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Activation Temperature (activation + temperature)
Selected AbstractsInfluence of Activation Temperature on Reaction Kinetics in Recycled Clay Waste,Calcium Hydroxide SystemsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2008Moisés Frías Obtaining pozzolanic materials from recycling of industrial waste and byproducts is a priority action of environmental policy all over the world. This paper describes the effect of activation conditions on the reaction kinetics in calcined clay waste (CCW)/calcium hydroxide systems. The CCW used in this work shows excellent qualities for use as supplementary cementing material in the manufacture of commercial blended cements. This research work presents an exhaustive study about the kinetics of a pozzolanic reaction in this cementing system. The results obtained by different techniques (DTA/TG, X-ray diffraction, and SEM/EDAX) confirm that the activation conditions (in the range 700°,800°C and 2,5 h of retention) have a direct effect on the formation and evolution of hydrated phases. Low activation temperatures favor the CSH gels' formation, while at higher temperatures aluminates (C4AH13) and aluminum silicate hydrates (C4ASH8, hydrotalcites) are predominant. [source] Short chain branching profiles in polyethylene from the Phillips Cr/silica catalystJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 15 2007Paul J. DesLauriers Abstract SEC and on-line Fourier transform infrared spectroscopy analysis have been combined to study branching profiles from the Phillips Cr/silica catalyst. For the first time, catalyst and reactor variables have been shown to affect the overall level and distribution of branches in polyethylene copolymers. Branching profiles from various chromium catalysts have been shown to vary from highly concentrated in the low MW end, to uniformly distributed over all of the MW range. Activation temperature and the presence of titania were highly influential. These observations, which have been used to gain insight into the chemistry of Cr/silica, explain much of the catalyst behavior that has for decades been used to optimize polymer properties. Trends in ESCR, impact resistance, and other physical characteristics, which were long attributed to changes in MW distribution, can now be seen to also be due in large part to changes in the branching profile. This knowledge should be of value in designing future resins. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3135,3149, 2007 [source] Determination of activation temperature of glass bulb sprinklers using a thermal liquid bathFIRE AND MATERIALS, Issue 4 2006Mohammed M. Khan Abstract A thermal liquid bath was used to determine the activation temperature of a wide range of temperature rated (57,182°C) glass bulb (3 and 5 mm diameters) sprinklers using water and glycerine. An optical switch and a thermocouple were installed adjacent to each sprinkler (within 10 mm) to record the activation of each glass bulb in the liquid bath having a uniform temperature distribution (±0.5°C). All the tests for determining the activation temperatures of glass bulb sprinklers were conducted in the liquid bath using a 0.277°C/min rate of temperature rise. Based on a heat transfer analysis, this rate is within the maximum allowable rate of rise of water and glycerine temperatures, which allows the glass bulb temperature to closely follow the liquid temperature. The sprinkler activation temperature was evaluated in terms of percentage rating, which is expressed as the percent variation of the average activation temperature, as measured in the liquid bath, from the nominal rated temperature. Sprinklers (93°C rated or lower) activation temperatures in water were consistently within ±3.5% of rating. In glycerine, the activation temperatures of sprinklers rated between 93 and 182°C performed within 3.5% of their rating. Copyright © 2005 John Wiley & Sons, Ltd. [source] Effect of activation temperature on pore development in activated carbon produced from palm shellJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 1 2003Wan Mohd Ashri Wan Daud Abstract A series of experiments were conducted to investigate the effect of activation temperature on pore development of activated carbon produced from palm shell. Activation of the samples was carried out at 800, 850 and 900,°C for different durations ranging from 10 to 180,min. The samples were characterized using N2 adsorption for evaluation of micropores and the mercury intrusion technique for mesopore and macropore analysis. Within the range of activation temperatures studied, high burn-off products derived from high activation temperatures tend to have larger micropore development. However, an increase in the activation temperature has no remarkable effect on mesopore and macropore development. © 2002 Society of Chemical Industry [source] Pore-size effects on activated-carbon capacities for volatile organic compound adsorptionAICHE JOURNAL, Issue 8 2002Mei-Chiung Huang Gas-phase adsorption of acetone and n-hexane by activated carbons with different pore structures was investigated. The carbons were prepared from a bituminous coal with KOH activation. Increasing the activation temperature increased both the porosity and pore size. The equilibrium adsorption capacity for the organic compounds increased with the carbon porosity, but not proportionally. The percentage of pore volume utilized showed a decreasing trend with the porosity development for acetone adsorption, while an increasing trend was observed for n-hexane. By incorporating pore size distribution with the Dubinin-Radushkevich equation using an inverse proportionality between the micropore size and adsorption energy, the isotherms for adsorption onto different carbons can be well predicted. Simulations indicated that the adsorption energy, which is an inverse function of the micropore size, determines the adsorption capacity. Different effects of porosity development were observed for different adsorbates. [source] Versatile preparation of poly(1,4-phenylenevinylene- co -1,4-phenylene-1,2-ethanediyl) by CVD polymerization of p -(methoxymethyl)benzyl chlorideJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 4 2005Ngo Trinh Tung Abstract It was demonstrated that a series of copolymers consisting of 1,4-phenylenevinylene (PV) and 1,4-phenylene-1,2-ethanediyl (PE) units could be prepared from a single monomer, p -(methoxymethyl)benzyl chloride, via the chemical vapor deposition polymerization (CVDP) method. The composition of the copolymers could be varied simply by altering the monomer activation temperature. The higher the temperature, the lower the content of the PV unit. The photo (PL)- and electroluminescence (EL) properties of the copolymers that revealed a blueshift when compared with PPV strongly depend on the amount of the PE units incorporated. The external quantum efficiencies of the electroluminescence devices having the configuration of ITO/PEDOT-PSS/copolymer/Al-Li were higher than that of PPV, which can be ascribed to the improved confinement of excitons. