A thermoreversible thermoset formed by Diels-Alder (DA) chemistry was used in Fused Filament Fabrication (FFF) 3D printing to obtain a printable, elastic thermoset with isotropic mechanical properties. FFF additive manufacturing typically uses thermoplastics that are limited in the amount of filler that can be incorporated in composite prints due to their high melt viscosities and often exhibit anisotropic strengths according to the print geometry.  Thermoreversible thermosets with weak links based on cycloadducts between maleimide and furan groups can revert from crosslinked network to liquid oligomeric resins with heating above 100 °C.  In this study, filaments with up to 60wt% tricalcium phosphate and silica particles were prepared and used in FFF printing.  Thermoreversible resins were prepared by reacting 1,1'-(methylenedi-4,4'-phenylene)bismaleimide (MPB) with furfuryl group functionalized oligomeric Jeffamines.   The resulting resins were then heated to mix with particle filler and extruded to afford 1.75 mm filament.   Tensile test specimens were printed between 130-150 °C with varying printing geometries to establish that the thermoreversible thermosets displayed isotropic strength relative to print orientation.   The resulting printed structures were readily recyclable by chopping into fragments and re-extruding as filament for additional printing.  The resins can be recycled back into filament and then printed up to five times.  Irreversible crosslinking, through reaction of free maleimides, occurs after 5 hours at 140 °C but could be used to prevent thermoreversion.  Properties of the resins could be tuned with filler content and with the molecular weight of the jeffamine.<br/>

Fused filament fabrication using a Diels–Alder reversible thermoset: Novel isotropic 3D printable material with high filler content

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.