Performance of Lignin as Filler in Composites of Low Density-Polyethylene (LDPE) and Lignosulfonate

Abstract

Low-density polyethylene (LDPE)-based composites reinforced with lignosulfonate and lignin were developed to enhance mechanical and thermal properties while supporting sustainability. Tensile testing showed that increasing lignin concentration improved tensile strength, though no significant difference was observed between LL7.5 and LL10 due to possible lignin agglomeration. Differential Scanning Calorimetry (DSC) analysis revealed that all composites had a consistent melting point at 107 °C, while Thermogravimetric Analysis (TGA) showed similar thermal degradation patterns to LDPE (400–500 °C), with lignin-based fillers degrading at 200–400 °C. Melt Flow Rate (MFR) testing demonstrated a decreasing trend with higher lignin content, with LL0 showing the highest value (4.92 g/10 min) and LL10 the lowest (3.53 g/10 min). Fourier Transform Infrared Spectroscopy (FTIR) analysis before and after 30 days of sunlight exposure indicated no significant chemical changes, suggesting good environmental stability. These results demonstrate that incorporating lignosulfonate and lignin enhances both thermal stability and mechanical strength without compromising structural integrity under environmental exposure. The developed composites show promise for industrial applications requiring improved performance and eco-friendly materials.