## 3 Results and Discussion
They noticed that after pyrolysis the nanocomposite forms a char layer with a multi-layered carbonaceous-silicate structure that builds up on the surface of the material during burning and has the capacity to insulate the material and to slow down the volatile products [44]. According to Figure 3, the best results were achieved when both OMT and FR were used, due to the synergy between them in the process of the char progression. Figure 1: Released heat against time for reABS (recycled acrylonitrile-butadiene-styrene) and reABS with fire retardant (FR) and organic montmorillonite (OMT). Figure 3: Released heat against time for reABS with 2% OMT and different mass percentages of FR. Figure 2: Released heat against time for reABS with 1% OMT (organic montmorillonite) and different mass percentages of FR. Figures 4-6 present the mass loss against time. It is possible to conclude that the reABS is burnt almost completely (98.4% mass loss) after a relatively short time in comparison with reABS with 15% FR which presents a double burning time and an 89.3% mass loss. These results are in line with the outcomes of [PERSON] et al. [1] (i.e., a mass loss of 87.7% when 25% FR is added to pristine ABS). However, the influence of 1%-2% OMT is rather limited. Similar details are shown in Figures 5 and 6, where it can be clearly seen that the addition of FR greatly influences the mass loss reduction. More precisely, the decomposition time increases around 10% and 20% after  
Figure 4: Mass loss against time for reABS with OMT and FR. Figure 5: Mass loss against time for reABS with 1% OMT and different percentages of FR. adding 1% and 2% OMT, respectively, but when FR is added an increase of 200% is achieved in terms of decomposition time and 89.3% of the mass loss. In this case the mass loss is related to the released heat and fire propagation, as [PERSON] et al. [12] revealed in their study of materials with OMT and different fire retardants. Table 5 summarizes the results obtained from the figures for different times (after 100, 200, and 300 s), in order to evaluate the influence of OMT and FR on the reABS polymer. For example, the mass remaining after 300 s burning increases greatly when fire retardant and OMT are added, reaching a maximum mass of 57.35% of the initial weight for ABS + 1% OMT + 20% FR, while all samples with OMT and FR showed good firing behavior. The minimum decrease in the mass loss after 100 s burning was registered for reABS 1% OMT 20% FR (85.49% from initial mass remains after burning), following the same trend as PHRR reduction. As a further observation, even if adding only OMT the mass loss decreases by about 5% and on adding solely FR, 35% is obtained. Combining FR and OMT gave very good results in terms of burning behavior if the data from Table 5 are compared. Since the reduction in PHRR follows the reduction in mass loss rate, this correlation is essential to be noted [43]. Finally, another important parameter derived from the con-calorimeter test is the burning time that reflects the time needed for a specific material to decompose and to generate the volatile materials that sustain the burning process. Figure 7 presents the regression analysis of the experimental results \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Specimen**} & \multicolumn{3}{c}{**Mass after Burning [\%]**} \\ \cline{2-4}  & **100 s** & **200 s** & **300 s** \\ \hline reABS & 55.03 & 4.35 & 0.74 \\ reABS 15\% FR & 76.34 & 55.79 & 35.99 \\ reABS 1% OMT & 63.45 & 15.28 & 4.16 \\ reABS 1\% OMT 15\% FR & 82.39 & 66.29 & 50.45 \\ reABS 15\% OMT 18\% FR & 84.29 & 69.23 & 55.47 \\ reABS 15\% OMT 20\% FR & 85.49 & 71.44 & 57.35 \\ reABS 2\% OMT & 66.41 & 29.71 & 6.3 \\ reABS 2\% OMT 15\% FR & 84.17 & 68.37 & 53.2 \\ reABS 2\% OMT 18\% FR & 84.03 & 69.2 & 54.11 \\ reABS 2\% OMT 20\% FR & 84.33 & 70.13 & 55.95 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Mass loss after different burning times. Figure 6: Mass loss against time for reABS with 2% OMT and different percentages of FR.