The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
John M. Torkelson - One of the best experts on this subject based on the ideXlab platform.
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importance of superior dispersion versus filler surface modification in producing robust polymer nanocomposites the example of polypropylene nanosilica hybrids
Polymer, 2015Co-Authors: Krishnan A. Iyer, John M. TorkelsonAbstract:Abstract With polymer nanocomposites, achieving highly effective dispersion of agglomerated nanofiller and major or optimal property enhancements remain challenges. A commonly posited solution is to improve the polymer-filler surface thermodynamic compatibility; this approach has led to significant improvements in some cases, but it has not provided a general solution. We address the question of whether achieving a metastable, well-Dispersed State is better than compatibilization in attaining the goal of major property enhancements. We use solid-State shear pulverization to produce well-Dispersed polypropylene (PP) nanocomposites with up to 8 or 9 wt% pristine nanosilica ( p -NS) or organically modified nanosilica ( m -NS). Microscopy shows that as-received, tens-of-micron-sized p -NS and m -NS agglomerates undergo very good dispersion, with ∼10–100 nm size-range nanofiller in hybrids. Rheology is consistent with very good dispersion, with only 92/8 wt% PP/ p -NS indicating incipient nanofiller network formation. The PP/ p -NS hybrids have superior Young's modulus and tensile strength. Relative to PP, modulus increases by 22% and 12% and tensile strength by 19% and 14% for 99/1 wt% PP/ p -NS and 99/1 wt% PP/ m -NS, respectively. The PP/ p -NS hybrids have the largest increases in modulus (46% at 8 wt% p -NS) and tensile strength (22% at 6 wt% p -NS). Upon melting and crystallization, both PP/ p -NS and PP/ m -NS result in PP β-crystal formation at 1 wt% nanosilica, with p -NS having a greater effect. The PP/ p -NS hybrid shows larger increases in thermal stability and nucleating efficiency for PP crystallization. Thus, with very good dispersion, unmodified nanofiller in a metastable Dispersed State can result in more robust nanocomposites than when modified nanofiller is used to compatibilize the polymer–nanofiller interface.
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Importance of superior dispersion versus filler surface modification in producing robust polymer nanocomposites: The example of polypropylene/nanosilica hybrids
Polymer, 2015Co-Authors: Krishnan A. Iyer, John M. TorkelsonAbstract:Abstract With polymer nanocomposites, achieving highly effective dispersion of agglomerated nanofiller and major or optimal property enhancements remain challenges. A commonly posited solution is to improve the polymer-filler surface thermodynamic compatibility; this approach has led to significant improvements in some cases, but it has not provided a general solution. We address the question of whether achieving a metastable, well-Dispersed State is better than compatibilization in attaining the goal of major property enhancements. We use solid-State shear pulverization to produce well-Dispersed polypropylene (PP) nanocomposites with up to 8 or 9 wt% pristine nanosilica ( p -NS) or organically modified nanosilica ( m -NS). Microscopy shows that as-received, tens-of-micron-sized p -NS and m -NS agglomerates undergo very good dispersion, with ∼10–100 nm size-range nanofiller in hybrids. Rheology is consistent with very good dispersion, with only 92/8 wt% PP/ p -NS indicating incipient nanofiller network formation. The PP/ p -NS hybrids have superior Young's modulus and tensile strength. Relative to PP, modulus increases by 22% and 12% and tensile strength by 19% and 14% for 99/1 wt% PP/ p -NS and 99/1 wt% PP/ m -NS, respectively. The PP/ p -NS hybrids have the largest increases in modulus (46% at 8 wt% p -NS) and tensile strength (22% at 6 wt% p -NS). Upon melting and crystallization, both PP/ p -NS and PP/ m -NS result in PP β-crystal formation at 1 wt% nanosilica, with p -NS having a greater effect. The PP/ p -NS hybrid shows larger increases in thermal stability and nucleating efficiency for PP crystallization. Thus, with very good dispersion, unmodified nanofiller in a metastable Dispersed State can result in more robust nanocomposites than when modified nanofiller is used to compatibilize the polymer–nanofiller interface.
