## 3 Results and Discussion
### Chemical Characterization by FT-IR Analysis  
Chemical characterization of gamma-irradiated plastic particles was analyzed by using FT-IR microscope, in a [PERSON] model VERTEX 80v coupled to HYPERION 2000 machine. FT-IR analysis was performed to analyze the chemical properties of the plastic aggregates as a result of the effects of gamma irradiation. Referring to the existing literature [45], the absorption bands for the FT-IR spectra are summarized in Table 6 and were used to analyze the properties of each plastic. Figures 14-18 show a comparison of FT-IR spectra changes according to the gamma irradiation dose for each plastic type. The symbols assigned to the absorption bands used for identification by plastic types in Table 6 are matched and displayed in Figures 14-18. The absorption band peak in the spectra for each plastic type was found to be mostly similar to the vibrational characteristics of the absorption band peak of each plastic material described in the existing literature. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Plastic Type** & **Molecular Structure** & **Absorption Bands (cm\({}^{-1}\)) for Identification Indicating the Peak Position and Mode Assignments** \\ \hline Polypropylene (PP) & & 2950 (a): C–H stretching 2915 (b): C–H stretching 2838 (c): C–H stretching 1455 (d): CH\({}_{2}\) bending 1377 (e): CH\({}_{3}\) bending 1166 (f): CH bending, CH\({}_{3}\) rocking, C–C stretching 997 (g): CH\({}_{3}\) rocking, CH\({}_{3}\) bending, CH bending 972 (h): CH\({}_{3}\) rocking, C–C stretching 840 (i): CH\({}_{2}\) rocking, C–C stretching, C–CH stretching 808 (j): CH\({}_{2}\) rocking, C–C stretching, C–C stretching \\ \hline Polyethylene (PE) & \(\left[\begin{array}{c}H\\ \end{array}\right]\) & 2915 (a): C–H stretching 2845 (b): C–H stretching 1472 (c): CH\({}_{2}\) bending 1462 (d): CH\({}_{2}\) bending 730 (e): CH\({}_{2}\) rocking 717 (f): CH\({}_{2}\) rocking \\ \hline Polycarbonate (PC) & \(\left[\begin{array}{c}\text{CH}_{3}\\ \end{array}\right]\) & 2966 (a): C–H stretching 1768 (b): C=O stretching 1503 (c): Aromatic ring stretching 1409 (d): Aromatic ring stretching 1364 (e): CH\({}_{3}\) bending 1186 (f): C–O stretching 1158 (g): C–O stretching 1013 (h): Aromatic CH in-plane bending 828 (i): Aromatic CH out-of-plane bending \\ \hline Acrylonitrile & 2922 (a): C–H stretching 1602 (b): Aromatic ring stretching 1494 (c): Aromatic ring stretching 1452 (d): CH\({}_{2}\) bending 966 (e): C–H bending 759 (f): Aromatic CH out-of-plane bending =CH bending 698 (g): Aromatic CH out-of-plane bending \\ \hline Polyethylene (PET) & \(\left[\begin{array}{c}\text{CH}_{3}\\ \end{array}\right]\) & 1713 (a): C=O stretching 1241 (b): C–O stretching 1094 (c): C–O stretching 720 (d): Aromatic CH out-of-plane bending \\ \hline \hline \end{tabular}
\end{table} 
Table 6: List of important vibration modes and mode assignments for the FT-IR spectra [45]. As a result of the FT-IR analysis of the PP aggregate, from Figure 14, in the FT-IR spectrum of neat PP, the peaks observed near 1166 and 977 cm\({}^{-1}\) confirm that the PP used in the present case isotactic. It is observed that the intensity of these peaks continuously decreases with the increase in gamma irradiation dose, and this indicates that these bonds are the result of chain scission by gamma radiation. Furthermore, new characteristic bands at 1650 cm\({}^{-1}\) appear at all the gamma dose levels. These correspond to the carbonyl C=O groups, and the appearance of the C=O group indicates oxidation. This is because the C-H and C-C bonds of PP are the result of scission and consequently the formation of free radicals and ionized species. The reaction of free radicals with oxygen does not allow the polymer chains to crosslink, which leads to chain scission predominating over crosslinking in PP. Figure 14: FT-IR spectra of polypropylene (PP) aggregate with different irradiation doses. Figure 15: FT-IR spectra of polyethylene (PE) aggregate with different irradiation doses.