The Experts below are selected from a list of 9738 Experts worldwide ranked by ideXlab platform
Michal Kruk - One of the best experts on this subject based on the ideXlab platform.
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Pluronic-P123-Templated Synthesis of Silica with Cubic Ia3d Structure in the Presence of Micelle Swelling Agent.
Langmuir : the ACS journal of surfaces and colloids, 2015Co-Authors: Michal KrukAbstract:The syntheses of silicas with highly ordered cubic Ia3d structure templated by Pluronic P123 (EO20PO70EO20) block copolymer surfactant and sodium dodecyl sulfate (SDS) additive in the presence of Swelling Agents are demonstrated. It was found that the cubic Ia3d silica forms at 25 °C when a moderate amount of a Swelling Agent, such as 1,3,5-triisopropylbenzene (TIPB), 1,4-diisopropylbenzene (DIPB), or 1,3,5-triethylbenzene (TEB), is added. However, 1,3,5-trimethylbenzene was not found suitable, suggesting that the success of the synthesis requires a careful selection of a Swelling Agent. An increase in the relative amount of the Swelling Agent in a limited range tends to cause an increase in the unit-cell size, while a further unit cell parameter increase can be accomplished with TIPB through a concomitant decrease in the synthesis temperature and increase in the relative amount of the Swelling Agent. Many of the cubic Ia3d products, including those with the largest attained unit-cell sizes, were highly o...
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Versatile Surfactant/Swelling-Agent Template for Synthesis of Large-Pore Ordered Mesoporous Silicas and Related Hollow Nanoparticles
Chemistry of Materials, 2015Co-Authors: Liang Huang, Michal KrukAbstract:A surfactant/Swelling-Agent pair suitable for templating a variety of well-defined large-pore nanoporous silicas was identified. The pair includes a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide), PEO-PPO-PEO, block copolymer surfactant (Pluronic F127, EO106PO70EO106) with a large fraction of long hydrophilic PEO blocks and a Swelling Agent (toluene) that strongly solubilizes in micelles of the PEO-PPO-PEO surfactant family. Such a combination affords micellar templates for both spherical and cylindrical mesopores with potential to hinder cross-linking of micelle-templated nanostructures due to stabilization of nanoparticles by long PEO chains. Under low-temperature conditions (11–12 °C), the Pluronic F127/toluene pair affords ultralarge-pore FDU-12 (ULP-FDU-12) silica with face-centered cubic structure of spherical mesopores and related hollow nanospheres, as well as large-pore SBA-15 (LP-SBA-15) with two-dimensional hexagonal structure of cylindrical mesopores and related silica nanotub...
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versatile surfactant Swelling Agent template for synthesis of large pore ordered mesoporous silicas and related hollow nanoparticles
Chemistry of Materials, 2015Co-Authors: Liang Huang, Michal KrukAbstract:A surfactant/Swelling-Agent pair suitable for templating a variety of well-defined large-pore nanoporous silicas was identified. The pair includes a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide), PEO-PPO-PEO, block copolymer surfactant (Pluronic F127, EO106PO70EO106) with a large fraction of long hydrophilic PEO blocks and a Swelling Agent (toluene) that strongly solubilizes in micelles of the PEO-PPO-PEO surfactant family. Such a combination affords micellar templates for both spherical and cylindrical mesopores with potential to hinder cross-linking of micelle-templated nanostructures due to stabilization of nanoparticles by long PEO chains. Under low-temperature conditions (11–12 °C), the Pluronic F127/toluene pair affords ultralarge-pore FDU-12 (ULP-FDU-12) silica with face-centered cubic structure of spherical mesopores and related hollow nanospheres, as well as large-pore SBA-15 (LP-SBA-15) with two-dimensional hexagonal structure of cylindrical mesopores and related silica nanotub...
