The value of MPP is 244.3 kJ/mol, and the values for composites with sized glass fibres are 244.2, and 229.7 kJ/mol for CMPG and CMPU, respectively. The value for activationenergy for composite with unsized fibres is 255.5 kJ/mol and it is higher than MPP. Loweractivationenergy for composites with sized glass fibres indicate on relieved crystallization behavior compared to MPP.
increase the number of vacancies in the structure and favors the ionic mobility. Structural characterization shows that the obtained material have the expected tetragonal P4/mmm perovskite structure. Chemical analysis shows that compo- sition was homogeneus in all the sample. The bulk conductivity measured at room temperature is about the same as previously reported for its related lanthanum lithium titanate. However, the loweractivationenergy for ionic conduction encourages further searching for better conductors in this system.
Decrease the volume of the reaction container. There are fewer moles of gaseous product than moles of gaseous reactants; therefore, an increase in pressure due to a decrease in volume would favor the formation of product. Lower the temperature. A lower temperature favors an exothermic reaction, leading to the conversion of reactants into product.
(discussed in detail later). Thus we anticipate higher activationenergy values through the glass transition for amorphous trehalose compared to amorphous sucrose. Our second objective is based on the hypothesis that the difference in activationenergy for global mobility between the glassy and supercooled liquid states would be more for trehalose than for sucrose. In other words, the effect of temperature in reducing the activationenergy barrier for the glass to flow would be more in trehalose than in sucrose. Our third objective is to measure the minimum temperature of β-relaxation in amorphous sucrose and trehalose under similar experimental conditions (e.g., annealing time). Assuming that β-relaxations are the precursor to the glass transition or the global mobility, we hypothesize that the minimum temperature of β-relaxation would be more in trehalose compared to sucrose because amorphous trehalose has a higher T g than sucrose. Lastly, as an indirect proof of the thermally induced progression
Abstract: Carbon fiber is a kind of new polymer material with excellent mechanical properties and being applied widely. The process of carbon fiber prepared by bamboo tar, including extraction, condensation, spinning, oxidation and carbonation, is influenced by the pyrolysis kinetics significantly. In this paper, the thermogravimetric analysis (TGA) of bamboo tar produced in the process of pyrolysis and gasification of the bamboo which is known as Phylostachys sulphurea, was analyzed by the distributed activationenergy model (DAEM) to understand the kinetic properties and parameters of bamboo tar. The thermogravimetric analysis of bamboo tar which is used as the raw material of carbon fiber was conducted under 5 different heating rates (i.e. 5, 10, 15, 30 and 50 °C/min, etc.) in nitrogen atmosphere. The results show that the activationenergy of bamboo tar and the exponential factor increased significantly with the increase of the heating rate, and the low heating rate is advantageous to the extraction of bamboo tar solvent and the thermal polycondensation, which can provide scientific reference for the optimization of carbon fiber technology. The thermal weight results show that the temperature range of bamboo tar being decomposed rapidly is 213°C-410°C. The ranges of the activationenergy were calculated by DAEM, which have small difference in comparisons with five heating rates when the conversion rate is at 0.1-0.6 and the average value of the activationenergy is 119 kJ/mol. The stability range of the activationenergy is enlarged when the conversion rate is greater than 0.6 and heating rate increases.
The kinetic parameters calculated by Coats-Redfern method are listed in Table 4. The values of activationenergy and exponential factor calculated by Coats-Red- fern method compare respectively with the average value of activationenergy calculated using FWO method and the value of pre-exponential factor obtained by Kissinger method, the results are listed in Table 5.
photoconversion in additively colored KCl (0.35 eV), KBr (0.39 eV), and CsBr ( ∼ 0.1 eV). The "activation volumes" for F-to-M conversion in KCl and CsBr have been measured. They are much smaller than those estimated for free anion diffusion. The same mechanism for F-to-M conversion seems to obtain in these three salts.
Copyright to IJIRSET www.ijirset.com 4002 The apparent activationenergy Ea(induction period) was calculated from slope of the curve and is found to be 55.287 kJ mol -1 , and that of oscillation period for total oscillations Ea(Total oscillations) was 54.705 kJ mol -1 , while the apparent energy of activation for first 9 oscillations was found to be 35.303k J mol -1 . This data shows that the apparent energy of activation for induction period is slightly higher than the overall apparent energy of activation, although they could explain the difficulty degree of overall elementary reactions, Ea (induction) is comparable to Ea (Total oscillations) , they could illustrate the induction reaction is no more easier than that oscillation reaction which could be due to the presence of –sulphonic acid group at the para position. However the Ea value for first 9 oscillations is quite less.
