Characterization of starch films containing starch nanoparticles. Part 2: Viscoelasticity and creep properties
- Authors: Shi, Aimin , Wang, Li-jun , Li, Dong , Adhikari, Benu
- Date: 2013
- Type: Text , Journal article
- Relation: Carbohydrate Polymers Vol. 96, no. 2 (2013), p. 602-610
- Full Text: false
- Reviewed:
- Description: Starch films were successfully produced by incorporating spray dried and vacuum-freeze dried starch nanoparticles. The frequency sweep, creep-recovery behavior and time-temperature superposition (TTS) on these films were studied. All these films exhibited dominant elastic behavior (than viscous behavior) over the entire frequency range (0.1-100 rad/s). The incorporation of both types of starch nanoparticles increased the storage and loss modulus, tan δ, creep strain, creep compliance and creep rate at long time frame and reduced the recovery rate of films while the effect of different kinds of starch nanoparticles on these parameters was similar both in magnitude and trend. TTS method was successfully used to predict long time (over 20 days) creep behavior through the master curves. The addition of these nanoparticles could increase the activation energy parameter used in TTS master curves. Power law and Burger's models were capable of fitting storage and loss modulus (R2 > 0.79) and creep data (R2 > 0.96), respectively. © 2012 Elsevier Ltd. All rights reserved.
- Description: C1
The inactivation kinetics of polyphenol oxidase in mushroom (Agaricus bisporus) during thermal and thermosonic treatments
- Authors: Cheng, X. , Zhang, Min , Adhikari, Benu
- Date: 2013
- Type: Text , Journal article
- Relation: Ultrasonics Sonochemistry Vol. 20, no. 2 (2013), p. 674-679
- Full Text: false
- Reviewed:
- Description: The effect of thermal and thermosonic treatments on the inactivation kinetics of polyphenol oxidase (PPO) in mushroom (Agaricus bisporus) was studied in 55-75°C temperature range. In both the processes, the inactivation kinetics of PPO followed a first-order kinetics (R2 = 0.941-0.989). The D values during thermal inactivation varied from 112 ± 8.4 min to 1.2 ± 0.07 min while they varied from 57.8 ± 6.1 min to 0.88 ± 0.05 min during thermosonic inactivation at the same temperature range. The activation energy during thermal inactivation was found to be 214 ± 17 kJ/mol, while it was 183 ± 32 kJ/mol during thermosonic inactivation. The inactivating effect of combined ultrasound and heat was found to synergistically enhance the inactivation kinetics of PPO. The D values of PPO decreased by 1.3-3 times during thermosonic inactivation compared to the D values of PPO during thermal inactivation at the temperature range. Therefore, thermosonication can be further developed as an alternative to "hot break" process of mushroom. © 2012 Elsevier B.V. All rights reserved.
- Description: 2003010582
Effect of pore diffusion on the gasification characteristics of coal char under CO2 atmosphere
- Authors: Shahabuddin, M. , Kibria, M. , Bhattacharya, Sankar
- Date: 2021
- Type: Text , Journal article
- Relation: International Journal of Energy for a Clean Environment Vol. 22, no. 5 (2021), p. 85-102
- Full Text:
- Reviewed:
- Description: The effect of pore diffusion on kinetic parameters is of particular interest to the current study using coal char under CO2 gasification conditions. A high-temperature entrained-flow gasifier was used for the preparation of char through the rapid pyrolysis process. The kinetic study with the char was then carried at temperatures of 973-1473 K under atmospheric pressure. A prediction of carbon conversion for large particle size (100 μm) is reported from the carbon conversion of small particle size (25 μm) considering the diffusion effect. The effect of diffusion caused by temperatures and particle size was reported through activation energy. The apparent activation energy in the chemically controlled region (973-1173 K) was calculated to be 178 kJ/mol, whereas it was 69 kJ/mol in the pore diffusion zone (1373-1473 K) using smaller particle size. The apparent activation energy using large particle size was found to be 186 and 99 kJ/mol in chemically controlled and pore diffusion zone, respectively. The intrinsic activation energy for both particle sizes was almost similar. A variation between apparent and intrinsic reaction rates was depicted mostly at higher temperatures of over 1273 K. The change in the surface area of char particle was crucial in terms of decreasing reaction rates, which was decreased with the progression of the conversion. The predicted carbon conversion for large particle size was in good agreement with the experimentally measured conversion except for little discrepancies at higher temperatures. © 2021 by Begell House, Inc.