(565c) Xpcs Studies of a Cellulose Nanocrystal Thermoset Ink during Extrusion Printing
In this work, using state of the art scattering techniques at the National Synchrotron Light Source at the Brookhaven National Lab (BNL), we address the dispersion of surface-modified CNC in a commonly used epoxy resin (EPON 828) and explore processing such composites through direct-ink write (DIW) printing with a DIW printer installed on the beamline. X-ray photon correlation spectroscopy (XPCS), coupled with shear rheology studies, is utilized to study the morphology and dynamics before, during, and after printing of a naturally hydrophilic CNC particle in a mostly hydrophobic thermosetting epoxy resin. The hydrophobicity of the particles was varied over three different concentrations, allowing for a systematic increase of grafting on the surface of the particles. Each level of surface modification was dispersed into the EPON resin at loadings up to 40 wt%. The rheological measurements revealed a clear distinction in macroscopic properties (viscosity, viscoelasticity, recovery) due to changes in the particle-particle and particle-matrix interactions amongst the different levels of modification. Additionally, results from the XPCS studies show drastic changes in the dynamics of the particles as a function of surface modification during the recovery of the material after printing. Results from the scattering studies are then correlated with the macroscopic properties (tensile strength) after printing to delineate the underlying structure-function relationships. Our in-operando results provide insight into the importance of understanding the microstructure properties of such materials to allow for the development of enhanced polymeric nanocomposites.