(790b) Effects of a functionalized CNC on the rheological properties and printing behavior (Direct Ink Writing (DIW) of an epoxy resin

In this work we characterize the effects of a functionalized CNC on the rheological properties and printing behavior (Direct Ink Writing (DIW)) of an epoxy resin. CNC functionalization is achieved by grafting an activated medium chain fatty acid to substitute the hydroxyl functional groups. The level of CNC modification is evaluated using Fourier Transform Infrared (FTIR), thermo-gravimetric analysis (TGA), X-ray diffraction (XRD), and solvent dispersibility studies. Functionalized CNCs are dispersed into the epoxy resin (EPON 828) at loadings up to 20 wt%. Initially, rheological studies are used in this study to assess the printability of the inks. The rheological percolation threshold is the critical concentration at which there is a transition from liquid-like to solid-like behavior. For this system, this value was found to be at ~10wt%. We found that for the final printed structure to exhibit structural integrity, it is necessary to print at loadings slightly above this value. Future work will include microscopy (SEM and polarized light) of both printed and cast samples to observe the dispersion and alignment of the CNCs within the polymer matrix. Finally, the mechanical properties of all samples will be measured to show the effect of the reinforcement in the matrix.