INTEGRATING THERMOCHEMICAL AND PHYSICAL PROCESSES TO TRANSFORM PLASTIC WASTE INTO VALUE-ADDED PRODUCTS
Name: MIRIAM SUELY KLIPPEL
Publication date: 03/10/2025
Examining board:
Name |
Role |
|---|---|
| TAREK RASHWAN | Examinador Externo |
Pages
Summary: The growing plastic waste crisis demands not only behavioral changes but also the development of sustainable technological solutions. Due to the limitations of mechanical recycling—such as material degradation and loss of quality—this thesis explores an alternative route through thermochemical processing using a combustion-driven pyrolysis reactor. Among the resulting fractions, a waxy by-product was identified as an energy-dense material with promising potential for circular economy applications, particularly for decentralized recovery and ease of transport. However, the limited adoption of this fraction is mainly due to insufficient post-treatment processes, which compromise its purity and consistency. To address this, the thesis proposes an integrated strategy that combines thermo- chemical conversion with physical post-treatment under high pressure to enhance
the value of waxy by-products. A systematic literature review was first conducted to identify the key physicochemical caracteristics and analytical methods used to classify waxes in commercial applications. In parallel, a novel reactor configura-
tion—the Open-Combustion-Driven Pyrolysis Reactor (O-CDPyR)—was designed and tested to improve wax recovery efficiency. The recovered material was charac-terized using thermal, molecular, and rheological analyses to assess its similarity to polyethylene-based commercial waxes.
To further increase the structural order of the material, a two-wall piston–cylinder-type high-pressure cell was developed, capable of operating up to 4 GPa at room temperature. When subjected to high pressure, the waxy material exhibited increased crystallinity and molecular reorganization, suggesting partial repolymerization and potential for upcycling into higher-value polymeric products. These results demonstrate that the integration of smoldering-based pyrolysis and solid-state modification offers a viable pathway for converting undervalued by-products into functional materials, contributing to sustainable material design and circular economy strategies.
Keywords: Smoldering reactors, Waxy product, Characterization, High-pressure, Circular economy of plastic
