66
8.3 Investigations with Differential Scanning Calorimetry
The method of materials structure characterization
which is complementary to
PALS but more popular and conventional is Differential Scanning Calorimetry (DSC). It is
based on the influence of the temperature on physical properties of the sample. During the
measurement, the differences of temperatures are measured
between the tested and the
reference sample, in which no structural transitions occur.
Structural changes in the
examined sample are correlated with changes of heat capacity. Relying on this, exo - and
endothermic processes in the sample can be identified.
DSC measurements of polyvinyltoluene - based
J-PET scintillator and pure
polyvinyltoluene were carried out. Registered thermograms
are presented in
Figs. 33 and 34.
150
200
250
300
350
400
-6
-4
-2
0
2
4
6
Heat
flo
w (end
o u
p) [mW]
Temperature [K]
-150
-100
-50
0
50
100
150
Temperature [
C]
Figure 33 Thermogram of J-PET scintillator containing 0.05 ‰ of novel WLS. Red line denotes heating, blue one
cooling of the sample.