A Co-extrusion Additive Manufacturing Process with Mixer Nozzle to Dynamically Control Blowing Agent Content and...

Area of Science:

• Materials Science
• Additive Manufacturing
• Polymer Foams

Background:

• Functionally graded materials offer tailored properties but fabricating complex foam structures remains challenging.
• Existing additive manufacturing techniques struggle with precise control over foam density gradients.

Purpose of the Study:

• To demonstrate a novel co-extrusion additive manufacturing approach for producing 3D-printed functionally graded foams (FGFs).
• To achieve dynamic control over blowing agent content for programmable density profiles.

Main Methods:

• Utilized a co-extrusion process with a static mixer nozzle (SMN) and thermally expandable microspheres (TEMs).
• Employed two filaments: expandable polylactide acid (ePLA) and neat polylactide acid (PLA).
• Varied filament ratios and flow path lengths to control mixing and foaming.

Main Results:

• Successfully fabricated FGFs with uniform cellular morphologies and densities ranging from 0.43 to 1.21 g/cm³.
• Demonstrated superior mechanical performance of printed FGFs compared to uniform foams and solid counterparts.
• Showcased the influence of flow path length on foam density due to residence time variations.

Conclusions:

• The developed additive manufacturing process is capable of producing complex, functionally graded structures with on-demand density profiles.
• This method offers a versatile platform for creating advanced foam materials with tailored mechanical properties.
• The dynamic control over foaming agent content provides precise control over final material density and performance.