Precipitation 3D printing of all-aramid materials for high-strength, heat-resistant applications

• Precipitation 3D printing of all-aramid structures was achieved. • The aramid nanofiber (ANF) approach and the sulfuric acid approach were compared. • The ANF approach can produce all-aramid materials with compact microstructures. • The all-aramid 3D structures have outstanding mechanical and thermal properties. Additive manufacturing (AM) of lightweight, high-performance engineering polymers is an important research focus in the automotive, electronics and aerospace industries. Aramid material is a highly crystalline polymer in the form of fibers with superior mechanical and thermal properties than most high-performance thermoplastics used in AM. However, manufacturing all-aramid 3D structures has been challenging due to the processing difficulty of aramid. In this work, AM of all-aramid 3D structures is achieved by two approaches: simultaneous protonation and precipitation printing of aramid nanofiber (ANF) colloids, and precipitation printing of aramid/sulfuric acid liquid crystalline solutions. After comparison, the ANF approach proves superior to the sulfuric acid method, offering enhanced printability, greater mechanical strength in the printed parts, and improved capability for microstructure customization. Specifically, the dense all-aramid structures produced through the ANF approach exhibit exceptional mechanical properties, with a Young’s modulus of 7.2 GPa and a tensile strength of 146.6 MPa, outperforming other unfilled, high-performance polymers manufactured through AM. These structures are also capable of withstanding extreme environments, including temperatures up to 350 °C. Therefore, high-performance all-aramid 3D structures can be realized via ANF-based precipitation 3D printing, which can be used as lightweight structural or heat protection parts in aircraft and automotive systems.