Thermogravimetric analysis was used as a tool to determine the
relative composition. The thermogravimetric and derivative DTG
curve of Mater-Bi are shown in Fig. 4. The thermal degradation
of the polymer matrix appeared to be cumulative phenomena of
thermal degradation of its three constituents (PBAT, Starch and
additives). In fact, derivative curve shows three peaks, corresponding
to the three steps in the gravimetric curve. The first peak was
attributed to starch degradation (Tmax = 302 C) [9,35]. The second
peak at 357 C was attributed to the additives (like compatibilizing
agent) usually present in Mater-Bi formulations [35,36]. The third
peak was ascribed to PBAT (Tmax = 404 C) by comparing with the
value reported for the pure polymer determined in the same condition
[32]. The area under each peak in the derivative curve corresponds
to the weight loss of each constituent. However, the
overlap of peaks is the main difficulty for quantitative analysis in
TG-DTG. In this article, a deconvolution method was used for
splitting the peaks and evaluating the relative composition of
Mater-Bi. The content of each component is about 70, 20 and
10 wt% for PBAT, starch and additives, respectively.