The relation of physical properties of native starch granules to the kinetics of amylolysis catalysed by porcine pancreatic α-amylase

AbstractThe physical properties and water absorption kinetics of three varieties of Mucuna beans (Mucuna pruriens, Mucuna rajada and Mucuna veracruz) were determined in this study. Physical properties including length, width, thickness, geometric mean diameter, sphericity, porosity, bulk density, area, volume and one thousand seed mass were calculated while hydration kinetics was studied by soaking Mucuna beans in water at 30 °C, 40 °C and 50 °C and measuring water uptake at 9 h interval. Peleg’s equation was used to model the hydration characteristics and Arrhenius equation was used to describe the effect of temperature on Peleg’s rate constant k1 and to obtain the activation energies for soaking. Significant variations were observed in almost all the physical properties of the different varieties, however, there were no significant differences (p < 0.05) in their thicknesses and bulk densities. The effectiveness of fit of Peleg’s model (R2) increased with increase in soaking temperature. Peleg’s rate constant k1 decreased with increase in soaking temperature while k2 increased with temperature increase. Activation energies of Mucuna pruriens, Mucuna rajada and Mucuna veracruz were 1613.24 kJ/mol, 747.95 kJ/mol and 2743.64 kJ/mol, respectively. This study provides useful information about the properties of three varieties of Mucuna beans that could be of importance to processors and engineers for process design and optimization.

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Vulcanization of Elastomers. 23. The Chemical Kinetics of Vulcanization Reactions and The Physical Properties of The Vulcanizates. I

Rubber Chemistry and Technology ◽

10.5254/1.3542149 ◽

1960 ◽

Vol 33 (2) ◽

pp. 335-341

Author(s):

Walter Scheele ◽

Karl-Heinz Hillmer

Keyword(s):

Activation Energy ◽

Physical Properties ◽

Chemical Kinetics ◽

Kcal Mole ◽

First Order ◽

Equilibrium Swelling ◽

Kinetics Of ◽

Kinetics Of Vulcanization ◽

Limiting Value ◽

Good Agreement

Abstract As a complement to earlier investigations, and in order to examine more closely the connection between the chemical kinetics and the changes with vulcanization time of the physical properties in the case of vulcanization reactions, we used thiuram vulcanizations as an example, and concerned ourselves with the dependence of stress values (moduli) at different degrees of elongation and different vulcanization temperatures. We found: 1. Stress values attain a limiting value, dependent on the degree of elongation, but independent of the vulcanization temperature at constant elongation. 2. The rise in stress values with the vulcanization time is characterized by an initial delay, which, however, is practically nonexistent at higher temperatures. 3. The kinetics of the increase in stress values with vulcanization time are both qualitatively and quantitatively in accord with the dependence of the reciprocal equilibrium swelling on the vulcanization time; both processes, after a retardation, go according to the first order law and at the same rate. 4. From the temperature dependence of the rate constants of reciprocal equilibrium swelling, as well as of the increase in stress, an activation energy of 22 kcal/mole can be calculated, in good agreement with the activation energy of dithiocarbamate formation in thiuram vulcanizations.

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Nitromethane - Physical Properties, Thermodynamics, Kinetics Of Decomposition, And Utilization As Fuel

Chemical Reviews ◽

10.1021/cr50022a002 ◽

1958 ◽

Vol 58 (4) ◽

pp. 627-644 ◽

Cited By ~ 30

Author(s):

A. Makovky ◽

L. Lenji

Keyword(s):

Physical Properties ◽

Kinetics Of Decomposition ◽

Kinetics Of

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Physical properties and growth kinetics of co-sputtered indium-zinc oxide films

Semiconductor Science and Technology ◽

10.1088/0268-1242/24/9/095019 ◽

2009 ◽

Vol 24 (9) ◽

pp. 095019 ◽

Cited By ~ 20

Author(s):

Changgang Huang ◽

Meili Wang ◽

Quanlin Liu ◽

Yongge Cao ◽

Zhonghua Deng ◽

...

Keyword(s):

Zinc Oxide ◽

Physical Properties ◽

Growth Kinetics ◽

Oxide Films ◽

Zinc Oxide Films ◽

Indium Zinc Oxide ◽

Kinetics Of

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Physical Properties and Non-Isothermal Crystallisation Kinetics of Primary Mechanically Recycled Poly(l-lactic acid) and Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

Polymers ◽

10.3390/polym13193396 ◽

2021 ◽

Vol 13 (19) ◽

pp. 3396

Author(s):

Luboš Běhálek ◽

Jan Novák ◽

Pavel Brdlík ◽

Martin Borůvka ◽

Jiří Habr ◽

...

Keyword(s):

Lactic Acid ◽

Physical Properties ◽

Structural Changes ◽

The Other ◽

Half Time ◽

Crystallisation Kinetics ◽

Isothermal Crystallisation ◽

Melt Crystallisation ◽

Kinetics Of ◽

Crystallisation Rate

The physical properties and non-isothermal melt- and cold-crystallisation kinetics of poly (l-lactic acid) (PLLA) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) biobased polymers reprocessed by mechanical milling of moulded specimens and followed injection moulding with up to seven recycling cycles are investigated. Non-isothermal crystallisation kinetics are evaluated by the half-time of crystallisation and a procedure based on the mathematical treatment of DSC cumulative crystallisation curves at their inflection point (Kratochvil-Kelnar method). Thermomechanical recycling of PLLA raised structural changes that resulted in an increase in melt flow properties by up to six times, a decrease in the thermal stability by up to 80 °C, a reduction in the melt half-time crystallisation by up to about 40%, an increase in the melt crystallisation start temperature, and an increase in the maximum melt crystallisation rate (up to 2.7 times). Furthermore, reprocessing after the first recycling cycle caused the elimination of cold crystallisation when cooling at a slow rate. These structural changes also lowered the cold crystallisation temperature without impacting the maximum cold crystallisation rate. The structural changes of reprocessed PHBV had no significant effect on the non-isothermal crystallisation kinetics of this material. Additionally, the thermomechanical behaviour of reprocessed PHBV indicates that the technological waste of this biopolymer is suitable for recycling as a reusable additive to the virgin polymer matrix. In the case of reprocessed PLLA, on the other hand, a significant decrease in tensile and flexural strength (by 22% and 46%, respectively) was detected, which reflected changes within the biobased polymer structure. Apart from the elastic modulus, all the other thermomechanical properties of PLLA dropped down with an increasing level of recycling.

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