Some Basics En Route to Isoconversional Methodology - Isoconversional Kinetics of Thermally Stimulated Processes - page 19

1.3 Obtaining Computation-Worthy Data

…and many a good experiment, born of good sense, and
destined to succeed, fails, only because it is offensively sudden.
Ralph Waldo Emerson, The Conduct of Life

Before investing the time and effort in performing kinetic computations, one should
invest both in obtaining computation-worthy experimental data. Neither conditions
of kinetic runs should be selected arbitrarily nor should the sample shape and size
be chosen randomly. The actual measurements should be preceded by exploratory
runs, whose purpose is to reveal the effects of the sample and conditions on the
kinetic data as well as repeatability of the measurements. The idea is to arrange
the sample and conditions so that small changes in them have little or no effect on
the kinetic data. Since it is rarely possible to obtain kinetic data that are entirely
independent of the conditions and sample, one has to make sure that throughout
the whole series of measurements the conditions and sample are well defined and
controlled and that their effects on the kinetics are known. Only in this case one can
obtain computation-worthy data, i.e., the data that are adequate to the actual kinetics
of a process under study.
Although the aforementioned general approach to obtaining computation-worthy
data may seem simple, concrete ways of accomplishing this goal depend on the type
of a process studied. For practical advice on how to collect adequate kinetic data for
a variety of processes, one is recommended to get acquainted with the recommenda-
tions [ 42 ] of the ICTAC Kinetics Committee. Here, we discuss briefly some basic
rules that must be kept in mind when designing kinetic experiments.
There are two constituents of kinetics measurements that control the adequacy of
kinetic data to the process kinetics: sample and instrument. This is obvious from the
procedure of data production schematically shown in Fig. 1.14 . Because a process
is necessarily confined to the sample, the sample parameters unavoidably affect the
process conditions. At the same time, the instrument controls a set of conditions the
sample is exposed to. The adequacy of kinetic data is accomplished only when both
sample and instrument defined conditions are controlled properly. The instrument-
defined conditions include the temperature, the rate of temperature change (i.e., the

Fig. 1.14 The process of
data production. The sample,
conditions, and instrument
unavoidably affect the
data and may distort their
adequacy to the process.
(Reproduced from Vyazovkin
et al. [ 42 ] with permission of
Elsevier)