Date of Award


Degree Type

Honors College Thesis

Academic Program

Polymer Science and Engineering BS


Polymers and High Performance Materials

First Advisor

Jeffrey Wiggins, Ph.D.

Advisor Department

Polymers and High Performance Materials


The field of additive manufacturing has gained significant academic interest in the past few decades with a recently developed type of three-dimensional (3D) printing. Reactive extrusion additive manufacturing combines precursor materials within a static mixer (SM) head, where polymerization begins before deposition. Variable static mixer geometries currently exist, but the relationship between mixer geometry and post-polymerization mechanical properties is undefined. To elucidate this relationship, a series of experiments with identical chemistry was performed using a high shear SM, a low shear SM, and a comparative batch reaction. While higher shear mixing trends with faster polymerization for step-growth polymerizations, consistent precursor chemistry is expected to yield identical polymer properties. Therefore, polyurethane conversion and viscosity-evolution were elucidated by performing Fourier transform infrared spectroscopy (FTIR) and rheology analyses. Post-polymerization thermomechanical properties were determined through dynamic mechanical analysis. Initially hypothesized that higher shear SM geometry would grant accelerated viscosity growth, the batch reaction achieved a storage-loss modulus crossover first, while the high shear rate optimixer (HSO) geometry had a faster crossover time than the low shear spiral (LSS). Post-polymerization properties remained fairly consistent, but some discrepancies arose, necessitating future studies to prove the root cause of the differences. The results in this research further additive manufacturing by systematically studying the influence of static mixer geometry on polyurethane properties.