Materials, Methods & Technologies, Volume 19, 2025

Streszczenie: Preparation of well-dispersed recycled polyethylene terephthalate-organoclay nanocomposites with enhanced processing and mechanical properties remains a significant challenge due to the low thermal stability of organoclays. This issue is particularly critical during the melt compounding process, where high temperatures are required to process recycled PET. At elevated temperatures, organoclays, especially those modified with traditional quaternary ammonium salts, tend to degrade, releasing volatile byproducts such as ammonia and other decomposition products. This degradation not only compromises the thermal stability of the nanocomposite but also accelerates the degradation of the recycled PET matrix itself, leading to a reduction in molecular weight and deterioration of mechanical properties. The low thermal stability of organoclays is primarily attributed to the organic modifiers used to render the hydrophilic clay compatible with the hydrophobic polymer matrix. These modifiers, while effective in improving clay dispersion, often decompose at temperatures below the processing range of PET, which typically exceeds 250°C. As a result, the development of thermally stable organoclays is essential to overcome this limitation and achieve the desired improvements in nanocomposite performance. In this study, an overview of various surface modification techniques for sodium-type montmorillonite was conducted to enhance its compatibility with recycled PET. Surface modifications included the use of organic modifiers, such as quaternary ammonium salts, and other innovative approaches aimed at improving the dispersion of the clay within the polymer matrix. The thermal stability of the organoclays and the resulting nanocomposites was evaluated using melt rheology, which provided insights into the degradation behavior and processability of the materials. The results demonstrated that organoclays modified with alternative surface treatments exhibited superior performance compared to those modified with conventional quaternary ammonium compounds. Specifically, the newly prepared clays significantly suppressed matrix degradation during melt mixing, which is a common issue in the processing of PET. The findings suggest that the use of advanced surface-modified clays can open new avenues for the development of high-performance recycled PET-based nanocomposites, which can be utilized in a wide range of applications, including packaging, automotive components, and construction materials. This approach aligns with the growing demand for sustainable materials and the circular economy by adding value to recycled plastics while reducing environmental impact.