The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
Wan Shik Ha - One of the best experts on this subject based on the ideXlab platform.
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Realtime Characterization of In Situ Molecular Alignment during the Saponification Process of Polyvinyl Pivalate
Polymer Journal, 2000Co-Authors: Won Seok Lyoo, Wan Shik HaAbstract:The spontaneous fiber formation process during Saponification of poly(vinyl pivalate) (PVPi) with syndiotactic diad content 63 to 65% to poly(vinyl alcohol)(PVA) in the presence of water was in situ examined. The variation of the revolution per minute(rpm) of a torque apparatus under a constant torque was measured for the spontaneous fibrillation system, and the actual fibrillation system was visualized in the realtime scale by in-line photographing. The in situ fibrillation mechanism was accounted for by relating the variation of the rpm with proceeding the saponifecation reaction to the change of solution morphology with Saponification. At the constant torque level, the rpm changed with proceeding the Saponification reaction in a complicated way. Up to the Saponification time 80 s, the rpm was slightly increased with Saponification, then decreased to the Saponification time 400 s. From the Saponification time 400 s, however, the rpm was abruptly increased. Then, the rpm was levelled off after the Saponification time 700 s. Comparison of the rotational speed variation with the morphology change revealed that phase separation began from the degree of Saponification 72.8%, and a clear fibrillar structure appeared from the degree of Saponification 91.6%.
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in situ fibrillation of poly vinyl alcohol during Saponification of poly vinyl ester 1 chemorheological and morphological investigations of in situ fibrillation
Polymer, 1999Co-Authors: Won Seok Lyoo, Wan Shik HaAbstract:Abstract The syndiotacticity-rich (syndiotactic diad content of 57–65%) high molecular weight (number-average degree of polymerization of 4500–20000) poly(vinyl alcohol) (PVA) microfibrillar fiber was directly produced via the Saponification reaction of poly(vinyl pivalate) (PVPi) by controlling structural factors such as molecular weight and stereoregularity of PVA chains, and appetence between PVA and solvent without existing spinning procedures. By examining and observing the changes of flow birefringence, shear viscosity of reaction solution, degree of Saponification, and shape of reaction product during the Saponification reaction, the following novel formation mechanism of high strength microfibrillar PVA fiber is proposed. As PVPi converts into syndiotactic PVA by means of Saponification using saponifying agents containing water, an oriented gel structure appears first by the interaction between water and hydroxyl groups of syndiotactic PVA formed during the Saponification reaction, and then the microfibrillar structure is formed by the collapse of water-PVA interbridges and the resultant chain packing between syndiotactic PVA molecules. The larger the syndiotacticities of both PVPi and PVA, the higher the molecular orientation and the smaller the hydroxyl groups in P(VPi-VA) copolymer needed for in situ fibrillation. The well oriented microfibrillar PVA fiber prepared by such a manner had irregular cross-sections, needle-point-like ends, accumulated ultrafine microfibril structure.
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Spontaneous Orientation of Molecules during Saponification of Poly(vinyl pivalate)
Polymer Journal, 1998Co-Authors: Won Seok Lyoo, Wan Shik HaAbstract:Two kinds of poly(vinyl alcohol) (PVA) with assigned syndiotactic diad content, 52 to 53% (denoted as atactic) and 63 to 65% (denoted as syndiotactic), were prepared by low temperature UV-radiation bulk polymerization of vinyl acetate and vinyl pivalate, followed by saponifying the corresponding poly(vinyl acetate) (PVAc) and poly(vinyl pivalate) (PVPi), respectively. Saponification of PVPi produced highly crystalline and oriented PVA fibers whereas PVAc did not develop any fibrillar structure. The tacticity of the polymer seemed to play a significant role in the in situ fiber formation. Syndiotactic PVA gave positive yield stress while atactic PVA did not exhibit yield behavior. Relaxation time increased with syndiotactic content or molecular weight of polymer. Even by slight shearing between glass plates, syndiotactic PVA solutions readily developed a shear-induced fibrillar structure, while atactic PVA solutions did not exhibit any domain structure. Actual in situ fibrillation at the late stage of Saponification of PVPi was simulated by two syndiotactic (PVA)s of similar molecular weight but with different degrees of Saponification, 95.4 and 99.0%.
