*3.1.1 Expanded polystyrene (EPS)*

The polystyrene sample was shredded before being analyzed (**Figure 10**). Two thermal ramps were employed for the TGA/FTIR analysis, the first at a rising temperature of 20°C/min in an inert atmosphere followed by an isotherm in an oxygen atmosphere. The thermogram shows a single weight loss of 99.8 wt % related to the organic part of the polymer and a final residue equal to 0.2% attributed to inorganic impurities present (**Figure 11**).

The FT-IR spectrum of the gas released during the degradation of the polymeric component is reported in **Figure 12**. The spectrum of the gas released at a

**Figure 10.** *EPS sample before (left) and after (right) shredding for TGA analysis.*

**Figure 11.** *TGA analysis of EPS.*

*Microwave-Assisted Pyrolysis Process: From a Laboratory Scale to an Industrial Plant DOI: http://dx.doi.org/10.5772/intechopen.104925*

**Figure 12.** *FT-IR spectrum of the gases released during the TGA analysis of EPS.*

temperature of 480°C shows the typical signals of hydrocarbons due to the degradation products of polystyrene. The degradation occurred by both end chains and random cleavage and gave only aromatic compounds such as styrene monomer and oligomers, benzene, and toluene. The spectrum shows the typical frequencies of aromatic compounds, such as the stretching of the C-H bond at 3000 cm−1, the stretching of the aromatic double bond at 1600–1450 cm−1, and the signals between 900 and 700 cm−1 of the aromatic C-C backbone.

The sample was also subjected to DSC analysis, using three thermal ramps in the temperature range from −10 to 200° C, alternating heating–cooling–heating, in an inert atmosphere. The DSC analysis (**Figure 13**) shows the presence of a peak at about

**Figure 13.** *DSC analysis of EPS.*

60°C, which almost completely disappears in the second heating, probably due to the memory effect or to the presence of traces of volatile compounds in the sample, not visible in the TGA analysis. Furthermore, the sample shows a temperature glass transition at about 94°C, which agrees with the classical Tg of polystyrene. The TGA and DSC analyses show that the sample is essentially polystyrene with probable traces of volatile substances and a small percentage of inorganic impurities.
