This paper is a review of some of the controversial kinetic aspects of thermal analysis, starting from the ‘šesták questions’
posed in 1979 and looking at developments in some areas since that time. Aspects considered include: temperature programmes
and variations, models and mechanisms, kinetic parameters, distinguishability and extent of fit of kinetic models, complementary
evidence for kinetic models, the Arrhenius equation and the compensation effect. The value of the ideas of non-isothermal
kinetics in chemical education is emphasized.
Some applications of thermal analysis (TA) and temperature profile analysis (TPA) to the study of a variety of binary pyrotechnic
systems are described. Factors that effect the combustion of such fuel/oxidant mixtures are discussed. Trends in burning behaviour
and the experimental limitations of the techniques available are identified.
Professor Vladimir V. Boldyrev has made numerous important contributions to a wide range of chemical topics, not only limited
to studies of the decompositions of solids. Of particular value has been his emphasis on exploring, in detail, the chemical
steps participating in the thermal reactions of solids by carefully designed experiments that rely on more observational evidence
than the run-of-the-mill collection of overall kinetic data. Some of these major contributions to both the theory and the
uses of solid-state reactions are identified here and discussed in relation to his illuminating and fundamental mechanistic
studies of the thermal decompositions of silver oxalate, ammonium perchlorate, potassium permanganate and the dehydration
of copper sulfate pentahydrate.
Authors:M. Brown, M. Tribelhorn, and M. Blenkinsop
Thermal analysis is routinely used to characterize pyrotechnic fuels, oxidants and fuel/oxidant mixtures . Thermomagnetometry
(TM) can provide additional information if the magnetic properties of the materials change during reaction. TG, TM and DTA
results for the iron/potassium permanganate, iron/barium peroxide, and iron/strontium peroxide systems as loose powders or
pressed pellets indicate predominantly solid-gas mechanisms for reactions in these systems.
The thermal behaviour of the aminosalicylic acids is compared with the behaviour of their 1:1 molar ratio physical and kneaded
mixtures with each of three different cyclodextrins (b-, hydroxypropyl-b-, and g-cyclodextrin), using differential scanning
calorimetry and thermogravimetry coupled with evolved gas analysis by Fourier transform infrared spectroscopy. X-ray powder
diffraction and infrared spectroscopy provided complementary information. Comparison of the effects of the different cyclodextrins
on the behaviour of the individual aminosalicylic acid isomers shows that hydroxypropyl-b-cyclodextrin has the greatest interaction
with 3-aminosalicylic acid and 5-aminosalicylic acid, followed by g-cyclodextrin, while b-cyclodextrin generally shows the
least interaction. For 4-aminosalicylic acid, the effect of g-cyclodextrin seems to be more marked than for 3-aminosalicylic
acid and 5-aminosalicylic acid.
Nifedipine complexes with β-cyclodextrin (β-CD), γ-cyclodextrin (γ-CD), 2-hydroxypropyl-β-cyclodextrin (2HP-β-CD), randomly
methylated-β-cyclodextrin (RM-β-CD) and heptakis(2,6-O-dimethyl)-β-cyclodextrin (DM-β-CD) have been prepared by both kneading and heating methods and their behaviour studied by
differential scanning calorimetry (DSC), diffuse reflectance mid-infrared spectroscopy (FTIR) and X-ray diffractometry (XRD).
DSC revealed the nifedipine melting endotherm with onset at approximately 171°C for the kneaded mixtures with β-CD, γ-CD and
2HP-β-CD, thus confirming the presence of nifedipine in the crystalline state, while some decrease in crystallinity was observed
in the DM-β-CD kneaded mixture. With RM-β-CD, however, broadening and shifting of the nifedipine endotherm and reduction in
its intensity suggested that the kneading could have produced an amorphous inclusion complex. These differing extents of interaction
of nifedipine with the cyclodextrins were confirmed by FTIR and XRD studies.