College - Author 1

College of Engineering

Department - Author 1

Materials Engineering Department

Degree Name - Author 1

BS in Materials Engineering



Primary Advisor

Jean Lee, College of Engineering, Materials Engineering Department


Globally, only 9% of plastic by mass is recycled. Allowing consumers to directly convert polyethylene terephthalate (PET) waste into 3D filament can increase the recycling rate by reducing contamination and costs from traditional large-scale recycling methods. This was tested by heating strips of PET to various temperatures within its glass transition region and pressing a roller with a 1.75 mm indentation against it to observe strip deformation. PET was also placed in a hemispherical well with a 1.75 mm diameter hole at the bottom and heated above its melting temperature to determine the mass of PET required to extrude 3D printer filament using gravity. The filament had the best properties when produced at 175 °C, and 12.5 g of PET were required for gravity extrusion in a 5 cm diameter well. Additionally, replacing polylactic acid (PLA) infill material with a wheat straw pulp can reduce plastic consumption for 3D printed parts while still providing structural support. The viability of this substitution was observed by compression testing a 3D printed PLA frame with 50% wheat straw infill by volume. The results were compared to a PLA frame with equivalent PLA infill by mass and a PLA frame with no infill. Wheat straw was determined to be a viable alternative for PLA infill in parts with low strength requirements; however, shrinking during drying made accurate infill printing difficult.