Krishnan A. Iyer - One of the best experts on this subject based on the ideXlab platform.
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importance of superior dispersion versus filler surface modification in producing robust polymer nanocomposites the example of polypropylene nanosilica hybrids
Polymer, 2015Co-Authors: Krishnan A. Iyer, John M. TorkelsonAbstract:Abstract With polymer nanocomposites, achieving highly effective dispersion of agglomerated nanofiller and major or optimal property enhancements remain challenges. A commonly posited solution is to improve the polymer-filler surface thermodynamic compatibility; this approach has led to significant improvements in some cases, but it has not provided a general solution. We address the question of whether achieving a metastable, well-Dispersed State is better than compatibilization in attaining the goal of major property enhancements. We use solid-State shear pulverization to produce well-Dispersed polypropylene (PP) nanocomposites with up to 8 or 9 wt% pristine nanosilica ( p -NS) or organically modified nanosilica ( m -NS). Microscopy shows that as-received, tens-of-micron-sized p -NS and m -NS agglomerates undergo very good dispersion, with ∼10–100 nm size-range nanofiller in hybrids. Rheology is consistent with very good dispersion, with only 92/8 wt% PP/ p -NS indicating incipient nanofiller network formation. The PP/ p -NS hybrids have superior Young's modulus and tensile strength. Relative to PP, modulus increases by 22% and 12% and tensile strength by 19% and 14% for 99/1 wt% PP/ p -NS and 99/1 wt% PP/ m -NS, respectively. The PP/ p -NS hybrids have the largest increases in modulus (46% at 8 wt% p -NS) and tensile strength (22% at 6 wt% p -NS). Upon melting and crystallization, both PP/ p -NS and PP/ m -NS result in PP β-crystal formation at 1 wt% nanosilica, with p -NS having a greater effect. The PP/ p -NS hybrid shows larger increases in thermal stability and nucleating efficiency for PP crystallization. Thus, with very good dispersion, unmodified nanofiller in a metastable Dispersed State can result in more robust nanocomposites than when modified nanofiller is used to compatibilize the polymer–nanofiller interface.
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Importance of superior dispersion versus filler surface modification in producing robust polymer nanocomposites: The example of polypropylene/nanosilica hybrids
Polymer, 2015Co-Authors: Krishnan A. Iyer, John M. TorkelsonAbstract:Abstract With polymer nanocomposites, achieving highly effective dispersion of agglomerated nanofiller and major or optimal property enhancements remain challenges. A commonly posited solution is to improve the polymer-filler surface thermodynamic compatibility; this approach has led to significant improvements in some cases, but it has not provided a general solution. We address the question of whether achieving a metastable, well-Dispersed State is better than compatibilization in attaining the goal of major property enhancements. We use solid-State shear pulverization to produce well-Dispersed polypropylene (PP) nanocomposites with up to 8 or 9 wt% pristine nanosilica ( p -NS) or organically modified nanosilica ( m -NS). Microscopy shows that as-received, tens-of-micron-sized p -NS and m -NS agglomerates undergo very good dispersion, with ∼10–100 nm size-range nanofiller in hybrids. Rheology is consistent with very good dispersion, with only 92/8 wt% PP/ p -NS indicating incipient nanofiller network formation. The PP/ p -NS hybrids have superior Young's modulus and tensile strength. Relative to PP, modulus increases by 22% and 12% and tensile strength by 19% and 14% for 99/1 wt% PP/ p -NS and 99/1 wt% PP/ m -NS, respectively. The PP/ p -NS hybrids have the largest increases in modulus (46% at 8 wt% p -NS) and tensile strength (22% at 6 wt% p -NS). Upon melting and crystallization, both PP/ p -NS and PP/ m -NS result in PP β-crystal formation at 1 wt% nanosilica, with p -NS having a greater effect. The PP/ p -NS hybrid shows larger increases in thermal stability and nucleating efficiency for PP crystallization. Thus, with very good dispersion, unmodified nanofiller in a metastable Dispersed State can result in more robust nanocomposites than when modified nanofiller is used to compatibilize the polymer–nanofiller interface.
