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Abstract

Classical thermo-analytical micro methods (DTA, DSC) are still very useful for process work, but medium scale instruments based on heat flow measurement are attaining an increasingly important role in this domain.

As in many areas, development of reaction calorimetry for industrial applications was driven by needs and by available means (technical capabilities).

The needs have been fairly constant over the past decades. There are data needs:

  1. -Reaction rates
  2. -Heat release rates
  3. -Heat of desired reactions and decompositions
  4. -Heat capacities and heat transfer capacities

It took the specialists of calorimetry a long time to recognize and to accept the operational needs, namely:

  1. -Working under controlled temperature conditions (constant temperature, temperature ramps)
  2. -Adding components during runs (continuously or in portions)
  3. -Simulation of industrial mixing conditions

The main driving force for the development of process oriented calorimetric instruments was the evolution of electronic hardware which made the control of heat flow on a (non micro) laboratory scale easy.

The paper gives an overview on the principles of heat flow control and reviews the developments of the fifties and sixties, when the matching of heat flow with heat release by reactions was the goal.

With the advent of fast and powerful laptop computers, the focus has shifted. Now, the deduction of true heat release rates from signals which may be badly distorted, is the goal.

Some recent developments are reviewed and the hope is expressed that calorimetric equipment, inexpensive enough to be affordable for every laboratory engaged in process work, will be available soon.

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Model-free kinetics

Staying free of multiplying entities without necessity

Journal of Thermal Analysis and Calorimetry
Author: S Vyazovkin

Abstract  

The paper presents the model-free kinetic approach in the context of the traditional kinetic description based on the kinetic triplet, A, E, and f(α) or g(α). A physical meaning and interpretability of the triplet are considered. It is argued that the experimental values of f(α) or g(α) and A are unlikely to be interpretable in the respective terms of the reaction mechanism and of the vibrational frequency of the activated complex. The traditional kinetic description needs these values for making kinetic predictions. Interpretations are most readily accomplished for the experimental value of E that generally is a function of the activation energies of the individual steps of a condensed phase process. Model-free kinetic analysis produces a dependence of E on α that is sufficient for accomplishing theoretical interpretations and kinetic predictions. Although model-free description does not need the values of A and f(α) or g(α), the methods of their estimating are discussed.

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be confirmed by studying the decomposition reaction kinetics, and it would be helpful to increase the reaction rate and optimize the process conditions. Dynamic thermal analysis was widely used in investigating reaction kinetics when the changes in

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systems. Herein, we report an original, systematic work on synthesis and characterization of a novel acrylonitrile-modified aliphatic polyamine (PAN4) with a perfect dendritic molecular architecture, and nonisothermal reaction kinetics of bisphenol A epoxy

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model for curing adhesives, originally developed by Lion and Höfer [ 16 ], minor modifications were made to adopt it for the bone cement material. A detailed experimental database of the bone cement, including the reaction kinetics, the specific heat and

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decreases with increasing solvent polarity. Moreover, the reaction kinetics obeys a second-order rate law in toluene, butyl acetate, cyclohexanone and pyridine, but a first-order rate law is valid in NMP and DMF, and there is no distinction for the

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mL aqueous alcoholic solution, temperature 313 ± 1 K Thus, the reaction kinetics can be described by the equation: where r is the disappearance rate of 3-phenoxybenzaldehyde, k is an apparent rate

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–DSC measurement, aiming at obtaining some information on characteristic temperatures of ignition and afterburning processes. Reaction kinetics of these two processes was also studied by Kissinger method based on DSC data. Experimental

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Abstract  

The curing reaction of a thermosetting system is investigated by DSC and temperature modulated DSC (TMDSC). When the material vitrifies during curing, the reaction becomes diffusion controlled. The phase shift signal measured by TMDSC includes direct information on the reaction kinetics. For long periods the phase shift is approximately proportional to the partial temperature derivative of the reaction rate. This signal is very sensitive for changes in the reaction kinetics. In the present paper an approach to determine the diffusion control influence on the reaction kinetics from the measured phase shift is developed. The results are compared with experimental data. Further applications of this method for other reactions are proposed.

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-capacity standard reference material: sapphire ( a -Al 2 O 3 ) from 10 to 2250 K . J Res Natl Bur Stand 87 : 159 – 163 . 13. Kissinger , HE 1957 Reaction kinetics in

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