Translation of innovations developed from fundamental research to commercial products is commonly hindered by the costs associated with the scale-up and development of manufacturable processing routes. An integrated approach where concepts of scale-up, efficient processing, and cost are applied from the beginning of the research project will be described in the context of addressing defined commercializable problems in additive manufacturing of plastics. For most engineering applications, the material requirements are described in terms of mechanical properties of the part. However for additive manufacturing (3D printing) of plastics, the mechanical properties tends to be inferior to those obtained from traditional processes, such as injection molding. The poor mechanical properties can be associated with the layer-by-layer nature of the build that provides a source for failure through the interfaces. One of the most cost-efficient 3D printing methods for polymers is fused filament fabrication (FFF) where a thermoplastic filament is used as the feedstock and is selectively deposited as a melt to build the desired part. The outcome of this processing is a part that is effectively 100% weld lines, which can lead to more than an order of magnitude decrease in the mechanical properties depending on the development of the interface between deposited filament strands. Novel analysis of the print process to elucidate the flow and temperature history provides insight into why defects can develop under certain processing conditions. One solution could be to maintain the polymer in the melt longer to improve the interfaces, but this increased mobility of the polymer will also lead to deformation of the part as it flows under the influence of gravity. Thus, a trade-off generally exists between the mechanical properties and dimensional accuracy of the part. A route to overcome this trade-off is developed through the processing of commercial commodity plastics into core-shell filaments where the core acts to provide mechanical support to the printed structure while the shell is selected to maximize the interfacial strength of the welds. Through this design, plastic parts with impact properties equivalent to injection molded polycarbonate can be obtained. Through this design, we can print parts that contain 50% polyolefin with dimensional accuracy reviling the best commercialized materials, but providing the potential to dramatically decrease feedstock costs. Future outlook for how materials design can be used to improve properties of 3D printed parts while lowering costs will be discussed.
Bryan D. Vogt is currently a professor in the Department of Polymer Engineering at the University of Akron. His research interests center around polymer processing and polymers at interfaces. Areas of particular interest include use of block copolymers as templates for functional materials, materials innovation for 3D printing, polymers in nanoconfinement, and structure-properties of hydrophobically modified hydrogels. He received a B.S. in Chemical Engineering from Michigan Technological University and a Ph.D also in chemical engineering from the University of Massachusetts-Amherst in 2003. He was the recipient of an NRC postdoctoral fellowship in 2002 at NIST in the Polymers Division, where he spent 4 years prior to starting his independent academic career. He is a member of ACS (PMSE Division), AIChE (MESD), and APS. He currently serves as an Associate Editor for ACS Applied Polymer Materials. His prior leadership roles in national organizations include stints as the chair of both the polymers area and the materials engineering and science division (MESD) for AIChE. He has served on the publicity and fellowship committees for DPOLY in APS. He is currently a member at large for PMSE (ACS).