Mamoru Nomura - One of the best experts on this subject based on the ideXlab platform.
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Film‐formation property of vinylidene chloride‐methyl methacrylate copolymer latex. I. Effect of emulsion‐polymerization process
Journal of Polymer Science Part B: Polymer Physics, 2002Co-Authors: Hideki Sakai, Takahiko Kodani, Atsuko Takayama, Mamoru NomuraAbstract:Changes in minimum film-formation temperature (MFFT) during storage of latexes prepared from 91:9 wt % vinylidene chloride (VDC)-methyl methacrylate (MMA) monomer mixture by seeded batch and seeded semicontinuous emulsion polymerization were investigated, with attention centered on polymer-crystallization behavior during storage in the Dispersed State. MFFT of latex prepared by the seeded batch process rose to 47 °C, whereas that of latex prepared by seeded semicontinuous process remained below 14 °C with storage at 20 °C for 12 weeks. Infrared absorption of latexes in the Dispersed State and wide-angle X-ray diffraction of powder polymers obtained by lyophilization of fresh and stored latexes both indicated a much greater increase in polymer crystallinity during storage with latex prepared by the seeded batch process than with that prepared by the seeded semicontinuous process. Analysis of the copolymer composition drift calculated from reactivity ratios and 1H NMR analysis indicated a wider sequence distribution and longer VDC sequences in polymer prepared by the seeded batch process than in polymer prepared by the seeded semicontinuous process. This explained the higher rate of crystallization during storage with latex prepared by the seeded batch process than with that prepared by the seeded semicontinuous process. Rising crystallinity during storage in the Dispersed State is believed to have caused the MFFT rise. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 939–947, 2002
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Effect of storage on film-formation property of vinylidene chloride-acrylonitrile-methyl acrylate terpolymer Latex
Journal of Applied Polymer Science, 1998Co-Authors: Takahiko Kodani, Hideki Sakai, Atsuko Takayama, Mamoru NomuraAbstract:Latex prepared from 91: 5: 4 wt % vinylidene chloride-acrylonitrile-methyl acrylate monomer mixture by seeded semicontinuous emulsion polymerization was investigated for a change in minimum film-formation temperature (MFFT) during storage, with focus placed on polymer crystallinity in the Dispersed State. MFFT rose from 20°C to 32°C, with storage at 20°C for 49 weeks. Infrared absorption of fresh and stored latexes in the Dispersed State indicated an increase in absorbance at 1048 cm -1 , which is characteristic of a crystalline vinylidene chloride polymer, that correlated with the MFFT rise with storage. This suggested that the MFFT rise with storage was caused by increasing crystallinity of the polymer in the Dispersed State. X-ray wide-angle diffraction and infrared absorption of powder polymers obtained by lyophilization of fresh and stored latexes also indicated increasing crystallinity with latex storage. Oxygen gas permeabilities of films coated with fresh and stored latexes were measured. Latex stored for long periods exhibited poor barrier property, indicating that such latex is unsuitable as an industrial barrier coating material for films and papers.
Hiroaki Tada - One of the best experts on this subject based on the ideXlab platform.
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Ultrafast photosynthetic reduction of elemental sulfur by Au nanoparticle-loaded TiO2.
The journal of physical chemistry. B, 2006Co-Authors: Tomokazu Kiyonaga, Tomohiro Mitsui, Motofumi Torikoshi, Manabu Takekawa, Tetsuro Soejima, Hiroaki TadaAbstract:Nanometer-sized gold particles with varying mean size from 3.2 to 12.2 nm were loaded on the surfaces of TiO2 particles in a highly Dispersed State with the loading amount maintained constant (0.46...
