Enhancing structural and thermal properties of low-density polyethylene waste using dolomite and calcite mineral fillers

Abstract

This study investigates the enhancement of waste low-density polyethylene (WLDPE) properties through the incorporation of mineral fillers, specifically dolomite and calcite. Addressing WLDPE waste is critical for reducing environmental impact, and mineral fillers offer a cost-effective and sustainable solution. WLDPE/dolomite and WLDPE/calcite composites were prepared using a solvent-based method at varying filler contents. X-ray diffraction (XRD) analysis confirmed the presence of calcite and dolomite crystalline phases within the polymer matrix. Fourier transform infrared spectroscopy (FTIR) revealed the persistence of characteristic bands of both resin and fillers, with slight shifts indicating interfacial interactions between polymer functional groups and mineral surfaces. Differential scanning calorimetry (DSC) demonstrated a moderate improvement in thermal stability: the decomposition temperature of neat WLDPE (412 °C) increased by 8 °C for 5% calcite and by 6 °C for 10% dolomite, while beyond 15% filler content, the effect became negligible. These findings suggest that weak interactions, consisting probably of van der Waals forces or hydrogen bonds, contribute to slight structural and thermal enhancements. This approach highlights the potential of mineral fillers to upgrade recycled WLDPE, offering a promising pathway for sustainable plastic waste management.