Processing, Morphology, and Crosslink Network in Model Liquid Crystalline Thermosets for Additive Manufacturing

The additive manufacturing (AM) of high-temperature thermosetting resins would enable rapid functional prototyping and on-demand production of high-performance aircraft parts; however, limitations of current feedstock materials have prevented AM of such parts to date. The use of liquid crystalline thermosetting polymers could overcome several critical challenges in fused deposition modeling, such as tuning the rheology during print and cure and improving final mechanical properties. The shear-alignment of liquid crystal domains by the nozzle could also allow for the controlled design of anisotropic properties. Here, a model liquid crystal thermoset system based on epoxide chemistry is studied with respect to AM processing. We examine the effect of shear on morphology before, during, and after crosslinking, both in a controlled, uniform shear environment and at the printing nozzle. We explore how viscosity and final morphology (and therefore final properties) can be controlled by exploiting liquid crystallinity.