G. Nagarajan - One of the best experts on this subject based on the ideXlab platform.
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theoretical modeling of iodine value and Saponification value of biodiesel fuels from their fatty acid composition
Renewable Energy, 2009Co-Authors: Ashwin Gopinath, Sukumar Puhan, G. NagarajanAbstract:Biodiesel is an alternative fuel consisting of alkyl esters of fatty acids from vegetable oils or animal fats. The properties of biodiesel depend on the type of vegetable oil used for the transesterification process. The objective of the present work is to theoretically predict the iodine value and the Saponification value of different biodiesels from their fatty acid methyl ester composition. The fatty acid ester compositions and the above values of different biodiesels were taken from the available published data. A multiple linear regression model was developed to predict the iodine value and Saponification value of different biodiesels. The predicted results showed that the prediction errors were less than 3.4% compared to the available published data. The predicted values were also verified by substituting in the available published model which was developed to predict the higher heating values of biodiesel fuels from their iodine value and the Saponification value. The resulting heating values of biodiesels were then compared with the published heating values and reported.
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Theoretical modeling of iodine value and Saponification value of biodiesel fuels from their fatty acid composition
Renewable Energy, 2009Co-Authors: Ashwin Gopinath, Sukumar Puhan, G. NagarajanAbstract:Biodiesel is an alternative fuel consisting of alkyl esters of fatty acids from vegetable oils or animal fats. The properties of biodiesel depend on the type of vegetable oil used for the transesterification process. The objective of the present work is to theoretically predict the iodine value and the Saponification value of different biodiesels from their fatty acid methyl ester composition. The fatty acid ester compositions and the above values of different biodiesels were taken from the available published data. A multiple linear regression model was developed to predict the iodine value and Saponification value of different biodiesels. The predicted results showed that the prediction errors were less than 3.4% compared to the available published data. The predicted values were also verified by substituting in the available published model which was developed to predict the higher heating values of biodiesel fuels from their iodine value and the Saponification value. The resulting heating values of biodiesels were then compared with the published heating values and reported. © 2008 Elsevier Ltd. All rights reserved.
Won Seok Lyoo - One of the best experts on this subject based on the ideXlab platform.
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Realtime Characterization of In Situ Molecular Alignment during the Saponification Process of Polyvinyl Pivalate
Polymer Journal, 2000Co-Authors: Won Seok Lyoo, Wan Shik HaAbstract:The spontaneous fiber formation process during Saponification of poly(vinyl pivalate) (PVPi) with syndiotactic diad content 63 to 65% to poly(vinyl alcohol)(PVA) in the presence of water was in situ examined. The variation of the revolution per minute(rpm) of a torque apparatus under a constant torque was measured for the spontaneous fibrillation system, and the actual fibrillation system was visualized in the realtime scale by in-line photographing. The in situ fibrillation mechanism was accounted for by relating the variation of the rpm with proceeding the saponifecation reaction to the change of solution morphology with Saponification. At the constant torque level, the rpm changed with proceeding the Saponification reaction in a complicated way. Up to the Saponification time 80 s, the rpm was slightly increased with Saponification, then decreased to the Saponification time 400 s. From the Saponification time 400 s, however, the rpm was abruptly increased. Then, the rpm was levelled off after the Saponification time 700 s. Comparison of the rotational speed variation with the morphology change revealed that phase separation began from the degree of Saponification 72.8%, and a clear fibrillar structure appeared from the degree of Saponification 91.6%.
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in situ fibrillation of poly vinyl alcohol during Saponification of poly vinyl ester 1 chemorheological and morphological investigations of in situ fibrillation
Polymer, 1999Co-Authors: Won Seok Lyoo, Wan Shik HaAbstract:Abstract The syndiotacticity-rich (syndiotactic diad content of 57–65%) high molecular weight (number-average degree of polymerization of 4500–20000) poly(vinyl alcohol) (PVA) microfibrillar fiber was directly produced via the Saponification reaction of poly(vinyl pivalate) (PVPi) by controlling structural factors such as molecular weight and stereoregularity of PVA chains, and appetence between PVA and solvent without existing spinning procedures. By examining and observing the changes of flow birefringence, shear viscosity of reaction solution, degree of Saponification, and shape of reaction product during the Saponification reaction, the following novel formation mechanism of high strength microfibrillar PVA fiber is proposed. As PVPi converts into syndiotactic PVA by means of Saponification using saponifying agents containing water, an oriented gel structure appears first by the interaction between water and hydroxyl groups of syndiotactic PVA formed during the Saponification reaction, and then the microfibrillar structure is formed by the collapse of water-PVA interbridges and the resultant chain packing between syndiotactic PVA molecules. The larger the syndiotacticities of both PVPi and PVA, the higher the molecular orientation and the smaller the hydroxyl groups in P(VPi-VA) copolymer needed for in situ fibrillation. The well oriented microfibrillar PVA fiber prepared by such a manner had irregular cross-sections, needle-point-like ends, accumulated ultrafine microfibril structure.