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Access to Ultralarge-Pore Ordered Mesoporous Materials through Selection of Surfactant/Swelling-Agent Micellar Templates
Accounts of chemical research, 2012Co-Authors: Michal KrukAbstract:The surfactant-micelle-templating method has revolutionized the synthesis of high-surface-area materials with mesopores (diameter 2–50 nm) that have well-defined shapes and sizes. One of the major benefits of this method is the ability to tailor the pore size by manipulating the size of the templating micelles. The uniform pores typically form ordered arrays.Although the choice of surfactant can tune the size of the micelles, it is more convenient to use a single surfactant and tailor the micelle size by adding a Swelling Agent. Unfortunately, the Swelling Agent tends to induce disorder or heterogeneity in the resulting structures, which can make this approach difficult to implement. We hypothesized that the Swelling Agents that are moderately solubilized within the micelles of a particular surfactant could generate well-defined micelle-templated structures with significantly enlarged pores.Using this idea, we could judiciously select candidate Swelling Agents from families of compounds whose extent of so...
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access to ultralarge pore ordered mesoporous materials through selection of surfactant Swelling Agent micellar templates
Accounts of Chemical Research, 2012Co-Authors: Michal KrukAbstract:The surfactant-micelle-templating method has revolutionized the synthesis of high-surface-area materials with mesopores (diameter 2–50 nm) that have well-defined shapes and sizes. One of the major benefits of this method is the ability to tailor the pore size by manipulating the size of the templating micelles. The uniform pores typically form ordered arrays.Although the choice of surfactant can tune the size of the micelles, it is more convenient to use a single surfactant and tailor the micelle size by adding a Swelling Agent. Unfortunately, the Swelling Agent tends to induce disorder or heterogeneity in the resulting structures, which can make this approach difficult to implement. We hypothesized that the Swelling Agents that are moderately solubilized within the micelles of a particular surfactant could generate well-defined micelle-templated structures with significantly enlarged pores.Using this idea, we could judiciously select candidate Swelling Agents from families of compounds whose extent of so...
Buxing Han - One of the best experts on this subject based on the ideXlab platform.
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Modification of isotactic polypropylene films by grafting methyl acrylate using supercritical CO2 as a Swelling Agent
The Journal of Supercritical Fluids, 2004Co-Authors: Zexuan Dong, Buxing Han, Zhimin Liu, Xiaowei Pei, Lili Liu, Guanying YangAbstract:Abstract Modification of isotactic polypropylene (iPP) films was carried out by grafting methyl acrylate (MA) onto its backbone using supercritical (SC) CO 2 as a solvent and Swelling Agent at 308.15 K, followed by thermal polymerization of MA within supercritical CO 2 (SC CO 2 )-swollen iPP film after releasing CO 2 , resulting in iPP-g-PMA composites. The grafting level can be controlled by the soaking time, pressure, concentrations of monomer and initiator in the fluid phase, reaction temperature and reaction time. The morphology and structure of the products were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and wide angle X-ray diffraction (WAXD).
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Supercritical CO2-assisted synthesis of poly(acrylic acid)/nylon6 and polystyrene/nylon6 blends
Polymer, 2003Co-Authors: Yuning Chang, Buxing Han, Yukun LiuAbstract:Abstract Poly(acrylic acid)/nylon6 and polystyrene/nylon6 blends were prepared using supercritical CO2 as substrate-Swelling Agent and monomer/initiator carrier. Both supercritical CO2/nylon6 binary system and SC CO2/monomer/nylon6 ternary system were studied. Virgin nylon6 and synthesized blends were characterized through differential scanning calorimetry, infrared spectroscopy, and polarizing microscopy. Supercritical CO2-induced crystallization was found in modified nylon6.
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Modification of isotactic polypropylene film by grafting of acrylic acid using supercritical CO2 as a Swelling Agent
Journal of Materials Chemistry, 2002Co-Authors: Zexuan Dong, Buxing Han, Zhimin Liu, Tao Jiang, Guanying YangAbstract:Modification of isotactic polypropylene (iPP) film was carried out by grafting of acrylic acid (AA) onto its backbone using supercritical (SC) CO2 as a solvent and Swelling Agent. The iPP film was impregnated with the monomer AA and benzoyl peroxide initiator using SC CO2 at 308.15 K, followed by thermal polymerization of AA within SC CO2-swollen iPP film, resulting in iPP-g-PAA composites. The degree of grafting can be controlled by variation of the soaking time, pressure, concentrations of monomer and initiator in the fluid phase, reaction temperature, and time. The morphology and structure of the products were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry, and wide angle X-ray diffraction.
