An Overview on Sustainable Additive Manufacturing from Recycled HDPE and Agricultural Waste Fibre Filaments

Abstract

The increasing demand for 3D printing materials raises significant environmental concerns due to the widespread use of non-biodegradable polymers. This paper presents a systematic review of composite filaments developed from recycled high-density polyethylene (HDPE) reinforced with agricultural waste fibres for use in fused filament fabrication (FFF). A structured methodology was adopted, involving a literature search across peer-reviewed databases (2016–2026) using keywords such as “recycled HDPE filament,” “agricultural fibre composites,” and “FFF additive manufacturing,” with studies selected based on relevance to filament fabrication, mechanical performance, and sustainability outcomes. Recycled HDPE is a promising matrix due to its mechanical durability and recyclability, though challenges such as shrinkage and warping during printing persist. To enhance its performance, various natural fibres, such as melon husk, banana fibre, and hemp are incorporated as reinforcements, leveraging their biodegradability, mechanical strength, and compatibility with polymer matrices. This review analyses filament fabrication techniques, including mechanical recycling, extrusion parameters, and the use of additives to improve fibre-matrix interaction. Performance evaluation methods such as Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and X-Ray Diffraction (XRD) are also discussed in assessing the composite’s mechanical, structural, and thermal behaviour. Reviewed studies show that fibre reinforcement improves tensile strength, reduces warping, and enhances environmental degradability, though excessive fibre content may hinder printability. The integration of agricultural waste in recycled HDPE filaments presents a dual advantage: minimising plastic pollution and valorising agro-waste. The review concludes that agro-fibre-reinforced HDPE filaments hold significant promise for sustainable 3D printing, with further optimisation needed to balance fibre content, print quality, and mechanical performance for commercial applications.