The baseline construction and its influence on the measurement of heat with differential scanning calorimeters

Abstract

In DSC's the shape of the interpolated baseline under a peak is determined by a change in the heat capacity of the sample and the heat transfer characteristics between sample and temperature sensor. The interpolated baseline is constructed according to formal criteria, experimentally or analytically on the basis of physico--chemical assumptions on the change of the heat capacity during transition. By the example of the melting of ice this paper shows analytically on the basis of a simple calorimeter model and a synthetic measuring curve, and experimentally, that the uncertainty of the enthalpy determination depends in general on the type of baseline and is in the order of magnitude of the repeatability of the DSC's (•

Determination of activation energy and preexponential factor of thermoset reaction kinetics using differential scanning calorimetry in scanning mode: Influence of baseline shape on different calculation methods

“…), and errors in the interpretation of the DSC thermograms (baseline error). It is known that the baseline of a DSC scan experiment for a thermoset is not a straight line, 11 but it is a complicated process to obtain its real shape: it can be obtained by heat capacity measurements (as explained below) or direct measurement by temperature modulated DSC. 12 Nevertheless, this recent method is still not commonly used and most of the kinetic studies are made with conventional DSC.…”

A study of the α ↔ γ transformation in pure iron: rate variations revealed by means of thermal analysis

“…It has been verified that the time over which the transformation occurs scales linearly with the inverse square root of the heating rate employed for the experiments as expected from consideration of heat resistance models for the DTA instrument [20]. Therefore, the length of the peak is related to the need of either supplying heat to or removing heat from the sample cell.…”

“…Examples of DTA traces for melting and solidification of Au are shown, together with their The difference in temperature, ∆T, between the sample and the reference cell during melting can be expressed as [20] …”

“…Φ the heating rate, and R the heat resistance of the instrument. After melting is complete at t p , ∆T is given by * The equations describing the DTA signal have been reported and thoroughly discussed in [18][19][20]. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 …”

Tuning morphologies of thermoset / thermoplastic blends Part 1: Kinetic modelling of epoxy-amine reactions using amine mixtures

“…DSC signal W obtained for a reactive thermoset sample submitted to a temperature ramp can be divided into two contributions [33]: Assuming that Δ r H is a constant over all the experimental temperature range [34,35], it can be measured by integration of the exothermal peak area. Each experiment provides a set of data including time, temperature, rate of conversion and conversion degree.…”