Enhancing Mechanical, Thermal, and Rheological Properties of Recycled Polyethylene via Nano-Calcium Carbonate Reinforcement

The increasing demand for polyethylene has also led to a large amount of waste generated from this polymer, posing numerous environmental and economic challenges. Due to its high chemical stability, polyethylene waste is difficult to decompose and can remain in the environment for decades, leading to soil and water pollution.This study investigates the effect of incorporating nano-CaCO₃ into recycled polyethylene (rPE) composites. Due to extensive industrial use, polyethylene constitutes a significant portion of plastic waste, and its recycling often leads to reduced mechanical and thermal performance. The aim of this work was to improve the quality and durability of rPE by nanoparticle reinforcement, enabling efficient reuse in multiple recycling cycles.rPE samples containing 0–10 wt% CaCO₃ nanoparticles were prepared via melt blending and twin-screw extrusion. Mechanical (tensile strength, Young’s modulus, hardness), thermal (oxidation induction time, thermal expansion, DSC, TGA), and rheological (melt flow rate) tests were performed, complemented by microscopic analysis. Statistical analyses were conducted using one-way ANOVA and Duncan’s test.Results showed that 5 wt% CaCO₃ yielded optimal performance, increasing tensile strength and hardness, improving thermal stability, reducing thermal expansion, and maintaining favorable melt flow properties. Post-recycling tests indicated that nanoparticle-filled samples retained ~90% of their original mechanical properties after three recycling cycles, whereas neat rPE retained only 75%. Microscopy confirmed uniform nanoparticle dispersion at optimal loading, while higher concentrations led to agglomeration and reduced performance.These findings demonstrate that nano-CaCO₃ reinforcement is a cost-effective and environmentally beneficial approach to enhance recycled polyethylene properties, supporting sustainable polymer recycling and circular economy initiatives.