Developing Filament Extruder and Characterization of Recycled High-Density Polyethylene for 3D Printing Filament Material

Abstract

With the rise of additive manufacturing, the demand for 3D printing feedstock has increased exponentially and its sustainability is critical in the future. Many scholars are now concerned about how 3D printing filaments should be reproduced from recycled plastic. This study aimed to develop a filament extruder machine and investigate the potential of using recycled high-density polyethylene (HDPE), one of the most commonly used and recyclable thermoplastic, for 3D printing filament material. Desktop sized filament extruder machine was built, and a smooth and round-shaped 1.75±0.01mm diameter recycled HDPE filament was produced. Its mechanical, thermal, chemical, and physical properties were characterized by conducting various tests and validation test was conducted by comparing its properties with its virgin counterpart. The ultimate tensile strength of the recycled HDPE filament was obtained 19.02±0.35MPa, which is comparable to the ultimate tensile strength of virgin HDPE, making it a viable 3D printing feedstock for rapid prototyping. According to Thermogravimetric analysis (TGA), the recycled HDPE filament offers significant thermal stability with an onset degradation temperature of 430℃ and a full degradation temperature of 520℃. Its Fourier Transform Infrared (FTIR) spectrum shows the same functional groups as virgin HDPE polymer. The recycled HDPE filament has also excellent water-rejecting capability. In general, the study revealed a promising result for the use of recycled HDPE plastic as a more sustainable and environmentally friendly source material for 3D printing filament. To increase the potential and market competitiveness of recycled filaments, further investigation is required to optimize the filament extrusion and 3D printing process parameters, improve the mechanical properties, and overall development methods for both the recycled HDPE filament and 3D printed products.