Sustainable 3D Printing of Recyclable Biocomposite Empowered by Flash Graphene

Programmed multimaterial assembly by synergized 3D printing and freeform laser induction

In nature, structural and functional materials often form programmed three-dimensional (3D) assembly to perform daily functions, inspiring researchers to engineer multifunctional 3D structures. Despite much progress, a general method to fabricate and assemble a broad range of materials into functional 3D objects remains limited. Herein, to bridge the gap, we demonstrate a freeform multimaterial assembly process (FMAP) by integrating 3D printing (fused filament fabrication (FFF), direct ink writing (DIW)) with freeform laser induction (FLI). 3D printing performs the 3D structural material assembly, while FLI fabricates the functional materials in predesigned 3D space by synergistic, programmed control. This paper showcases the versatility of FMAP in spatially fabricating various types of functional materials (metals, semiconductors) within 3D structures for applications in crossbar circuits for LED display, a strain sensor for multifunctional springs and haptic manipulators, a UV sensor, a 3D electromagnet as a magnetic encoder, capacitive sensors for human machine interface, and an integrated microfluidic reactor with a built-in Joule heater for nanomaterial synthesis. This success underscores the potential of FMAP to redefine 3D printing and FLI for programmed multimaterial assembly.

Replacement of Concrete Aggregates with Coal-Derived Flash Graphene

Each year, the growth of cities across developing economies in Asia, Africa, and Latin America drives demand for concrete to house and serve their burgeoning populations. Since 1950, the number of people living in urban areas has quadrupled to 4.2 billion, with another predicted 2.5 billion expected to join them in the next three decades. The largest component of concrete by volume is aggregates, such as sand and rocks, with sand as the most mined material in the world. However, the extraction rate of sand currently exceeds its natural replenishment rate, meaning that a global concrete-suitable sand shortage is extremely likely. As such, replacements for fine aggregates, such as sand, are in demand. Here, flash Joule heating (FJH) is used to convert coal-derived metallurgical coke (MC) into flash graphene aggregate (FGA), a blend of MC-derived flash graphene (MCFG), which mimics a natural aggregate (NA) in size. While graphene and graphene oxide have previously been used as reinforcing additives to concrete, in this contribution, FGA is used as a total aggregate replacement for NA, resulting in 25% lighter concrete with increases in toughness, peak strain, and specific compressive strength of 32, 33, and 21%, respectively, with a small reduction in specific Young's modulus of 11%. FJH can potentially enable the replacement of fine NA with FGA, resulting in lighter, stronger concrete.

Innovative Polymer Composites with Natural Fillers Produced by Additive Manufacturing (3D Printing)-A Literature Review

In recent years, plastics recycling has become one of the leading environmental and waste management issues. Along with the main advantage of plastics, which is undoubtedly their long life, the problem of managing their waste has arisen. Recycling is recognised as the preferred option for waste management, with the aim of reusing them to create new products using 3D printing. Additive manufacturing (AM) is an emerging and evolving rapid tooling technology. With 3D printing, it is possible to achieve lightweight structures with high dimensional accuracy and reduce manufacturing costs for non-standard geometries. Currently, 3D printing research is moving towards the production of materials not only of pure polymers but also their composites. Bioplastics, especially those that are biodegradable and compostable, have emerged as an alternative for human development. This article provides a brief overview of the possibilities of using thermoplastic waste materials through the application of 3D printing, creating innovative materials from recycled and naturally derived materials, i.e., biomass (natural reinforcing fibres) in 3D printing. The materials produced from them are ecological, widely available and cost-effective. Research activities related to the production of bio-based materials have gradually increased over the last two decades, with the aim of reducing environmental problems. This article summarises the efforts made by researchers to discover new innovative materials for 3D printing.

Biomass 3D Printing: Principles, Materials, Post-Processing and Applications

Under the background of green and low-carbon era, efficiently utilization of renewable biomass materials is one of the important choices to promote ecologically sustainable development. Accordingly, 3D printing is an advanced manufacturing technology with low energy consumption, high efficiency, and easy customization. Biomass 3D printing technology has attracted more and more attentions recently in materials area. This paper mainly reviewed six common 3D printing technologies for biomass additive manufacturing, including Fused Filament Fabrication (FFF), Direct Ink Writing (DIW), Stereo Lithography Appearance (SLA), Selective Laser Sintering (SLS), Laminated Object Manufacturing (LOM) and Liquid Deposition Molding (LDM). A systematic summary and detailed discussion were conducted on the printing principles, common materials, technical progress, post-processing and related applications of typical biomass 3D printing technologies. Expanding the availability of biomass resources, enriching the printing technology and promoting its application was proposed to be the main developing directions of biomass 3D printing in the future. It is believed that the combination of abundant biomass feedstocks and advanced 3D printing technology will provide a green, low-carbon and efficient way for the sustainable development of materials manufacturing industry.