not depend on the viscosity of the solvent. Hence, we may infer that the phenomenon of quenching is not solely controlled by material diffusion. Therefore, in addition to diffusion, it may also depend on the activation process. In order to see whether the activation process is playing a role, we have calculated the activationenergy (E a ) for the
The phrase often touted by politicians, “drill here, drill now,” could be a short term solution for energy independence if we can find about 9.7 million barrels per day of oil reserves domestically (Smith, 2011). The good news is that the United States has a large amount of oil reserves. The bad news is that there are many political and environmental obstacles to bring much of this oil to the surface. Most new oil discoveries are unconventional and located in shale formations. They require horizontal drilling and “fracking” to uncover. Some are located under restricted lands. The horizontal drilling and “fracking” involves drilling a vertical hole to the depth where the oil bearing shale is located, then drilling horizontally through the shale. As the well is drilled, it is also cased with steel pipe and cement. Once the well has been drilled, perforating charges are placed into the bore hole and detonated to create holes in the horizontal section of the casing pipe several thousand feet below the surface. After the casing pipe has been perforated, the fracking solution, which consists of a high volume of water, is pumped into the well at extremely high pressure in order to create many cracks in the shale formation which will release the crude oil that has been trapped there for millions of years. This process has caused debate in some areas of the country about the safety of the ground water these wells drill through in order to reach the depth of the oil rich shale. One of the newest of these shale formations is known as the Eagle Ford Shale, located in south Texas. The recoverable oil potential for Eagle Ford shale is around 4.7 billion barrels if only 3% of the oil is recovered from the shale formation and 30% of the oil is usually recovered from a well. Every 1% extraction gained from improved extraction techniques will yield another 1.6 billion barrels of oil (Badiali, 2010). One of the other big shale plays recently discovered is located in Montana and North Dakota. It stretches into Canada and is called the Bakken formation. The United States Geological Survey (USGS) estimated the Bakken formation to hold 3.0 to 4.3 billion barrels of technically recoverable oil using today’s technology (USGS, 2008). Much of the drilling activity on the United States portion of the Bakken formation lies beneath the Blackfeet Indian Reservation that makes getting actual results of drilling activities difficult (Brown, 2011).
(83 166 kJ / mol) for the strain rate changing at a set strain of 0.15 is in a similar range, the rate-limiting process is likely associated with dislocation motion. On the other hand, the activationenergy (1733 kJ/mol) at a set strain of 0.05 is apparently much lower than that of the power-law creep and power-law breakdown regimes. The activationenergy for deformation twinning in magnesium is unknown; however, it is interesting to note that the activationenergy in another HCP metal has been reported to be 40 kJ/mol, when the deformation twinning contributes to deformation. 40) This result suggests that the deformation mechanism for strain rate change at a set strain of 0.05 competes with the deformation twinning. The imposed strain of MgY alloys affects the deformation mechanisms, and these behaviors are found to consist with the deformed microstructural observations, as shown in Figs. 3 5.
synthesized nickel ferrite powder and the reduced products were identiﬁed and characterized by X-ray phase analysis technique (XRD, High power X-ray Diﬀractometer System, Rigaku D/MAX-2500/PC), High Resolution Field Emission scanning electron microscope (FE-SEM, Hitachi S4800), energy dispersive X-ray spectrometry (EDX-Hitachi S4800), optical microscope (Olympus PMG3) and transmission electron microscope (TEM-JEOL-3010).
atures. It was found that at higher reduction temperatures (Fig. 4(b), the only detected phases were the Fe-Ni-Co alloy which reﬂected that the mixed oxides were reduced com- pletely with the formation of ferro-alloy. While at lower temperature, (Fig. 4(a) magnetite traces were observed to reﬂect the incomplete reduction. Also it was observed that the peaks of the synthesized ferro alloy are strong and sharp
Although the Solvent Effect on the Rate and Mechanism of the various type of reaction has been reported.  but very little attention has paid towards the study of the Solvent Effect on the Thermodynamic Activation Parameter and the solvant-solute interaction, particularly for an ion-dipolar reaction. In order to highlight the above noted idea, it has been proposed to make the kinetic study of the solvent effect on the alkali catalysed hydrolysis of Ethyl Acetate has not been paid even a little attention so far.
different a-C:H:Si:O samples in three environments: dry nitrogen, dry air, and humid air. The scaling of friction and wear with load was also investigated. Characterization of the wear tracks through atomic force microscopy (AFM) was used to quantify wear rates and observe nanoscale surface modification that occurs during sliding. The thermal stability of a-C:H:Si:O was investigated through annealing experiments and compared to undoped a-C:H. Raman spectroscopy was used to characterize the structural changes and thermal degradation pathways in a-C:H:Si:O. Additionally, heated AFM probes, which allow for rapid heating and cooling of a nanoscale contact area, were used to probe the thermal stability at time and length scales relevant to applications such as HARM disk drives. Fi- nally, reactive MD simulations using the ReaxFF potential were performed on a-C:H and a-C:H:Si:O in order to understand the atomistic origins of this enhanced thermal stability. The effect of silicon content was also investigated. The simulations provided physical insight into the effect of silicon doping on thermal stability. The activationenergy for rehybridiza- tion was also modeled using the same methods as for the experiments and produced good agreement between the experimental and simulation results.
and P5, respectively. Comparing the position of exothermic peaks on DSC curves at the cooling rate of 5K/min, a significant shift occurred toward a lower temperature and shape of exothermic peaks became sharper with increasing cooling rate. Clearly, crystallization parameters such as nucleation and growth rates are functions of viscosity and degree of undercooling. Therefore, at a higher cooling rate, a higher undercooling was required and a lower crystallization temperature was caused.
linear regression for the pyridine system was conducted for only two plots under 100°C because the first-order rate equation did not successfully adjust to the data above 120°C. The activation energies estimated from the slopes of the regression lines were 120, 135, and 110 kJ/mol for the uncatalyzed, xylene, and pyridine systems, respectively. The order of activationenergy among reaction systems was the reverse that of the reaction rate. This is probably due to the fact that the shortage of reagent supplied to the reaction Fig. 4. Profiles of the reaction of wood meal in the acetic anhydride/ pyridine mixture at 60°C (a), 80°C (b), 100°C (c), and 120°C (d)