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preparation of nanometer dispersed polypropylene polystyrene interpenetrating network using supercritical co2 as a Swelling Agent
Polymer, 2002Co-Authors: Zhimin Liu, Buxing Han, Liping Song, Guanying Yang, Tao JiangAbstract:Abstract Nanometer dispersed polypropylene/polystyrene (PP/PS) interpenetrating networks (IPNs) have been prepared by the radical polymerization and crosslinking of styrene (St) within supercritical (SC) CO 2 –swollen PP substrates. In this method, monomer St, crosslinking Agent divinyl benzene (DVB), and the initiator benzoyl peroxide were first impregnated into PP matrix using SC CO 2 as a solvent and Swelling Agent at 35.0 °C, and then the polymerization and crosslinking were carried out at 120 °C. The composition of the IPNs can be controlled by SC CO 2 pressure, concentrations of St and DVB in the fluid phase. Transmission electron microscopy shows that the PS is homogeneously dispersed in the IPNs and its phase size is in the range of 20–30 nm. The impact strength, tensile strength, and elongation-at-break of the PP/PS IPNs increase with increasing PS percentage in the IPNs.
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synthesis of composites of silicon rubber and polystyrene using supercritical co2 as a Swelling Agent
Journal of Materials Chemistry, 2002Co-Authors: Zhimin Liu, Buxing Han, Xinhua Dai, Guanying Yang, Zexuan Dong, Jiaqiu Wang, Xiaoli ZhangAbstract:The heterogeneous free-radical polymerization of styrene within supercritical carbon dioxide swollen silicon rubber film has been conducted to prepare the silicon rubber/polystyrene (SR/PS) polymer blends. The PS content in the blends can be controlled by adjusting the soaking time and the concentration of styrene in the supercritical fluid. Scanning electron microscopy (SEM) indicates that the PS phase is uniformly distributed in the blends and the phase size is very small (100 nm to 300 nm), although the two polymers are very different and incompatible. The mechanical properties of the blends and the average molecular weight of the PS polymerized in the matrix were also measured. The results indicate that the average molecular weight of the PS in the blend depends on the PS content or its phase size. The tensile strength of the blends is higher than that of original SR substrate, and there is a maximum in tensile strength vs. PS content. The Young's modulus of the blends increases monotonously with PS content in the blends.
Thomas Bechtold - One of the best experts on this subject based on the ideXlab platform.
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Aqueous thiocyanate-urea solution as a powerful non-alkaline Swelling Agent for cellulose fibres.
Carbohydrate polymers, 2014Co-Authors: Amalid Mahmud-ali, Thomas BechtoldAbstract:Abstract For many applications cellulose fibres are treated with concentrated solutions of Swelling Agents to increase reactivity and to achieve reorganisation of fibre structure. Representative examples are caustic soda, potassium hydroxide solution or liquid ammonia. These highly concentrated media bear considerable safety hazards during the technical handling thus alternative Swelling Agents are of interest. The thiocyanate–urea system investigated in this work offers high Swelling potential for regenerated cellulose fibres. Experiments with different cations of M + in M + SCN − demonstrate the significant influence of the cation on the degree of fibre Swelling. In concentrated NaSCN/urea solutions, at 80 °C, lyocell fibres expand the diameter from 12–14 to 100 μm. The treatment in the Swelling Agent also led to a significant increase in the water retention value which was accompanied by a strength loss of 20–40% of the initial value. FTIR analysis of treated fibres did not indicate substantial changes in structure of the cellulose polymer. Limited weight loss of up to 20% was observed despite the high expansion of the fibre.
