Room Temperature Extrusion 3D Printing of Polyether Ether Ketone Using a Stimuli-Responsive Binder

We report 3D printing of polyether ether ketone (PEEK) at room temperature by direct-ink write technology. The room-temperature extrusion printing method was enabled by a unique formulation comprised of commercial PEEK powder, soluble epoxy-functionalized PEEK (ePEEK), and fenchone. This combination formed a Bingham plastic that could be extruded using a readily available direct-write printer. After printing, thermal processing at 230 °C resulted in crosslinking of the ePEEK components to form a stabilizing network throughout the specimen. A final sintering stage was conducted at 380 °C. The T_g of product specimens was found to be 158 °C, which is 13 °C higher than commercial PEEK as measured by DSC. Moreover, the thermal decomposition temperature was found to be 528 °C, which compares well against commercial molded PEEK samples. Chemical resistance in trifluoroacetic acid and 8 common organic solvents were investigated, and no signs of degradation were observed from parts submerged for 1 week in each solvent. Test specimens also displayed desirable mechanical properties, such as a Young’s modulus of 2.5 GPa, which corresponds to 63% of that of commercial PEEK.