## 3 Results and Discussion
### Thermal Behavior
#### 3.3.2 Combustion  
The characteristics obtained from the thermal analysis were used to compare the reactivity and combustibility of corn residues. The combustion profiles of the wastes can be seen in Figure 5, where the weight loss due to the increase in temperature can be observed. The main combustion parameters for the different samples are included in Table 4.  
Figure 5: (**a**) TG combustion and (**b**) DTG combustion. According to the results obtained from TG tests, and those inferred from Figure 5, three different areas or stages were observed during combustion of these residues. The first stage was related to moisture loss, from room temperature to the temperature at which 5% weight loss took place [41], ranging between 135.0 \({}^{\circ}\)C for Ma1 and 183.1 \({}^{\circ}\)C for Ma4, according to Table 4. At higher temperatures, a faster stage started with the combustion of volatile compounds, observing a temperature peak between 278.6 and 286.3 \({}^{\circ}\)C, depending on the sample (see Table 4), due to the thermal decomposition of cellulose and hemicellulose, up to the final temperature of this stage, where a change in the slope of the TG curve took place, ranging from 320.6 to 335.5 \({}^{\circ}\)C, depending on the sample. The third stage corresponded to lignin decomposition and char combustion, finishing at the burning temperature, ranging from 485.8 to 511.4 \({}^{\circ}\)C. Lastly, a final stage took place up to 900 \({}^{\circ}\)C, the temperature at which the test finished. With regard to the ignition temperature and taking into account that it is the temperature at which the sample starts burning, the lower this value is, the better combustibility values the waste will have, obtaining similar values for the four samples, varying from 264.6 \({}^{\circ}\)C for Ma3 to 266.6 \({}^{\circ}\)C for Ma1 and Ma4 wastes. Comparing this value with other kinds of biomass such as woody eucalyptus biomass (with an ignition temperature of 295.5 \({}^{\circ}\)C) [28], it can be considered that the combustibility conditions are suitable, obtaining values that are very similar to other herbaceous wastes such as wheat straw (262 \({}^{\circ}\)C) [36] or tobacco stem (250 \({}^{\circ}\)C) [41]. This is due to the fact that herbaceous wastes, as in the case of corn, cellulose and hemicellulose content, are higher than in the case of woody biomass (richer in lignin), and consequently a lower temperature for volatilization is required. In Table 4 the values of the combustion indexes are shown. With regard to the \(D_{i}\) index, the higher it is, the easier it is for combustion to take place, obtaining higher values for Ma3 and Ma4 (274.18 and 252.99%/min\({}^{3}\)\(\times\)\(10^{-3}\), respectively), than in the case of Ma1 and Ma2 samples (with values of 228.12 and 241.81%/min\({}^{3}\)\(\times\)\(10^{-3}\), respectively). In addition, comparing Ma1 and Ma2 samples, a better value of this index was observed for the latter, which means that the leaves included in corncob waste facilitate combustion. The \(S\) index is useful to determine the ignition behavior. The larger the value of the \(S\) index, the higher the combustion activity. As in the case of \(D_{i}\), higher values were observed for M3 and M4 samples (33.92%/\({}^{\circ}\)C\({}^{3}\)\(\times\)\(10^{-7}\) and 30.55%/\({}^{\circ}\)C\({}^{3}\)\(\times\)\(10^{-7}\) respectively), than for Ma1 and Ma2 (26.62%/\({}^{\circ}\)C\({}^{3}\)\(\times\)\(10^{-7}\) and 28.01%/\({}^{\circ}\)C\({}^{3}\)\(\times\)\(10^{-7}\), respectively). Furthermore, comparing Ma1 and Ma2 samples, a better value for this index was observed for Ma2, so it can be concluded that the leaves mixed with the corncob waste improved the activity during combustion. [PERSON] et al. [42] consider good general combustion performance