## 2 Materials and Methods
### Experimental Methodologies  
The chemical structure of neat PCMs was investigated through Fourier-transform infrared (FTIR) spectroscopy, using a Spectrum One Perkin-Elmer spectrometer (Perkin-Elmer, Shelton, CT, USA) operating in attenuated total reflectance (ATR) mode. The spectra were obtained by averaging 4 scans in the wavenumber range of 4000-640 cm\({}^{-1}\). The ability of the samples to retain the PCM was investigated through leaking tests, which quantifies the PCM loss above its melting temperature. Disks of diameter 20 mm, thickness 1 mm, and masses 1 g were placed into an oven at 60 \({}^{\circ}\)C on filter paper for 3 h, and the masses were monitored hour by hour. Fracture surfaces of compacted panels were observed by scanning electron microscopy (SEM) by using the secondary electron signal of a Zeiss Supra 40 field emission scanning electron microscope (Carl Zeiss, Oberkochen, Germany), which operates at 10\({}^{-6}\) Torr vacuum and an acceleration voltage of 2.5 kV. The surfaces were covered by a thin layer of Pt-Pd before the observations. Thermogravitetric analysis (TGA) was performed using a Mettler TG50 thermbalance (Mettler-Toledo, Greifensee, Switzerland), heating at 10 \({}^{\circ}\)C/min, from 30 \({}^{\circ}\)C to \begin{table}
\begin{tabular}{l c c c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & \multicolumn{2}{c}{**RT35**} & \multicolumn{2}{c}{**RT44**} & \multicolumn{2}{c}{**MPA**} & \multicolumn{2}{c}{**EG**} \\  & **[phr]** & **[wt.\%]** & **[phr]** & **[wt.\%]** & **[phr]** & **[wt.\%]** & **[phr]** & **[wt.\%]** \\ \hline RT35/EG14 & 100 & 87.7 & - & - & - & - & 14 & 12.3 \\ RT44/EG14 & - & - & 100 & 87.7 & - & - & 14 & 12.3 \\ MPA/EG14 & - & - & - & - & 100 & 87.7 & 14 & 12.3 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Sample coding and compositions. Figure 1: Schematic representation of material production through vacuum impregnation and cold compaction. 700 \({}^{\circ}\)C and fluxing 100 mL/min of nitrogen gas. Samples of mass 10 g were analyzed in an alumina crucible. The parameters determined to compare the curves of the different samples were the temperature associated with a mass loss of 5 wt.% (\(T_{5\%}\)), the temperature of the maximum degradation rate (\(T_{\text{peak}}\)), and the residual mass at 700 \({}^{\circ}\)C (\(m_{700}\)). Differential scanning calorimetry (DSC) of neat PCMs and composite samples was performed using a Mettler DSC5+ calorimeter (Mettler-Toledo, Greifensee, Switzerland). The thermal cycles were composed of heating/cooling/heating in the range 25 \({}^{\circ}\)C to 55 \({}^{\circ}\)C in 40 \(\mu\)L aluminum crucibles. The scans were conducted under a nitrogen flow of 100 cm\({}^{3}\)/min at a rate of 1 \({}^{\circ}\)C/min to increase the precision in the determination of the phase transition temperatures [35; 39]. From the thermograms, the characteristic temperatures of the samples were obtained, in particular, the melting temperatures during the first and the second heating scan (\(T_{m1}\) and \(T_{m2}\)) and the crystallization temperature (\(T_{c}\)) in cooling. The specific melting and crystallization enthalpy values (\(\Delta H_{m1}\), \(\Delta H_{c}\), and \(\Delta H_{m2}\)) were additionally determined. The effective PCM content (\(PCM_{m2}^{eff}\)) of the impregnated EG samples was determined in the second heating scan according to Equation (1), and Equation (2) gave the calculation for the efficiency of melting during the second melting scan (\(\eta_{m2}\)). \[PCM_{m2}^{eff}=\frac{\Delta H_{m2}}{\Delta H_{m2,PCM}}\cdot 100 \tag{1}\]  
\[\eta_{m2}=\frac{\Delta H_{m2}}{\Delta H_{m2,PCM}}\cdot W_{PCM}\cdot 100 \tag{2}\]  
where \(\Delta H_{m2\cdot PCM}\) is the specific enthalpy of the neat PCM in the second heating scan and \(W_{PCM}\) is the weight fraction of the PCM. The specific heat capacity at constant pressure (\(c_{p}\)) was determined in the solid state for comparison with a sapphire reference according to the ASTM E1269-11 standard [40].