## 3 Results
### Structural Characterization and Material Properties of the Nanocomposites  
The infrared spectra of the nanocomposites at three different concentrations of nanofillers (1 wt%, 3 wt%, and 5 wt%), as well as the neat PS, are shown in Figure 5. The spectra of nanocomposites have all those bands that exist at PS sample. The observation of peaks corresponding to the CNWs is difficult, due to the similar nature of the materials and the low addition rate of the nanofillers to the final nanocomposites. The absorbance bands are in a wide area of the spectra. The first major band at 3025 cm\({}^{-1}\) corresponds to the stretching vibrations of aromatic C-H bonds, while the second major band at 2921 cm\({}^{-1}\) is from the same kind of vibrations of C-H on carbon chains. The next three major bands at 1600, 1492 and 1451 cm\({}^{-1}\) are attributed to aromatic C-H bond stretching vibrations, as well as the major peaks that are located at 1260, 1017, 796, 749 and 695 cm\({}^{-1}\), which indicate aromatic C-H deformation vibration [32]. Figure 6 shows the DTA (a) and TG (b) curves for the nanocomposites PS-CNWs at two different analogies with 1 wt% and 5 wt% CNNs. On both samples, endothermic peaks appear at 308 \({}^{\circ}\)C, 377 \({}^{\circ}\)C and 400 \({}^{\circ}\)C or 320 \({}^{\circ}\)C and 365 \({}^{\circ}\)C, respectively, as well as an exothermic peak at 515 \({}^{\circ}\)C. Contrarily, the DTA curve of PS inhibits a strong intensity exothermic peak at 408 \({}^{\circ}\)C. This peak is correlated to the decomposition of the polymeric structure through depolymerization of the form:  
This decomposition is catalyzed by the Pt crucible and greatly affects the DTA signal [33; 34; 35]. The differentiation observed at the nanocomposites curves can be assigned to the existence of nanowires  
Figure 5: Fourier-transform infrared (FT-IR) spectra of samples: neat polystyrene (PS), PS-CNWs-1%, PS-CNWs-3% and PS-CNWs-5% samples. that are surfaced modified by ODA molecules. It is well known that the decomposition of amine groups occurs at temperatures below 400 \({}^{\circ}\)C and over more than one step. Therefore, given the fact that the graphitic structure of CNWs is not affected at temperatures below 350 \({}^{\circ}\)C, the endothermic peaks at 308 \({}^{\circ}\)C and 320 \({}^{\circ}\)C at the nanocomposite spectra are attributed to the amine groups decomposition, catalyzing the decomposition of PS to lower temperatures (365 \({}^{\circ}\)C and 377 \({}^{\circ}\)C). The exothermic peaks near 515 \({}^{\circ}\)C are indicative of the combustion of nanowires, as well as the remaining organic part of the nanocomposite matrix. From the TGA curves, the nanocomposites are less thermally stable than the neat-PS. Specifically, the sample with 5 wt% CNWs is by 10 \({}^{\circ}\)C more thermal stable than the 1 wt% CNWs nanocomposite. Nevertheless, it is less thermally stable than the neat polymeric matrix by 10 \({}^{\circ}\)C. It is cited that for nanocomposite materials with carbon as nanofiller in PS matrix, the final product becomes more thermally stable than the pristine polymer with regard to the concentrations of nano-additive above 10 wt%. Raman spectra of the pristine PS, as well as for the three different nanocomposites, are shown in Figure 7. The spectra of all samples exhibit the two intense peaks at 1601 and 1352 cm\({}^{-1}\), which are the characteristic G and D-bands [36] mentioned before. Once again, the graphitization of the samples is unaffected while they are formed to nanocomposites. Specifically, the value of the I\({}_{\text{D}}\)/I\({}_{\text{G}}\) ratio is 0.80, 0.82, and 0.87 for the samples with 1 wt%, 3 wt% and 5 wt% CNWs, respectively. This value is considered almost equal. In all nanocomposites, the characteristic bands of the PS are dominant. Those peaks are mainly at 3059 and 2908 cm\({}^{-1}\). Both are attributed to the C-H bonds' vibrations.