This study investigated the chemical recycling of poly(ethylene terephthalate) (PET) fiber residues from two sources—high-molar mass mooring ropes and low-molar mass textile-grade fibers—to produce functional oligomers. Glycolysis was carried out using polyethylene glycol (PEG400) as the depolymerizing agent, and two catalysts were assessed, zinc acetate and lithium octoate, with the latter reported on for the first time in this application. Reactions were performed for 180 min under mechanical stirring, inert atmosphere, reflux, and controlled heating. The resulting oligomers were characterized by Fourier-transform infrared spectroscopy (FTIR), hydroxyl and acidity indices, and thermogravimetric analysis (TGA). Both PET feedstocks showed high reactivity toward glycolysis. Monitoring the reactions by acidity index indicated that conversion reached equilibrium at approximately 120 min. ATR-FTIR confirmed the formation of ester and hydroxyl groups, consistent with oligomer structures. Glycolysis of PET derived from mooring ropes produced oligoesters with hydroxyl values of 228 and 242 mgKOH/g for zinc acetate and lithium octoate, respectively, and molar masses of 1296 and 1338 g/mol for zinc acetate and lithium octoate, respectively. These values are suitable for subsequent syntheses such as polyester polyol production.

Decommissioning Offshore Floating Production Storage and Offloading (FPSO) platforms is a process that requires technical expertise in a variety of technical endeavors. The mooring systems of FPSO platforms use high-tenacity polyester yarn, which is based on high molecular weight polyethylene terephthalate (PET). They are of high value and shouldn’t be thrown away like any other trash. The present study aims to evaluate the development of new materials based on post-consumer polyethylene with the addition of different content of PET fibers (0, 5, 10, and 15 wt.%) processed by fusion in a twin-screw extruder with a side feeder. The processing conditions were set so that the polyester remained in the fiber shape in the melt bulk. In a second step of the study, a compatibilizer agent (polyethylene grafted maleic anhydride—PE-g-MA) was added in the PE/PET fiber blends to evaluate the improvement in the interaction between phases. Mechanical, rheological, and morphological analyses were carried out and showed that PE/PET fiber blends are promising structured materials to be used for the development of new materials with different properties. This study is in line with the goals of the global circular economy.

This study compares the morphology, thermal, and dynamic-mechanical properties of composites based on polybutylene adipate terephthalate/polylactide biocomposites with sponge gourd waste treated code as R, and non-treated sponge gourd, coded as NR, by mechanical disc refining after milled process. Extrusion followed by compression molding was used to produce biocomposites with fiber contents of 0, 2.5, 5, 10, and 15% wt/wt for R and NR sponge gourd fibers. Scanning electron microscopy analysis reveals that NR has the morphology of a rigid tubular shape, whereas R is a thinner, twisted, and fibrillated fiber. Regardless of the type of sponge gourd fiber used, the thermal stability of the composite decreases as the sponge gourd content increases. At 25°C, the biocomposite with 10%wt/wt R fiber has the highest storage modulus value. The comparison of Tangent  peak values reveals that the presence of sponge gourd fibers reduces the energy dissipation of the biocomposites. The analysis of the loss modulus at 25°C reveals that R fiber contributes more to the reduction of energy dissipation of the biocomposites than NR. Furthermore, the Cole-Cole plot shows that R and NR fibers are dispersed and do not significantly change the homogeneity of the biopolymer systems.

The growing volume of plastic and agro-industrial waste, such as coconut shells, poses significant environmental and social challenges, demanding innovative solutions aligned with national solid waste policies and the circular economy. The objective of this study focused on developing sustainable plastic wood by adding post-consumer polypropylene waste and coconut fibers (PP-PCR/CF). To achieve this goal, the PP-PCR/CCF composites were processed by extrusion and injection molding, and characterized by melt flow index (MFI), impact and tensile strength and thermal analysis (TGA and DSC analysis). Results indicate that the addition of coconut fibers does not significantly impair the thermal stability or mechanical properties of the PP-PCR matrix, even at higher fiber contents. While crystallinity and flow behaviour are influenced by fiber content, the composites retain adequate performance for practical applications such as benches, coatings and decks. The work highlights the alignment of this approach with Brazil's National Solid Waste Policy (PNRS) and the principles of the circular economy, offering benefits such as reduced landfill waste, decreased CO₂ emissions, and valorisation of agricultural by-products. This work reinforces shared responsibility in the product life cycle, transforming disposal challenges into innovative and high-value solutions, and contributing significantly to sustainability and the circular economy.