Hazelnut shell carbon filled polylactic acid composite filaments for 3D printing photothermal structures

Abstract

Low-cost, compostable, high-efficiency photothermal conversion materials with shaping freedom into complex geometrical structures have received considerable attention by the photothermal conversion technologies. In this study, a kind of bio-based filament with photothermal conversion function for fused filament fabrication (FFF) technology was prepared by adding hazelnut shell carbon (HSCs) in polylactic acid (PLA) matrix. The HSCs were obtained at 300, 500, 700, and 900 °C. The results revealed that the morphology, particle size, pore structure, surface functional groups, and degree of graphitization of HSCs varied with the pyrolysis temperature. Additionally, the three-dimensional (3D) printability of PLA-HSC composite filaments as well as the photothermal performance of the printed structures were affected by the pyrolysis temperature of HSCs. All PLA-HSC filaments were suitable for 3D printing besides HSC pyrolyzed at 300 °C. Furthermore, the fluidity of the composites increased with the pyrolysis temperature of HSCs. The rheology results demonstrated that the complex viscosity, storage modulus, and loss modulus decreased with the increase of pyrolysis temperature. However, the mechanical properties and the thermal stability of the PLA-HSC filaments showed opposite trend. At the wavelength range of 250–2500 nm, with HSCs pyrolyzed at 700 and 900 °C, the 3D printed PLA-HSC parts demonstrated excellent photothermal performance with a light absorption intensity of around 93 %. Overall, HSCs pyrolyzed at 700 °C is the most cost-effective candidates for the preparation of PLA-based filament for photothermal conversion components. In this work, a brine evaporation crystallizer was 3D printed to demonstrate the application of this filament.