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Drastic enhancement of TiO2-photocatalyzed reduction of nitrobenzene by loading Ag clusters.
Langmuir : the ACS journal of surfaces and colloids, 2004Co-Authors: Hiroaki Tada, Tetsuji Ishida, And Ayako Takao, Seishiro ItoAbstract:Ag clusters (mean diameter = 1.5 nm, standard deviation = 0.37 nm) were photodeposited on TiO(2) particles in a highly Dispersed State. The loading of a small amount of the Ag clusters (0.24 wt %) dramatically enhanced both the activity for the TiO(2) photocatalytic reduction of nitrobenzene and the product selectivity of aniline. The essential action mechanism of the Ag clusters is discussed.
Hideki Sakai - One of the best experts on this subject based on the ideXlab platform.
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Film‐formation property of vinylidene chloride‐methyl methacrylate copolymer latex. I. Effect of emulsion‐polymerization process
Journal of Polymer Science Part B: Polymer Physics, 2002Co-Authors: Hideki Sakai, Takahiko Kodani, Atsuko Takayama, Mamoru NomuraAbstract:Changes in minimum film-formation temperature (MFFT) during storage of latexes prepared from 91:9 wt % vinylidene chloride (VDC)-methyl methacrylate (MMA) monomer mixture by seeded batch and seeded semicontinuous emulsion polymerization were investigated, with attention centered on polymer-crystallization behavior during storage in the Dispersed State. MFFT of latex prepared by the seeded batch process rose to 47 °C, whereas that of latex prepared by seeded semicontinuous process remained below 14 °C with storage at 20 °C for 12 weeks. Infrared absorption of latexes in the Dispersed State and wide-angle X-ray diffraction of powder polymers obtained by lyophilization of fresh and stored latexes both indicated a much greater increase in polymer crystallinity during storage with latex prepared by the seeded batch process than with that prepared by the seeded semicontinuous process. Analysis of the copolymer composition drift calculated from reactivity ratios and 1H NMR analysis indicated a wider sequence distribution and longer VDC sequences in polymer prepared by the seeded batch process than in polymer prepared by the seeded semicontinuous process. This explained the higher rate of crystallization during storage with latex prepared by the seeded batch process than with that prepared by the seeded semicontinuous process. Rising crystallinity during storage in the Dispersed State is believed to have caused the MFFT rise. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 939–947, 2002
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Effect of storage on film-formation property of vinylidene chloride-acrylonitrile-methyl acrylate terpolymer Latex
Journal of Applied Polymer Science, 1998Co-Authors: Takahiko Kodani, Hideki Sakai, Atsuko Takayama, Mamoru NomuraAbstract:Latex prepared from 91: 5: 4 wt % vinylidene chloride-acrylonitrile-methyl acrylate monomer mixture by seeded semicontinuous emulsion polymerization was investigated for a change in minimum film-formation temperature (MFFT) during storage, with focus placed on polymer crystallinity in the Dispersed State. MFFT rose from 20°C to 32°C, with storage at 20°C for 49 weeks. Infrared absorption of fresh and stored latexes in the Dispersed State indicated an increase in absorbance at 1048 cm -1 , which is characteristic of a crystalline vinylidene chloride polymer, that correlated with the MFFT rise with storage. This suggested that the MFFT rise with storage was caused by increasing crystallinity of the polymer in the Dispersed State. X-ray wide-angle diffraction and infrared absorption of powder polymers obtained by lyophilization of fresh and stored latexes also indicated increasing crystallinity with latex storage. Oxygen gas permeabilities of films coated with fresh and stored latexes were measured. Latex stored for long periods exhibited poor barrier property, indicating that such latex is unsuitable as an industrial barrier coating material for films and papers.