Extrusion-based 3D printing with rapidly hardening polymeric materials is capable of building almost any conceivable structure. However, concrete, one of the most widely used materials for large-scale structural components, is generally based on inorganic binder materials like Portland cement. Unlike polymeric materials, a lack of precise control of the extent and rate of solidification of cement-based suspensions is a major issue that affects the ability to 3D-print geometrically complex structures. Here, we demonstrate a novel method for controllable-rapid solidification of concentrated mineral suspensions that contain a polymer binder system based on epoxy and thiol precursors as well as one or more mineral fillers like quartz and calcite. The thermally triggered epoxy-thiol condensation polymerization induces rapid stiffening of the hybrid suspensions (0.30 ≤ ϕ ≤ 0.60), at trigger temperatures ranging between 50 °C and 90 °C achieving average stiffening rates up to 400 Pa/s. The use of nucleophilic initiators such as 1-methylimidazole provides control over the activation temperature and curing rate, thereby helping to achieve an adjustable induction period and excellent thermal latency. By using multiple techniques, we provide guidelines to create designer compositions of mineral suspensions that utilize thermal triggers to achieve thermal latency and ultrafast stiffening – prerequisite attributes for 3D-manufacturing of topologically-optimized structural components.
S. Bhagavathi Kandy et al., "Ultrafast Stiffening of Concentrated Thermoresponsive Mineral Suspensions," Materials and Design, vol. 221, article no. 110905, Elsevier, Sep 2022.
The definitive version is available at https://doi.org/10.1016/j.matdes.2022.110905
Materials Science and Engineering
Keywords and Phrases
3D printing; Additive manufacturing; Epoxy-thiol polycondensation; Stimuli-responsive suspensions; Thermoresponsive suspensions; Ultrafast stiffening
International Standard Serial Number (ISSN)
Article - Journal
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01 Sep 2022