## 3 Evaluation of Polymeric Materials in Thermal Processes  
The evaluation of pyrolysis and other thermal preparation methods of polymeric materials is critical to ensuring the profitability of a process. Action should be focused on three primary areas in this context: raw material evaluation, process parameters and associated conditions, and product evaluation. A physicochemical property evaluation is important for all thermal processes, including combustion and gasification. Ultimate analysis, proximal analysis, differential thermal analysis, and thermogravimetric analysis all play key roles in this regard [12; 13; 72]. The ash content, volatile matter, and moisture content are all included in the proximate analysis. The concentrations of elements such as carbon, hydrogen, sulphur, and oxygen are included in the final analysis and combined to generate a combustible and incombustible material, the same as traditional fuels. The concentration of these parameters influences energy usability by determining the lower and higher heating values [12; 13; 72]. Thermogravimetric analysis (TGA) is used to evaluate the temperature ranges at which polymeric materials disintegrate. Gas chromatography, on the other hand, is used to investigate volatile products of catalytic and non-catalytic pyrolysis. All of these approaches are carried out automatically, owing to the availability of specialised analysers with great sensitivity and accuracy [12]. BTEX generated from polymeric material pyrolysis yields important compounds such as phenol, chlorobenzene, styrene, maleic anhydride, and phthalate anhydride. Aside from the process parameters, one of the most essential components is the variety of polymeric materials and catalysts  
Figure 5: All aromatics yield as a function of material and catalyst ratio (based on [19]). available. The use of PP during catalytic pyrolysis facilitates the synthesis of long-chain alkenes and alkanes at many stages through isomerization and aromatization, as illustrated in Figure 6.  
As a result of Walden inversion, one isomer is changed into a second at the first stage (isomerization; in a chiral carbon atom with an R or S configuration). Second, cyclization converts the a-cyclic component of the chain into a cyclic component. A new chemical bond was generated [73]. As an example, the authors demonstrated that the product obtained from ABS pyrolysis without a catalyst contained less than 50% of 2-phenylpropene [73], which was utilised instead of styrene to polymerize heat-resistant ABS. This was used as a raw material for organic compounds used as pigments, paints, adhesive agents, and latex. Despite the lack of catalyst applications, ABS with a lower concentration of 2-phenylpropene can be processed as pigments, paint, adhesive agents, and latex, and an additive to plastics. Thermal and Chemical Utilisation of Polymeric Materials and Their Waste and Environmental Impact  
Each technological solution involving the chemical usage of polymer materials and their byproducts results in environmental problems. Chemical substances generated during the thermal degradation of polyolefins have significant carcinogenic and mutagenic potential. As a result, one of the primary challenges is the use of systems that enable the minimisation of negative phenomena such as exhaust gases, dust, and process effluents, and, preferably, their reuse. High-temperature pyrolysis enables satisfactory degradation or recovery of valuable components. High temperatures are advantageous because temperature regimes above 700-800 \({}^{\circ}\)C allow for the thermal cracking of molecules into compounds with lower oxidation states, which is advantageous, for example, from an energetic standpoint. The high temperature, causes high energy costs, making the process more expensive and, as a result, less lucrative. As a result, several types of strategies aimed at lowering energy consumption, such as heat recovery and recirculation, are required to boost the process's cost-effectiveness.