: W = C 10 (I 1 - 3) + C 01 (I 2 - 3) + C 20 (I 1 - 3) 2 The estimated W was found to reproduce the experimental stress-strain curves in intermediate and large deformation region. The relative contributions of three terms in the estimated W for the samples prepared by the in-situ method show the different dependence on the Silica content from those of the samples containing Silica mixed by the Conventional method.
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in situ formation of particulate Silica in natural rubber matrix by the sol gel reaction
Journal of Sol-Gel Science and Technology, 2003Co-Authors: Shinzo Kohjiya, Yuko IkedaAbstract:The sol-gel reaction of tetraethoxysilane was conducted in natural rubber (NR) matrix to obtain NR/in situ Silica mixtures. In other words, in situ filling of Silica onto NR was conducted. The mixtures were compounded with curing regents, and their viscosities were evaluated. The in situ Silica with a coupling agent afforded the lowest viscosity compared not only with a Conventional Silica (VN-3) but also with a carbon black (HAF). The curing behaviors were most favorable for in situ Silica compound. Physical properties of the vulcanizates were also evaluated, and again in situ Silica stock gave the best result.
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In Situ Filling of Silica onto “Green” Natural Rubber by the Sol—Gel Process
Rubber Chemistry and Technology, 2001Co-Authors: Shinzo Kohjiya, K. Murakami, S. Iio, T. Tanahashi, Yuko IkedaAbstract:Abstract The sol—gel reaction of tetraethoxysilane produced the fine and well-dispersed in situ Silica particles in the “green” natural rubber (NR) matrix before curing. This new method was developed for a NR/Silica composite material, and a good reinforcement effect of in situ Silica was observed on the NR vulcanizate. The method is expected to be an industrially practical technique. The in situ Silica did not much inhibit the accelerated sulfur curing. Thus, it is estimated that the concentration of silanol groups on the in situ Silica surface was smaller than those on the Conventional Silica surface. The Silica—Silica interaction of in situ Silica seems to be weaker to result in better dispersion in the rubber matrix compared with the Conventional Silica. Atomic force microscopy suggested that the wettability of NR onto in situ Silica was higher than that onto Conventional Silica. The hardness, modulus at 50% elongation and the storage modulus at room temperature of in situ Silica-filled NR vulcanizate...
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Reinforcement of natural rubber by Silica generated in situ
Proceedings of the Japan Academy. Ser. B: Physical and Biological Sciences, 2000Co-Authors: Shinzo Kohjiya, Yuko IkedaAbstract:New method to produce in situ Silica in natural rubber (NR) matrix was developed for a NR/Silica composite material, and the good reinforcement effect of the Silica was observed on the NR vulcanizate. The Silica was generated by the sol-gel reaction of tetraethoxysilane before crosslinking, which gave a homogeneous dispersion of in situ-generated Silica particles in the NR matrix. This method is expected to be an industrially practical technique. It is estimated that the concentration of silanol groups on the Silica surface were smaller than those on the Conventional Silica surface. Therefore, the Silica-Silica interaction of in situ Silica seems to be weaker than that of Silica-rubber to result in better dispersion compared with the Conventional Silica. The results suggest that NR which is a renewable resource and in situ Silica omposite has much potential as a“green”material and a useful system for studying the reinforcement mechanism of inorganic filler onto NR.
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Silica and silane coupling agent for in situ reinforcement of acrylonitrile-butadiene rubber
Rubber Chemistry and Technology, 1999Co-Authors: K. Murakami, Shinzo Kohjiya, S. Iio, H. Tanahashi, S. Osanai, M. Shigekuni, Yuko IkedaAbstract:Abstract In situ Silica reinforcement for the acrylonitrile-butadiene rubber (NBR) vulcanizates, which were premixed with a Conventional Silica (VN-3) and γ-mercaptopropyltrimethoxysilane (γ-MPS), was achieved by the sol-gel reaction of tetraethoxysilane (TEOS) using ethylenediamine. It was observed that the reinforcement efficiency tended to increase with the increase of mechanically premixed Conventional Silica. From the observations of transmission electron microscopy and scanning electron microscopy, the simultaneous use of VN-3 and γ-MPS was found to promote the formation of large Silica particles and clusters with a relatively good dispersion by the sol-gel reaction of TEOS in the NBR vulcanizate. The results of hysteresis measurements supported this promotion. It was considered to be due to the surface modification of VN-3 by the sol-gel reaction of TEOS and the presence of γ-MPS which worked as a dispersion agent for Silica particles. The relationship between the mechanical properties and the morp...