3D Printing PTFE with Direct Ink Writing

Abstract

Polytetrafluoroethylene (PTFE) is a unique fluoropolymer comprising of only fluorine and carbon atoms with various desirable properties such as non-stick, chemical inertness, thermal stability and electrical insulation. Molding and sintering techniques following by pressurized preforming are commonly used to cast PTFE for desirable shapes and forms with considerable amount of waste under high cost. However, rapid prototyping and customizable tooling of PTFE is yet developed. Herein, we reported a novel and facile way for PTFE 3D printing by Direct Ink Writing (DIW). PTFE dispersion based composite, with varying amount of Gellan gum additives, was developed as 3D printable ink to generate millimeter features following by multi-steps thermal process. In order to fabricate molding PTFE properties similar structures, the design of experiments (DOE) method based on Taguchi’s orthogonal arrays were applied. The printed structures were prepared by varying three controlled factors including the Gellan gum weight percentage, the maximum temperature, and the cooling rate with three selected levels. An optimal parameter setting is obtained through a desirability function analysis of variance (ANOVA) that balances the desired Young’s modulus and yield strength targets. The Young’s modulus and yield strength are found to be controllable by varying the amount of Gellan gum. Based on its mechanical, hydrophobic and chemical inert properties, tubular structures with various designs were fabricated to demonstrate its potential in medical implants.