Three-Dimensional-Printed Sustainable Biochar-Recycled PET Composites

Recently, the demand for high-performance, 3D-printable polymer composites has grown exponentially. The objective of this work is to develop a novel low cost and sustainable biochar-recycled poly(ethylene terephthalate) (PET) composite with improved mechanical and thermal performance. Biochar was derived from the pyrolysis of packaging waste at a high temperature and autogenic pressure. The typical temperature and pressure of the reaction are ∼1100 °C and 150 bar. Biochar was ground and sieved to below 100 μm, and it was melt compounded with recycled poly(ethylene terephthalate) derived from postconsumer PET bottles (Aquafina). Biochar/PET composite filaments of 1.75 mm were produced using a melt extruder. The filaments were used to 3D print tensile, DMA, and TMA sample coupons using a Hyrel 30 M printer. Biochar was analyzed for its textural properties, thermal stability, and surface morphology. The as-prepared polymer composite was studied for its thermal, mechanical, and dynamic mechanical properties. These results showed that the incorporation of biochar improved the composite mechanical, thermal, and dynamic properties. A 0.5 wt % biochar infusion in PET resulted in a 32% increase in tensile strength. The polymer composite with 5 wt % loading has shown a 60% increase in tensile modulus over neat PET. Moreover, biochar has significantly improved the composite dynamic modulus, dimensional stability, and thermal stability in an oxidative environment.