## 3 Results  
### Pyrolysis Test and Char Characterization  
Table 1 summarizes the main results of the pyrolysis tests. T-Const and T-Max are the average temperature and the maximum peak temperature reached during the pyrolysis process, respectively. It can be seen that the loss in mass was slightly greater in the higher temperature test (as was expected). The gas production during the fluxed pyrolysis was not detected because the outlet gas flow was very similar to the CO\({}_{2}\) flow of about 2.1 L/min; a more accurate measurement system would have been needed to detect small flow differences. Table 2 reports the results of the filtration and distillation tests using the tar and particulates sampling method [16]. The non-fluxed pyrolysis tests, despite the temperature difference, did not show substantial differences (slightly less dust but more tar in the lower temperature test); however, there was an important difference in the powders of the fluxed test, which were 10 times higher than their non-fluxed counterparts, a fact probably deriving from the turbulent influence of the fluxed CO\({}_{2}\) on the transport of the powders  
themselves. Fluxed pyrolysis also resulted in higher tar yield. This was in accordance with the literature; in fact, gas sweeping drags the hot vapours and organic compounds out of the pyrolysis zone, stopping secondary reactions such as repolymerisation [28; 29]. The elemental analysis, summarized in Table 3, did not reveal substantial differences between the char obtained from the various tests, but there was a slightly higher carbon and ash content in the higher temperature one. To measure pH and electrical conductivity, 10 mL of char powder was sampled, diluted in a 5:1 ratio in distilled water (50 mL), placed on a stirrer for 1 h and then filtered. The results listed in Table 4 show that, although a more basic pH was possessed by the sample pyrolysed at 640 \({}^{\circ}\)C, this latter had a lower electrical conductivity (which represents the dissolved salts), indicating a lower ionization. It should also be remembered that, for use in the agronomic field, materials must have a pH between 6.5 and 7.5 [25] and an electrical conductivity of less than 2 mS/cm [26]. By measuring the on and off times of the resistors and knowing their operating power, it was possible to measure the specific energy consumption for these particular experimental setups. Figure 3 shows the specific energy spent in heating the cork waste for different types/temperatures of pyrolysis. It does not take into account the relative energy losses of the system. Among all the analysis shown, none of the fluxed pyrolyses at 420 \({}^{\circ}\)C produced a completely carbonized material using the lower amount of energy; for this reason, only chars obtained with this process were used for the following material formulation. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Test** & **T-Const (\({}^{\circ}\)C)** & **T-Max (\({}^{\circ}\)C)** & **Initial Mass (g)** & **Final Mass (g)** & **Mass Loss (\%)** & **Gas Production (L)** \\ \hline
**Pyolysis** & 420 & 517 & 19.44 & 8.31 & 57 & 1.8 \\
**T = 420 \({}^{\circ}\)C** & 415 & 475 & 20.81 & 10.42 & 50 & - \\
**Pyolysis** & 638 & 650 & 18.60 & 6.88 & 63 & 1.5 \\
**T = 640 \({}^{\circ}\)C** & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Temperatures and mass losses from the pyrolysis tests. \begin{table}
\begin{tabular}{l c c c c} \hline \hline
**Material** & **N\%** & **C\%** & **H\%** & **S\%** & **ASH\%** \\ \hline
**Dry c powder** & 0.88 & 63.33 & 8.53 & - & 0.52 \\ Dry cork powder pyrolysed at 420 \({}^{\circ}\)C & 0.76 & 73.95 & 9.95 & - & 0.76 \\ Dry cork powder pyrolysed at 640 \({}^{\circ}\)C & 1.32 & 76.75 & 7.84 & - & 1.71 \\ Dry cork powder pyrolysed at 415 \({}^{\circ}\)C (fluxed)** & 1.27 & 71.11 & 9.09 & - & 1.10 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Elemental analysis results.