## 3 Results
During this degradation step the dehydration of neighbouring hydroxyl groups in the glucose ring take place, resulting in the formation of C-C bonds or breakdown of the glucose ring with the further formation of aldehyde end groups [27]. The DTG curve (Figure 6b) shows that the maximum degradation temperature (T\({}_{\text{max}}\)) did not present differences between all the materials with a mean value around 316 \({}^{\circ}\)C (316.6 \(\pm\) 1.8 \({}^{\circ}\)C). Even so, the effect in the mass loss was appreciable in the formulations that contain gum resin and derivatives. This effect can be seen in Figure 6a, at 350 \({}^{\circ}\)C. The TPS reports a mass loss of 20%. In the case of TPS blended with GR, LF and RD reduction in the mass loss of 29%, 29% and 27% were observed, respectively. The incorporation of CM and UG to TPS showed the mass loss of TPS in 23%. GR, LF and RD created interactions and links with TPS matrix, because of the presence of carbonyl and ester groups, which protect the polymeric matrix from thermal degradation [5]. Besides, CM resin produced less effect in the thermal protection because the spatial distribution of its molecules avoids the creation of a lot of links between resin and TPS polymeric matrix. It is important to notice that even when UG resin has carbonyl groups on its structure, the effect in the thermal stability is lower that the LF resin which possesses one more carbonyl group and higher molecular weight. At 335 \({}^{\circ}\)C the final degradation step takes place, where organic residues decompose and turn into ashes. It is seen that all the pine resins protected TPS matrix from thermal degradation, with GR, LF and RD providing the greatest stability in the degradation endset temperature. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Material** & **T\({}_{\text{5\%}}\) (\({}^{\circ}\)C)** & **T\({}_{\text{max}}\) (\({}^{\circ}\)C)** & **T\({}_{\text{95\%}}\) (\({}^{\circ}\)C)** \\ \hline TPS & 109.3 \(\pm\) 2.1 & 317.3 \(\pm\) 1.9 & 564.8 \(\pm\) 2.3 \\ TPS-GR & 138.3 \(\pm\) 1.9 & 318.3 \(\pm\) 1.7 & 624.3 \(\pm\) 2.1 \\ TPS-CM & 132.8 \(\pm\) 2.0 & 315.8 \(\pm\) 1.9 & 553.8 \(\pm\) 1.9 \\ TPS-LF & 133.8 \(\pm\) 1.9 & 316.3 \(\pm\) 1.7 & 576.3 \(\pm\) 2.3 \\ TPS-RD & 126.3 \(\pm\) 1.8 & 316.8 \(\pm\) 2.0 & 632.2 \(\pm\) 1.8 \\ TPS-UG & 121.8 \(\pm\) 2.0 & 315.8 \(\pm\) 1.8 & 570.2 \(\pm\) 2.0 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: TGA thermal parameters degradation onset temperature (T\({}_{\text{5\%}}\)), temperature of maximum degradation rate (T\({}_{\text{max}}\)) and degradation endset temperature (T\({}_{\text{95\%}}\)) for TPS and the TPS-resin blend formulations. Figure 6: **(a)** TGA and **(b)** their derivatives (DTG) curves of neat TPS and TPS-resin blend formulations. The FTIR spectra comparison of neat TPS and TPS-resin blends formulations with 10 wt. % of gum rosin (GR) and rosin derivatives (CM, LF, RD, UG) is presented in Figure 7.  
The FTIR spectrum of neat TPS presents the typical absorption bands corresponding to the functional groups of starch and glycerol. The band corresponding to C-O stretching of C-O-C bond was found at 1010 cm\({}^{-1}\) and 1148 cm\({}^{-1}\) and the C-O stretching of pyranose rings at 926 cm\({}^{-1}\). The bound water band was located at 1648 cm\({}^{-1}\) (8 (O-H)). The O-H groups are found at 3284 cm\({}^{-1}\) and C-H  
Figure 7: Fourier transform infrared spectroscopy (FTIR) spectra with representative peaks of net TPS and its comparison with TPS-resin blend formulations. A zoom in the range between 2000 cm\({}^{-1}\) and 1500 cm\({}^{-1}\) is also shown. stretching is located at 2924 cm\({}^{-1}\)[54; 55; 56; 57]. The representative bands of the glycerol plasticizer were displayed at 2884 cm\({}^{-1}\)(C-H), associated with the hydroxyl groups, as well as at 1416 cm\({}^{-1}\) and at 1148 cm\({}^{-1}\) (C-O stretching), associated with carbon-oxygen (C-O) absorption peaks characteristic of primary and secondary alcohols [19; 54; 56].