2.2. Analyses of DSC curves and demonstration of thermal characterization of insect waxes
There were 1 to 3 heat absorbing peaks or heat releasing peaks clearly seen in the melting or
crystallizing curves of DSC diagrams according to different samples. It was usually symbolized that
different peak with different chemical composition, so it was inferred from the curves that insect waxes
were not single chemicals. For its high sensitiveness, a slight change of heat could be measured by DSC,
thus the little content of chemical constituent of insect waxes was also showed in the diagram and DSC
was able to be used as the identification on wax purity and mixture test. For instance, beeswax showed in
Fig. 4 has at least two composed chemicals, between which was one in lower content with small melting
peak at 40 to 60◦
C, and another in higher content with an orderly significant peak at 60 to 70◦
C. It was
known with wax composition that the change of slope in the chart during 40 to 60◦
C was due to heat
absorbing from free acids and hydrocarbons, and the sharp absorbing peak was lead by fatty acid esters
which were predominant of beeswax at the content of nearly 72%. Although DSC was not a direct way
for chemical composition and structure identification, it provided thermal properties information of insect
wax that related to the state change of substances. It was showed in Table 1 of insect waxes and paraffin/
canauba wax on their main components and number of DSC melting peaks.