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Spontaneous Orientation of Molecules during Saponification of Poly(vinyl pivalate)
Polymer Journal, 1998Co-Authors: Won Seok Lyoo, Wan Shik HaAbstract:Two kinds of poly(vinyl alcohol) (PVA) with assigned syndiotactic diad content, 52 to 53% (denoted as atactic) and 63 to 65% (denoted as syndiotactic), were prepared by low temperature UV-radiation bulk polymerization of vinyl acetate and vinyl pivalate, followed by saponifying the corresponding poly(vinyl acetate) (PVAc) and poly(vinyl pivalate) (PVPi), respectively. Saponification of PVPi produced highly crystalline and oriented PVA fibers whereas PVAc did not develop any fibrillar structure. The tacticity of the polymer seemed to play a significant role in the in situ fiber formation. Syndiotactic PVA gave positive yield stress while atactic PVA did not exhibit yield behavior. Relaxation time increased with syndiotactic content or molecular weight of polymer. Even by slight shearing between glass plates, syndiotactic PVA solutions readily developed a shear-induced fibrillar structure, while atactic PVA solutions did not exhibit any domain structure. Actual in situ fibrillation at the late stage of Saponification of PVPi was simulated by two syndiotactic (PVA)s of similar molecular weight but with different degrees of Saponification, 95.4 and 99.0%.
Peiwu Li - One of the best experts on this subject based on the ideXlab platform.
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simultaneous determination of tocopherols carotenoids and phytosterols in edible vegetable oil by ultrasound assisted Saponification lle and lc ms ms
Food Chemistry, 2019Co-Authors: Liangxiao Zhang, Sujun Wang, Ruinan Yang, Jun Jiang, Xiupin Wang, Wen Zhang, Qi Zhang, Peiwu LiAbstract:Abstract A method was developed to simultaneously determine eight bioactive compounds in edible oil based on ultrasound-assisted Saponification, liquid-liquid extraction and liquid chromatography coupled with tandem mass spectrometry. Central composite design was employed to optimize ultrasonic temperature and time of Saponification. Sample treatment was conducted by ultrasound-assisted Saponification at temperature of 75 °C for 40 min. Limits of detection and limits of quantification ranged from 2.0 to 3.2 and from 6.1 to 10.0 ng/mL, respectively. Linear correlations were obtained (R2 > 0.99) and the recoveries at three spiked levels were between 81.7% and 112.0%. This method was employed to determine eight compounds in camellia oils and olive oils. As results, the contents of stigmasterol, δ-tocopherol, γ-tocopherol, β-carotene and lutein in camellia oils were significantly higher than those in olive oils (p
Ashwin Gopinath - One of the best experts on this subject based on the ideXlab platform.
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theoretical modeling of iodine value and Saponification value of biodiesel fuels from their fatty acid composition
Renewable Energy, 2009Co-Authors: Ashwin Gopinath, Sukumar Puhan, G. NagarajanAbstract:Biodiesel is an alternative fuel consisting of alkyl esters of fatty acids from vegetable oils or animal fats. The properties of biodiesel depend on the type of vegetable oil used for the transesterification process. The objective of the present work is to theoretically predict the iodine value and the Saponification value of different biodiesels from their fatty acid methyl ester composition. The fatty acid ester compositions and the above values of different biodiesels were taken from the available published data. A multiple linear regression model was developed to predict the iodine value and Saponification value of different biodiesels. The predicted results showed that the prediction errors were less than 3.4% compared to the available published data. The predicted values were also verified by substituting in the available published model which was developed to predict the higher heating values of biodiesel fuels from their iodine value and the Saponification value. The resulting heating values of biodiesels were then compared with the published heating values and reported.
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Theoretical modeling of iodine value and Saponification value of biodiesel fuels from their fatty acid composition
Renewable Energy, 2009Co-Authors: Ashwin Gopinath, Sukumar Puhan, G. NagarajanAbstract:Biodiesel is an alternative fuel consisting of alkyl esters of fatty acids from vegetable oils or animal fats. The properties of biodiesel depend on the type of vegetable oil used for the transesterification process. The objective of the present work is to theoretically predict the iodine value and the Saponification value of different biodiesels from their fatty acid methyl ester composition. The fatty acid ester compositions and the above values of different biodiesels were taken from the available published data. A multiple linear regression model was developed to predict the iodine value and Saponification value of different biodiesels. The predicted results showed that the prediction errors were less than 3.4% compared to the available published data. The predicted values were also verified by substituting in the available published model which was developed to predict the higher heating values of biodiesel fuels from their iodine value and the Saponification value. The resulting heating values of biodiesels were then compared with the published heating values and reported. © 2008 Elsevier Ltd. All rights reserved.
