The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Sundaram Gunasekaran - One of the best experts on this subject based on the ideXlab platform.
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mechanical spectra and calorimetric evaluation of gelatin xanthan gum systems with high levels of co solutes in the glassy state
Food Hydrocolloids, 2013Co-Authors: Filiz Altay, Sundaram GunasekaranAbstract:Mechanical properties of gelatinexanthan gum (XG) mixtures with high levels of co-solutes were examined by dynamic mechanical analysis (DMA). The mechanical spectra of the samples were modeled according to the WilliamseLandeleFerry (WLF) equation/free-volume theory, which requires an entropic lightly cross-linked network. For the a dispersion, E 0 and E00 superposed with the horizontal Shift Factor aT, which was temperature-dependent according to the WLF equation; no other secondary dispersion mechanism was detected. The addition of XG to gelatin networks with high levels of co-solutes changed the glass transition temperature (Tg) and kinetics of glass transition and glassy states. In the glassy state, the WLF equation was unable to follow progress in the mechanical properties, which were better described by the Andrade equation. The calorimetric measurements of the gelatineXG systems were made using a modulated temperature differential scanning calorimetry (MTDSC) to improve the determination of Tg. The samples were exposed to two cooling and heating cycles to provide a controlled recent thermal history in the temperature range of 40 � Ct o� 70 � C. The Tg values of the samples were determined from the second heating cycle in the reversing heat signal. The calorimetric Tg values increased with increasing glucose syrup:sucrose ratio due to increased crosslinking, whereas mechanical Tg decreased with increased XG content due to network formation.
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rheological evaluation of gelatin xanthan gum system with high levels of co solutes in the rubber to glass transition region
Food Hydrocolloids, 2012Co-Authors: Filiz Altay, Sundaram GunasekaranAbstract:Effects of moisture content, xanthan gum (XG) addition, and glucose syrup (GS):sucrose ratio on the gelation of gelatin-XG systems with high levels of co-solutes were investigated in the rubbery and the glass transition regions. Frequency sweep tests were performed between 0.1 and 100 rad and the storage (G 0) and loss (G00) moduli of the system were measured in the temperature range of 60 to � 15 � C. The onset of glass transition region increased with decreasing moisture content. The timeetemperature superposition yielded master curves of G 0 and G00 as a function of timescale of measurement. G00 and G 00 were superimposed with the horizontal Shift Factor aT, which was temperature dependent according to the WilliamseLandeleFerry (WLF) equation. Glass transition temperature (Tg) of the samples were determined by dynamic mechanical analysis (DMA) from the peak of tan d. Tg decreased with XG addition. The energy of vitrification of samples with XG increased compared to samples containing only gelatin. Relaxation spectra of the samples were calculated from rheological measurements using the first and second approximations. The Rouse theory was more closely followed with the second approximation.
Bingzheng Jiang - One of the best experts on this subject based on the ideXlab platform.
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brittle tough transition in pp epdm blends effects of interparticle distance and temperature
Polymer, 1998Co-Authors: Wei Jiang, Changhai Liu, Zhigang Wang, Haojun Liang, Bingzheng Jiang, Xuehui Wang, Huixuan ZhangAbstract:Abstract The toughness of PP/EPDM blends was measured over a wide range of temperature (25–132°C) and composition 0–26 wt% EPDM). It was found that increasing temperature and decreasing interparticle distance have equivalent effects on the brittle-tough transition of toughening PP with EPDM, and the Shift Factor increases with increasing temperature. A correlation was also found between temperature and critical interparticle distance. When critical interparticle distance was plotted versus T g − T , where T g is defined as the brittle-tough transition temperature of the matrix itself, the curves for different blends systems converge to a single master curve.
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interparticle distance temperature strain rate equivalence for the brittle tough transition in polymer blends
Polymer, 1998Co-Authors: Wei Jiang, Haojun Liang, Bingzheng JiangAbstract:From the angle of energy transformation an equation was obtained for the brittle transition in polymer blends. The effects of interparticle distance, temperature and strain rate on the brittle-tough transition in polymer blends were characterized by this equation. The calculations show that, for this transition: (1) increasing temperature and decreasing interparticle distance are equivalent and the Shift Factor increases with increasing temperature; (2) decreasing strain rate and decreasing interparticle distance have equivalent effects on the transition; (3) the strain rate must be optimum in order to find the brittle-tough transition phenomena for a given temperature region. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.
Filiz Altay - One of the best experts on this subject based on the ideXlab platform.
