Additive “4D” Rheoprinting for the Manufacture of Enhanced Biomaterial Products

A. Duhduh, I.H. Jaafar, J.P. Coulter
Lehigh University,
United States

Keywords: rheology, 3D printing, polymer processing

Summary:

A novel additive manufacturing technique, which we have coined as the “4D Rheoprinter”, has been developed. This technique enables 3D printing of polymers with tunable material properties for optimized performance in wide range of applications. This paper presents how a conventional 3D printing technology is augmented with a system that allows precise control of the rheological dynamics that underlie molecular orientation evolution during the additive manufacturing process. Specific processing parameters that are controlled include shear rate, temperature, and cooling rate. These parameters are shown to have direct impact on the crystallization behavior and molecular orientation of the extruded polymer. Molecular orientation is shown to have significant influence in determining the mechanical, optical, thermal, and biodegradation properties of polymeric materials. The ability to tune this parameter widens its potential use in a wide range of applications. Although additive manufacturing has set new standards on ease of use and have minimal restraints in manufacturing complex geometries, the mechanical properties of 3D printed products are still inferior to those manufactured via conventional methods such as injection molding. 4D Rheoprinting may provide an advantage for 3D printing products, for use in niche applications. Samples have been made and collected using this technique. Material characterization results show that the method can be used to control the crystallinity and molecular structure of the printed part.