3.2.2. Thermal stability
The thermal stability of selected films is shown in Fig. 6. Weight loss was associated with three main stages for both films, which presented similar behaviors. The experiment was undertaken from room temperature (∼30◦C) to 600◦C. The first stage was up to 150◦C, mostly related to the continuous loss of free water, 13.10% for the sample Test 3 and 10.00% for the Test 10. The second stage (150–200◦C) was mainly characterized by the loss of glycerol, structurally bound water and protein fractions of smaller size, as also reported by Nagarajan et al. (2013) in films made with gelatin from splendid squid skin. The Test 3 showed 7.43% of weight loss in this range of temperature and Test 10 sample showed 5.05%, which represents that Test 10 was slightly more thermally stable.The greater weight loss of Test 3 can be ascribed to the presence oflow molecular fraction of other compounds, such as the bioactive coumpounds contained in the carrot residue fiber. Protein fractions of larger size or those highly associated were lost in the third stage, in temperatures ranging from 200◦C to 450◦C. From 250◦C, the variation of weight loss of Test 10 was slightly greater than Test 3 and this behavior was extended to the end of the experiment, where at 600◦C, Test 3 showed ∼17% residual mass, while Test 10 had ∼14%. This result may be due to the presence of the fibers and their interactions with the components of the biopolymer matrix via covalent and non-covalent bonding, which caused an increasing in the carbon residue content, considering that the analysis was made under inert atmosphere and the combustion was not complete (Oliveira et al., 2015). Therefore, it was possible to observe that the addition of CF slightly affected the thermal stability of the resulting CG–CF composite film, but the TGA curves indicated that the two studied films had similar thermograms and were thermally stable until near 200◦C.
3.2.2. ความร้อนเสถียรThe thermal stability of selected films is shown in Fig. 6. Weight loss was associated with three main stages for both films, which presented similar behaviors. The experiment was undertaken from room temperature (∼30◦C) to 600◦C. The first stage was up to 150◦C, mostly related to the continuous loss of free water, 13.10% for the sample Test 3 and 10.00% for the Test 10. The second stage (150–200◦C) was mainly characterized by the loss of glycerol, structurally bound water and protein fractions of smaller size, as also reported by Nagarajan et al. (2013) in films made with gelatin from splendid squid skin. The Test 3 showed 7.43% of weight loss in this range of temperature and Test 10 sample showed 5.05%, which represents that Test 10 was slightly more thermally stable.The greater weight loss of Test 3 can be ascribed to the presence oflow molecular fraction of other compounds, such as the bioactive coumpounds contained in the carrot residue fiber. Protein fractions of larger size or those highly associated were lost in the third stage, in temperatures ranging from 200◦C to 450◦C. From 250◦C, the variation of weight loss of Test 10 was slightly greater than Test 3 and this behavior was extended to the end of the experiment, where at 600◦C, Test 3 showed ∼17% residual mass, while Test 10 had ∼14%. This result may be due to the presence of the fibers and their interactions with the components of the biopolymer matrix via covalent and non-covalent bonding, which caused an increasing in the carbon residue content, considering that the analysis was made under inert atmosphere and the combustion was not complete (Oliveira et al., 2015). Therefore, it was possible to observe that the addition of CF slightly affected the thermal stability of the resulting CG–CF composite film, but the TGA curves indicated that the two studied films had similar thermograms and were thermally stable until near 200◦C.
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