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Aqueous thiocyanate–urea solution as a powerful non-alkaline Swelling Agent for cellulose fibres
Carbohydrate Polymers, 2014Co-Authors: Amalid Mahmud-ali, Thomas BechtoldAbstract:Abstract For many applications cellulose fibres are treated with concentrated solutions of Swelling Agents to increase reactivity and to achieve reorganisation of fibre structure. Representative examples are caustic soda, potassium hydroxide solution or liquid ammonia. These highly concentrated media bear considerable safety hazards during the technical handling thus alternative Swelling Agents are of interest. The thiocyanate–urea system investigated in this work offers high Swelling potential for regenerated cellulose fibres. Experiments with different cations of M + in M + SCN − demonstrate the significant influence of the cation on the degree of fibre Swelling. In concentrated NaSCN/urea solutions, at 80 °C, lyocell fibres expand the diameter from 12–14 to 100 μm. The treatment in the Swelling Agent also led to a significant increase in the water retention value which was accompanied by a strength loss of 20–40% of the initial value. FTIR analysis of treated fibres did not indicate substantial changes in structure of the cellulose polymer. Limited weight loss of up to 20% was observed despite the high expansion of the fibre.
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Fibrillation Tendency of Cellulosic Fibers. Part 1: Effects of Swelling
Cellulose, 2005Co-Authors: Wangsun Zhang, Satoko Okubayashi, Thomas BechtoldAbstract:The fibrillation tendencies of various cellulosic fibers in aqueous solution containing alkali metal hydroxide and ethanol were evaluated with two specific parameters: the critical point of fibrillation (CPF_conc.), that is a concentration of Swelling Agent where the fibrillation begins, and the ratio of initial increase in fibril number to increase in concentration of Swelling Agent ( I _ i ). The CPF_conc. and the I _ i are defined as fibrillation stability and fibrillation sensitivity to Swelling Agent, respectively. Lyocell fiber (CLY1) has the smallest CPF_conc. and the largest I _ i , representing the lowest fibrillation stability and the highest fibrillation sensitivity, leading to the highest fibrillation tendency in CLY1 among the fibers tested. Although crosslinking improved fibrillation stability in lyocell as compared to modal, the fibrillation stability remained higher owing to the high water capacity and the high affinity for alkali. In alkali solution at the same concentration CLY1 fibrillation increased in the order of LiOH > NaOH > KOH. However, the plot of fibril number against solvent retention value of CLY1 in different alkaline solutions gives a slope of 110 count · g/cm^3 regardless of alkali type, the critical degree of Swelling for CLY1 with no fibrillation was 0.62 cm^3/g in alkali solutions and 0.45 cm^3/g in ethanol/water mixture.
Zhimin Liu - One of the best experts on this subject based on the ideXlab platform.
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Modification of isotactic polypropylene films by grafting methyl acrylate using supercritical CO2 as a Swelling Agent
The Journal of Supercritical Fluids, 2004Co-Authors: Zexuan Dong, Buxing Han, Zhimin Liu, Xiaowei Pei, Lili Liu, Guanying YangAbstract:Abstract Modification of isotactic polypropylene (iPP) films was carried out by grafting methyl acrylate (MA) onto its backbone using supercritical (SC) CO 2 as a solvent and Swelling Agent at 308.15 K, followed by thermal polymerization of MA within supercritical CO 2 (SC CO 2 )-swollen iPP film after releasing CO 2 , resulting in iPP-g-PMA composites. The grafting level can be controlled by the soaking time, pressure, concentrations of monomer and initiator in the fluid phase, reaction temperature and reaction time. The morphology and structure of the products were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and wide angle X-ray diffraction (WAXD).
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Modification of isotactic polypropylene film by grafting of acrylic acid using supercritical CO2 as a Swelling Agent
Journal of Materials Chemistry, 2002Co-Authors: Zexuan Dong, Buxing Han, Zhimin Liu, Tao Jiang, Guanying YangAbstract:Modification of isotactic polypropylene (iPP) film was carried out by grafting of acrylic acid (AA) onto its backbone using supercritical (SC) CO2 as a solvent and Swelling Agent. The iPP film was impregnated with the monomer AA and benzoyl peroxide initiator using SC CO2 at 308.15 K, followed by thermal polymerization of AA within SC CO2-swollen iPP film, resulting in iPP-g-PAA composites. The degree of grafting can be controlled by variation of the soaking time, pressure, concentrations of monomer and initiator in the fluid phase, reaction temperature, and time. The morphology and structure of the products were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry, and wide angle X-ray diffraction.
