Towards Sustainable Material Process Technologies: Examining Polymer Property‐Processing Relationships in the Material Extrusion of Plastic Waste‐Blended <scp>HDPE</scp> for Bike Fairing Design and Simulation

ABSTRACT Plastic pollution, driven by the overuse of plastics and inadequate waste management, poses severe environmental and health risks. Despite the potential benefits of recycling, rates remain low due to the high costs of centralized recycling systems and the associated greenhouse gas emissions. Motivated by this challenge, this study explores the reuse of plastic waste for 3D printing as a viable and sustainable alternative. A Brabender melt mixer was used to combine discarded plastic bags and high‐density polyethylene. The resulting composite was processed into 3D printing filaments using a single‐screw extruder. Dumbbell‐shaped specimens were then created by melt extrusion following ASTM D412 specifications. Mechanical properties were tested using a Universal Testing Machine, and morphological features were examined via Scanning Electron Microscopy. The goal is to reduce plastic pollution and encourage innovative recycling practices. Our approach integrates 3D printing with Finite Element Analysis to accelerate product development and minimize material waste, enabling rapid prototyping and design optimization. Optimized prototypes were fabricated through 3D printing for efficient material use. A 5 wt% waste plastic blend demonstrated superior tensile strength and thermal stability compared to pure HDPE. This blend was successfully used to design a bike fairing, validated through AutoCAD and Finite Element Simulation.