3D Printing of Sustainable Coal Polymer Composites: Study of Processing, Mechanical Performance, and Atomistic Matrix–Filler Interaction

Abstract

Bituminous coal was utilized as a particulate filler in polymer-based composites to fabricate standard 1.75 mm coal-plastic composite filaments for material extrusion 3D printing. The composites were formulated by incorporating Pittsburgh No. 8 coal into polylactic acid, polyethylene terephthalate glycol, high-density polyethylene, and polyamide-12 resins with loadings ranging from 20 to 70 wt %. Coal-plastic composite filaments were extruded and printed by using the same processing parameters as the respective neat plastics. The introduction of coal ameliorated the warping problem of 3D printed high-density polyethylene, allowing for additive manufacturing of an inexpensive and widely available thermoplastic. The mechanical properties of the 3D printed composites were characterized and compared to those of composites fabricated using traditional compression molding. Microscopy of as-fractured samples revealed that particle pull-out and particle fracture were the predominant modes of composite failure. Tensile and flexural moduli as well as hardness had direct proportionality with increasing coal content, while flexural strength, tensile strength, and impact resistance decreased for most composite formulations. Interestingly, polyamide-based composites demonstrated greater maximum tensile and flexural strengths than unfilled plastic. Investigation of composite interfacial chemistry via molecular dynamics simulations and Fourier-transform spectroscopy revealed beneficial hydrogen bonding interactions between coal and polyamide-12, while no chemical reactions were evident for the other polymers investigated.

Additive Manufacturing of a Super Toughened Biodegradable Polymer Blend: Structure–Property-Processing Correlation and 3D Printed Prosthetic Part Development

“…The emergence of additive manufacturing (AM) technologies has opened up new opportunities for the production of sustainable and eco-friendly products using biodegradable polymers and their blends. , Among the most commonly used AM techniques is fused filament fabrication (FFF), also known as fused deposition modeling (FDM). A new phrase, “extrusion deposition”, has emerged in recent years to describe the latest developments in industrial printers that deposit material pellets by melting them in an extruder. , The study by Ou-Yang et al highlighted the suitability of PLA/PBS blends with low crystallinity, moderate viscosity, and high modulus for FDM printing. Increasing the PBS content in the blends improved interlayer bonding by decreasing the zero-shear viscosity.…”

Computer simulation of carbonization and graphitization of coal

“…Carbon foams are renowned for their exceptional mechanical, electrical, and thermal properties, making them highly desirable for a wide array of engineering applications [16]. Moreover, there is a growing interest in using coal as filler material in composites to enhance the mechanical properties of polymers [17,18], as well as to improve the electrical properties of metals [19]. The latter is exemplified by successful cases using polycrystalline graphene composites with copper [20] and aluminum [21].…”