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:
-Heat release rates
-Heat of desired reactions and decompositions
-Heat capacities and heat transfer capacities
It took the specialists of calorimetry a long time to recognize and to accept the operational needs, namely:
-Working under controlled temperature conditions (constant temperature, temperature ramps)
-Adding components during runs (continuously or in portions)
-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.
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.
Authors:XiuYan Wang, JieMin Liu, QiShan Yang, Jian Du, FengE Wang, and Wu Tao
be confirmed by studying the decomposition reactionkinetics, and it would be helpful to increase the reaction rate and optimize the process conditions. Dynamic thermal analysis was widely used in investigating reactionkinetics when the changes in
Authors:Jintao Wan, Hong Fan, Bo-Geng Li, Cun-Jin Xu, and Zhi-Yang Bu
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 reactionkinetics of bisphenol A epoxy
Authors:Sebastian Kolmeder, Alexander Lion, Ralf Landgraf, and Jörn Ihlemann
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 reactionkinetics, the specific heat and
Authors:Yong Han, Peng Yang, Jun Li, Cong Qiao, and Tian Li
decreases with increasing solvent polarity.
Moreover, the reactionkinetics 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
Authors:Xiaoli Kang, Jianbo Zhang, Qiang Zhang, Kai Du, and Yongjian Tang
–DSC measurement, aiming at obtaining some information on characteristic temperatures of ignition and afterburning processes. Reactionkinetics of these two processes was also studied by Kissinger method based on DSC data.
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.