Papers by Keyword: Arrhenius Equation

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Authors: H.D. Mepba, T. Ademiluyi
Abstract: Procedures for the preparation and rheological characterisation of coconut milk yoghurts are described. Coconut milk was fortified with soymilk, 50:50 (v/v/)% (coconut milk:soymilk), Nonfat dry milk, 60:40 (coconut milk:Nonfat dry milk), while whole coconut milk served as control. Milk preparations were homogenized, heated to 40, 60 and 80oC for 30 mins, inoculated with Streptococcus thermophilus and Lactobacillus bulgaricus and incubated at 43oC to attain pH 4.6. Rheological properties of yoghurts were studied at temperatures ranging from 10 – 80oC. All samples exhibited a pseudo plastic behaviour and described by a power law model. The effect of temperature on apparent viscosity was explained by a polynomial equation and gave a better fit than the Arrhenius relationship. The consistency coefficient exhibits strong dependence on temperature for which the activation energy of flow ranged from 4.57– 6.47kJ/mol. The flow behaviour index was low and nearly constant (~ 0.78) up to 40oC and then decreased with further increase in temperature.
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Authors: H. Shivananda Nayaka, Gajanan P. Chaudhari, B.S. Sunder Daniel
Abstract: A detailed study was performed on the grain growth kinetics of ultrafine-grained AZ61 magnesium alloy produced by accumulative roll bonding by carrying out isothermal annealing treatments on the roll bonded samples. Annealing treatments were carried out in the temperature range 423 to 573K for 2 to 120 minutes. As the annealing time and temperature increased, the grain size increased. The effect of annealing temperature and time, on the grain growth can be well explained by the kinetic equation and Arrhenius equation. Based on the experimental results of grain growth during annealing treatments, the grain growth exponent and the activation energy for grain growth were determined. The grain growth kinetic parameters were compared with other magnesium alloys processed by various methods.
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Authors: Jun Seong Park, Dae Hee Yun, Tae Won Ko, Yong Sung Park, Je Wan Woo
Abstract: The kinetics of the Diels-Alder reaction of cyclopentadiene with bis(2-ethylhexyl) maleate has been studied at temperatures between 25 and 100 °C and at atmospheric pressure. The influence of temperature on the kinetic constants was determined by fitting the results to the Arrhenius equation. As a result, fitting line similar with the linear curve of the Arrhenius equation at 25, 30 and 40 °C. However, the fitting curve, at 60, 80 and 100 °C, tended towards the outside of the curve in the form of Arrhenius equation. The ratio of endo/exo was a slight change from increase of the reaction temperature.
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Authors: Lyudmila N. Paritskaya, V.V. Bogdanov, Yuri S. Kaganovsky, Witold Łojkowski
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Authors: Guo Jun Song, Yang Li, Pei Yao Li, Zheng Gu, Jian Guo Gao, Chang Yong Sun, Wen Zhe Song, Gang Wang, Long Liang Cong
Abstract: Thermo-gravimetric technology was used to rapidly evaluate and measure safe use life of food contact polymer materials. The thermo-gravimetric curve showed that silicone rubber pad decomposition temperature was about 350°C in air and the maximum decomposition rate was 450°C. 370°C, 380°C, 390°C, 400°C, 410°C at the right temperature zone was chosen to do thermo-gravimetric constant temperature experiments; the time of silicon rubber pad’s weightlessness of 5%, 10% 15% was calculated by the above curve, respectively. Finally Arrhenius equation was used to establish the relationship between temperature and time; and then the result of infer silicone rubber pad using life was 1.37 thousand times when it was used as a baking tray.
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Authors: Y. Harada, M. Ohmori, Lei Wang
Abstract: Serration phenomenon of sintered and cast chromium was investigated by means of tension test at various strain rates. With increasing test temperature, tensile strength decreased gradually at first and showed a minimum at a certain temperature. Above this temperature, the strength continued to increase to a maximum value. Serrated flow appeared between the temperatures of the minimum and maximum tensile strengths. Tensile ductility minimum was also observed around the temperature of the maximum tensile strength. Relation between the strain rate and the temperature T of the maximum tensile strength could be well described by an Arrhenius equation. Activation energy of 101.3kJ/mol found in the present study is in good agreement with the activation energy for diffusion of nitrogen atom in chromium.
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Authors: Jing Song Wang, Shu You Huang, Li Jun Cao, Hao Yan Sun, Jing Hua Wang, Qing Guo Xue
Abstract: In this paper, the viscosity of molten Zr50Cu50 alloy was measured by using NaF-CaF2 covering slag protection combining rotating cylinder method firstly under non-vacuum melting condition. The curve of viscosity and temperature was acquired stably in the temperature range from 1370K to the liquidus temperature (1208K). According the Arrhenius equation form, the viscosity-temperature relation of molten Zr50Cu50 alloy can be fit as the following equation: (1208K50 alloy can be calculated by the above equation in the range of 1370 to 1208K. The viscosity values of molten Zr50Cu50 alloy calculated by Hirai model are relatively small, so the corrected Hirai model was obtained by the measured viscosity data. The viscosities of molten Zr-Cu alloys can be expressed by the following corrected Hirai model: The viscosities of typical molten Zr-Cu alloys were calculated by the above corrected model. The results showed that the viscosities of Zr-Cu alloys are larger at the respective liquidus temperature. The fundamental data were provided for researching the relationship between viscosities of molten Zr-Cu alloys and amorphous form ability.
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Authors: Reymark D. Maalihan, Bryan B. Pajarito
Abstract: This work reports the effect of temperature on degradation of colored low-density polyethylene (PE) films during thermal aging. Film samples were formulated according to Taguchi design of experiments where colorant, thickness, and pro-oxidant concentration were varied accordingly. Tensile properties of films were monitored with time during heat aging in a hot air oven at 50, 70, and 90 °C. Likewise, surfaces of aged films were analyzed to evaluate the degree of oxidation of PE during thermal aging. The Arrhenius equation was then used to predict the lifetime of PE at an in-use temperature of 30 °C. Results indicate that increasing the temperature reduces the tensile strength and modulus of films. Formation of carbonyl groups as degradation products is also observed at higher temperatures. Consequently, thermal aging at 90 °C offers the highest extent of degradation of exposed films. Regression analysis reveals that white films degrade at a higher rate than yellow and non-colored films. The presence of TiO2 in white films shortens the lifetime of PE while amine stabilizer in yellow films enhances the stability of PE during thermal aging.
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