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preparation of nanometer dispersed polypropylene polystyrene interpenetrating network using supercritical co2 as a Swelling Agent
Polymer, 2002Co-Authors: Zhimin Liu, Buxing Han, Liping Song, Guanying Yang, Tao JiangAbstract:Abstract Nanometer dispersed polypropylene/polystyrene (PP/PS) interpenetrating networks (IPNs) have been prepared by the radical polymerization and crosslinking of styrene (St) within supercritical (SC) CO 2 –swollen PP substrates. In this method, monomer St, crosslinking Agent divinyl benzene (DVB), and the initiator benzoyl peroxide were first impregnated into PP matrix using SC CO 2 as a solvent and Swelling Agent at 35.0 °C, and then the polymerization and crosslinking were carried out at 120 °C. The composition of the IPNs can be controlled by SC CO 2 pressure, concentrations of St and DVB in the fluid phase. Transmission electron microscopy shows that the PS is homogeneously dispersed in the IPNs and its phase size is in the range of 20–30 nm. The impact strength, tensile strength, and elongation-at-break of the PP/PS IPNs increase with increasing PS percentage in the IPNs.
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synthesis of composites of silicon rubber and polystyrene using supercritical co2 as a Swelling Agent
Journal of Materials Chemistry, 2002Co-Authors: Zhimin Liu, Buxing Han, Xinhua Dai, Guanying Yang, Zexuan Dong, Jiaqiu Wang, Xiaoli ZhangAbstract:The heterogeneous free-radical polymerization of styrene within supercritical carbon dioxide swollen silicon rubber film has been conducted to prepare the silicon rubber/polystyrene (SR/PS) polymer blends. The PS content in the blends can be controlled by adjusting the soaking time and the concentration of styrene in the supercritical fluid. Scanning electron microscopy (SEM) indicates that the PS phase is uniformly distributed in the blends and the phase size is very small (100 nm to 300 nm), although the two polymers are very different and incompatible. The mechanical properties of the blends and the average molecular weight of the PS polymerized in the matrix were also measured. The results indicate that the average molecular weight of the PS in the blend depends on the PS content or its phase size. The tensile strength of the blends is higher than that of original SR substrate, and there is a maximum in tensile strength vs. PS content. The Young's modulus of the blends increases monotonously with PS content in the blends.
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Preparation of Poly(vinyl chloride)/polystyrene miscible blends using supercritical CO2 as a Swelling Agent
Macromolecular Rapid Communications, 2002Co-Authors: Xinhua Dai, Buxing Han, Zhimin Liu, Guangying Yang, Xiaoli Zhang, Minglong YaoAbstract:Poly(vinyl chloride)/polystyrene (PVC/ PS) blends were prepared by using supercritical CO 2 as a Swelling Agent, and by thermally polymerizing styrene within the PVC matrix. It could be demonstrated by means of scarming electronic microscopy that PS was dispersed uniformly in the PVC matrix with very fine phase size, According to differential scanning calorimetry measurements and dynamic mechanical analysis, each blend had one single glass transition temperature, which indicated that compatible blends were obtained.
Guanying Yang - One of the best experts on this subject based on the ideXlab platform.
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Modification of isotactic polypropylene films by grafting methyl acrylate using supercritical CO2 as a Swelling Agent
The Journal of Supercritical Fluids, 2004Co-Authors: Zexuan Dong, Buxing Han, Zhimin Liu, Xiaowei Pei, Lili Liu, Guanying YangAbstract:Abstract Modification of isotactic polypropylene (iPP) films was carried out by grafting methyl acrylate (MA) onto its backbone using supercritical (SC) CO 2 as a solvent and Swelling Agent at 308.15 K, followed by thermal polymerization of MA within supercritical CO 2 (SC CO 2 )-swollen iPP film after releasing CO 2 , resulting in iPP-g-PMA composites. The grafting level can be controlled by the soaking time, pressure, concentrations of monomer and initiator in the fluid phase, reaction temperature and reaction time. The morphology and structure of the products were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and wide angle X-ray diffraction (WAXD).
