Many of the challenges with 3D
printed polymers are due to anisotropy caused by the method in
which FFF printers lay down the material. In FFF, the polymer is
typically melted or melt-extruded through the print head and
deposited onto a growing substrate layer by layer. 3D printed
polymers by FFF are not as reliable as traditional manufactured
parts because poor interlayer adhesion limits toughness and
robustness, especially perpendicular to printed layers. Since materials
are typically melt processed during FFF, crosslinked polymers
systems are traditionally not viable