Sustainable Polymer Composites: Recycled LDPE/LLDPE Reinforced with Pineapple Leaf Fibre

Abstract

The substantial generation of plastic waste has drawn researchers' attention toward developing environmentally friendly bio-composite materials through polymer recycling. Among synthetic polymers, recycled low-density polyethylene (rLDPE) and recycled linear low-density polyethylene (rLLDPE) are notable for their cost-effectiveness, reduced density, superior surface hardness, and excellent electrical insulation properties. However, they suffer from reduced mechanical strength and quality due to chain degradation and contaminants. This research aims to produce a composite by incorporating sustainable pineapple leaf fiber (PALF) as reinforcement in an rLDPE/rLLDPE blend. The methodology involved processing PALF to ensure uniformity and purity, then blending it at 5%, 10%, 15%, and 20% ratios. The composites were compounded using a laboratory melt mixer at 150 °C and 40 rpm. Tensile and impact strengths, density, water absorption, and chemical interactions (via Fourier Transform Infrared (FTIR) spectroscopy) were examined. Results showed that tensile strength reached 27.7 MPa at 10% PALF, while Young’s modulus increased to 1072 MPa at 20% PALF. Impact strength decreased to 17 kJ/m², whereas density increased to 1.25 g/cm³ at 20% PALF. Water absorption also increased with increasing PALF loading. Overall, the incorporation of PALF increased the composite stiffness, with Young’s modulus reaching 1072 MPa, while density increased to 1.25 g/cm³ and impact strength decreased to 17 kJ/m² at 20% PALF loading.