Molten Embedded Writing of End-Use Thermoplastics for Engineering Applications

Fused filament fabrication has been applied to manufacture complex thermoplastic structures. However, due to the poor mechanical strength, the printed structures are typically used for prototyping purposes rather than end-use functional parts. Inspired by embedded ink writing, which produces three-dimensional architectures with enhanced mechanical properties, a molten embedded writing (MEW) method is developed in this work to print thermoplastic polymer filaments within a high-temperature support bath. The support bath is composed of organomodified montmorillonite particles and high-smoking-point sunflower oil, which offers a desired thermal environment to promote interfilament fusion, thereby enhancing the mechanical strength of as-printed structures. To demonstrate the broad and reliable application of MEW, three representative end-use parts, including orbital implants from polycaprolactone, spigots from polylactic acid for a lab-scale hydrocyclone, and sensors from thermal polyurethane, are successfully printed for repairing an orbital bone fracture, enhancing mineral particle separation, and detecting strain and force for a robotic hand, respectively.