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mechanical spectra and calorimetric evaluation of gelatin xanthan gum systems with high levels of co solutes in the glassy state
Food Hydrocolloids, 2013Co-Authors: Filiz Altay, Sundaram GunasekaranAbstract:Mechanical properties of gelatinexanthan gum (XG) mixtures with high levels of co-solutes were examined by dynamic mechanical analysis (DMA). The mechanical spectra of the samples were modeled according to the WilliamseLandeleFerry (WLF) equation/free-volume theory, which requires an entropic lightly cross-linked network. For the a dispersion, E 0 and E00 superposed with the horizontal Shift Factor aT, which was temperature-dependent according to the WLF equation; no other secondary dispersion mechanism was detected. The addition of XG to gelatin networks with high levels of co-solutes changed the glass transition temperature (Tg) and kinetics of glass transition and glassy states. In the glassy state, the WLF equation was unable to follow progress in the mechanical properties, which were better described by the Andrade equation. The calorimetric measurements of the gelatineXG systems were made using a modulated temperature differential scanning calorimetry (MTDSC) to improve the determination of Tg. The samples were exposed to two cooling and heating cycles to provide a controlled recent thermal history in the temperature range of 40 � Ct o� 70 � C. The Tg values of the samples were determined from the second heating cycle in the reversing heat signal. The calorimetric Tg values increased with increasing glucose syrup:sucrose ratio due to increased crosslinking, whereas mechanical Tg decreased with increased XG content due to network formation.
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rheological evaluation of gelatin xanthan gum system with high levels of co solutes in the rubber to glass transition region
Food Hydrocolloids, 2012Co-Authors: Filiz Altay, Sundaram GunasekaranAbstract:Effects of moisture content, xanthan gum (XG) addition, and glucose syrup (GS):sucrose ratio on the gelation of gelatin-XG systems with high levels of co-solutes were investigated in the rubbery and the glass transition regions. Frequency sweep tests were performed between 0.1 and 100 rad and the storage (G 0) and loss (G00) moduli of the system were measured in the temperature range of 60 to � 15 � C. The onset of glass transition region increased with decreasing moisture content. The timeetemperature superposition yielded master curves of G 0 and G00 as a function of timescale of measurement. G00 and G 00 were superimposed with the horizontal Shift Factor aT, which was temperature dependent according to the WilliamseLandeleFerry (WLF) equation. Glass transition temperature (Tg) of the samples were determined by dynamic mechanical analysis (DMA) from the peak of tan d. Tg decreased with XG addition. The energy of vitrification of samples with XG increased compared to samples containing only gelatin. Relaxation spectra of the samples were calculated from rheological measurements using the first and second approximations. The Rouse theory was more closely followed with the second approximation.
Wei Jiang - One of the best experts on this subject based on the ideXlab platform.
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brittle tough transition in pp epdm blends effects of interparticle distance and temperature
Polymer, 1998Co-Authors: Wei Jiang, Changhai Liu, Zhigang Wang, Haojun Liang, Bingzheng Jiang, Xuehui Wang, Huixuan ZhangAbstract:Abstract The toughness of PP/EPDM blends was measured over a wide range of temperature (25–132°C) and composition 0–26 wt% EPDM). It was found that increasing temperature and decreasing interparticle distance have equivalent effects on the brittle-tough transition of toughening PP with EPDM, and the Shift Factor increases with increasing temperature. A correlation was also found between temperature and critical interparticle distance. When critical interparticle distance was plotted versus T g − T , where T g is defined as the brittle-tough transition temperature of the matrix itself, the curves for different blends systems converge to a single master curve.
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interparticle distance temperature strain rate equivalence for the brittle tough transition in polymer blends
Polymer, 1998Co-Authors: Wei Jiang, Haojun Liang, Bingzheng JiangAbstract:From the angle of energy transformation an equation was obtained for the brittle transition in polymer blends. The effects of interparticle distance, temperature and strain rate on the brittle-tough transition in polymer blends were characterized by this equation. The calculations show that, for this transition: (1) increasing temperature and decreasing interparticle distance are equivalent and the Shift Factor increases with increasing temperature; (2) decreasing strain rate and decreasing interparticle distance have equivalent effects on the transition; (3) the strain rate must be optimum in order to find the brittle-tough transition phenomena for a given temperature region. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.
Valery Normand - One of the best experts on this subject based on the ideXlab platform.
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maltodextrin molecular weight distribution influence on the glass transition temperature and viscosity in aqueous solutions
Carbohydrate Polymers, 2004Co-Authors: F. Avaltroni, Pierreetienne Ouquerand, Valery NormandAbstract:Abstract The intrinsic functional properties (viscosity and glass transition temperature) of three corn maltodextrins (and their mixtures) in various amount of water are predicted from the molecular weight distribution. The concentration dependence of the viscosity at constant temperature is predicted over a broad range of concentration using a combination of the Mark–Houwink–Sakurada (with a rather low exponent (0.337) compared to other carbohydrates) and Spurlin–Martin–Tennent's exponential models. The construction of a viscosity–concentration master-curve is successfully attempted when the Shift Factor is the viscosity average molecular weight. The glass transition temperature for dry maltodextrin samples is predicted in the light of previous investigations performed on the series of maltose oligomers. A new effective average molecular weight, characteristic of the glass temperature, is introduced and determined by the plasticizer/plasticized ratio. Couchman's model is well adapted to starch water systems and is proven here to be also appropriate for maltodextrin water mixtures where the heat capacity increment depends on the number average molecular weight.