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 742,751, 2005 [source] Equilibrium and kinetic study for the removal of malachite green using activated carbon prepared from Borassus flabellofer male flowerASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2010P. E. Jagadeesh Babu Abstract Activated carbon was prepared from dried Borassus flabellofer male flower and batch adsorption experiments were conducted to study its potential to remove malachite green (MG) dye. The process was further optimized by studying the operating variables like initial pH of the stock solution, activation temperature, initial dye concentration, adsorbent loading and contact time. The optimized pH and activation temperatures were found to be 7.55 and 450 °C respectively, where further analysis was made using these optimal variables. Linear, Freundlich and Langmuir isotherms were studied and it was found that the Langmuir isotherms have the highest correlation coefficients compared to the others. Further, the sorption kinetics were analysed using pseudo-first-order and pseudo-second-order kinetic models. The data showed that the second-order equation was the more appropriate, which indicate that the intra-particle diffusion is the rate limiting factor. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Determination of activation temperature of glass bulb sprinklers using a thermal liquid bathFIRE AND MATERIALS, Issue 4 2006Mohammed M. Khan Abstract A thermal liquid bath was used to determine the activation temperature of a wide range of temperature rated (57,182°C) glass bulb (3 and 5 mm diameters) sprinklers using water and glycerine. An optical switch and a thermocouple were installed adjacent to each sprinkler (within 10 mm) to record the activation of each glass bulb in the liquid bath having a uniform temperature distribution (±0.5°C). All the tests for determining the activation temperatures of glass bulb sprinklers were conducted in the liquid bath using a 0.277°C/min rate of temperature rise. Based on a heat transfer analysis, this rate is within the maximum allowable rate of rise of water and glycerine temperatures, which allows the glass bulb temperature to closely follow the liquid temperature. The sprinkler activation temperature was evaluated in terms of percentage rating, which is expressed as the percent variation of the average activation temperature, as measured in the liquid bath, from the nominal rated temperature. Sprinklers (93°C rated or lower) activation temperatures in water were consistently within ±3.5% of rating. In glycerine, the activation temperatures of sprinklers rated between 93 and 182°C performed within 3.5% of their rating. Copyright © 2005 John Wiley & Sons, Ltd. [source] Effect of activation temperature on pore development in activated carbon produced from palm shellJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 1 2003Wan Mohd Ashri Wan Daud Abstract A series of experiments were conducted to investigate the effect of activation temperature on pore development of activated carbon produced from palm shell. Activation of the samples was carried out at 800, 850 and 900,°C for different durations ranging from 10 to 180,min. The samples were characterized using N2 adsorption for evaluation of micropores and the mercury intrusion technique for mesopore and macropore analysis. Within the range of activation temperatures studied, high burn-off products derived from high activation temperatures tend to have larger micropore development. However, an increase in the activation temperature has no remarkable effect on mesopore and macropore development. © 2002 Society of Chemical Industry [source] Influence of Activation Temperature on Reaction Kinetics in Recycled Clay Waste,Calcium Hydroxide SystemsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2008Moisés Frías Obtaining pozzolanic materials from recycling of industrial waste and byproducts is a priority action of environmental policy all over the world. This paper describes the effect of activation conditions on the reaction kinetics in calcined clay waste (CCW)/calcium hydroxide systems. The CCW used in this work shows excellent qualities for use as supplementary cementing material in the manufacture of commercial blended cements. This research work presents an exhaustive study about the kinetics of a pozzolanic reaction in this cementing system. The results obtained by different techniques (DTA/TG, X-ray diffraction, and SEM/EDAX) confirm that the activation conditions (in the range 700°,800°C and 2,5 h of retention) have a direct effect on the formation and evolution of hydrated phases. Low activation temperatures favor the CSH gels' formation, while at higher temperatures aluminates (C4AH13) and aluminum silicate hydrates (C4ASH8, hydrotalcites) are predominant. [source] Equilibrium and kinetic study for the removal of malachite green using activated carbon prepared from Borassus flabellofer male flowerASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2010P. E. Jagadeesh Babu Abstract Activated carbon was prepared from dried Borassus flabellofer male flower and batch adsorption experiments were conducted to study its potential to remove malachite green (MG) dye. The process was further optimized by studying the operating variables like initial pH of the stock solution, activation temperature, initial dye concentration, adsorbent loading and contact time. The optimized pH and activation temperatures were found to be 7.55 and 450 °C respectively, where further analysis was made using these optimal variables. Linear, Freundlich and Langmuir isotherms were studied and it was found that the Langmuir isotherms have the highest correlation coefficients compared to the others. Further, the sorption kinetics were analysed using pseudo-first-order and pseudo-second-order kinetic models. The data showed that the second-order equation was the more appropriate, which indicate that the intra-particle diffusion is the rate limiting factor. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] | |||||||||||||