Extrusion-based
additive manufacturing methods, such as direct-write
of carbon fiber-reinforced epoxy inks, have become an attractive route
toward development of structural composites in recent years, because
of emerging techniques such as big area additive manufacturing. The
development of improved materials for these methods has been a major
focus area; however, an understanding of the effects of the printing
process on the structural and dynamic recovery in printed materials
remains largely unexplored. The goal of this work is to capture multiscale
and temporal morphology and dynamics within thermosetting composite
inks to determine the parameters during the printing process that
influence the recovery of the printed material. Herein, we use X-ray
photon correlation spectroscopy in small-angle scattering geometry
to reveal both morphology and recovery dynamics of a nanoparticle
(layered-silicate Cloisite 30B) in a thermoset epoxy resin (EPON 826)
during the printing process in real time. Our results show that the
dynamics of the layered silicate particles during recovery are anisotropic
and slow down to behavior which is characteristic of aging in
colloidal clay suspensions around t
age ≈ 12 s. The dynamics and alignment of the particles during
recovery were tempo-spatially mapped, and the recovery post printing
was shown to be strongly influenced by the deposition onto the build
plate in addition to the extrusion through the print head. Our in
operando results provide insight into the parameters that must be
considered when optimizing materials and methods for precisely tailored
local properties during 3D printing.
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