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Modification of isotactic polypropylene film by grafting of acrylic acid using supercritical CO2 as a Swelling Agent
Journal of Materials Chemistry, 2002Co-Authors: Zexuan Dong, Buxing Han, Zhimin Liu, Tao Jiang, Guanying YangAbstract:Modification of isotactic polypropylene (iPP) film was carried out by grafting of acrylic acid (AA) onto its backbone using supercritical (SC) CO2 as a solvent and Swelling Agent. The iPP film was impregnated with the monomer AA and benzoyl peroxide initiator using SC CO2 at 308.15 K, followed by thermal polymerization of AA within SC CO2-swollen iPP film, resulting in iPP-g-PAA composites. The degree of grafting can be controlled by variation of the soaking time, pressure, concentrations of monomer and initiator in the fluid phase, reaction temperature, and time. The morphology and structure of the products were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry, and wide angle X-ray diffraction.
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preparation of nanometer dispersed polypropylene polystyrene interpenetrating network using supercritical co2 as a Swelling Agent
Polymer, 2002Co-Authors: Zhimin Liu, Buxing Han, Liping Song, Guanying Yang, Tao JiangAbstract:Abstract Nanometer dispersed polypropylene/polystyrene (PP/PS) interpenetrating networks (IPNs) have been prepared by the radical polymerization and crosslinking of styrene (St) within supercritical (SC) CO 2 –swollen PP substrates. In this method, monomer St, crosslinking Agent divinyl benzene (DVB), and the initiator benzoyl peroxide were first impregnated into PP matrix using SC CO 2 as a solvent and Swelling Agent at 35.0 °C, and then the polymerization and crosslinking were carried out at 120 °C. The composition of the IPNs can be controlled by SC CO 2 pressure, concentrations of St and DVB in the fluid phase. Transmission electron microscopy shows that the PS is homogeneously dispersed in the IPNs and its phase size is in the range of 20–30 nm. The impact strength, tensile strength, and elongation-at-break of the PP/PS IPNs increase with increasing PS percentage in the IPNs.
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synthesis of composites of silicon rubber and polystyrene using supercritical co2 as a Swelling Agent
Journal of Materials Chemistry, 2002Co-Authors: Zhimin Liu, Buxing Han, Xinhua Dai, Guanying Yang, Zexuan Dong, Jiaqiu Wang, Xiaoli ZhangAbstract:The heterogeneous free-radical polymerization of styrene within supercritical carbon dioxide swollen silicon rubber film has been conducted to prepare the silicon rubber/polystyrene (SR/PS) polymer blends. The PS content in the blends can be controlled by adjusting the soaking time and the concentration of styrene in the supercritical fluid. Scanning electron microscopy (SEM) indicates that the PS phase is uniformly distributed in the blends and the phase size is very small (100 nm to 300 nm), although the two polymers are very different and incompatible. The mechanical properties of the blends and the average molecular weight of the PS polymerized in the matrix were also measured. The results indicate that the average molecular weight of the PS in the blend depends on the PS content or its phase size. The tensile strength of the blends is higher than that of original SR substrate, and there is a maximum in tensile strength vs. PS content. The Young's modulus of the blends increases monotonously with PS content in the blends.
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Grafting of methyl methylacrylate onto isotactic polypropylene film using supercritical CO2 as a Swelling Agent
Polymer, 2002Co-Authors: Zhimin Liu, Xinhua Dai, Liping Song, Guanying Yang, Buxing HanAbstract:Abstract Grafting of methyl methacrylate (MMA) onto isotactic polypropylene (iPP) film was carried out by free radical polymerization using supercritical (SC) carbon dioxide (SC CO2) as a solvent and Swelling Agent. The iPP film was first impregnated with the monomer MMA and initiator benzoyl peroxide (BPO) using SC CO2 at 308.15 K. After releasing CO2, the MMA molecules in the film were grafted onto the iPP at a higher reaction temperature. Using this method, the grafting level and the morphology can be controlled by the soaking time, pressure and concentrations of MMA and BPO in the fluid phase. The products were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and wide angle X-ray diffraction (WAXD).
