Research in Dr. Mackay’s group concerns materials processing and the structures developed from processing effects. Most of his research centers on processing polymers using fused filament fabrication (FFF), a type of additive manufacturing or 3D printing. Our goal is to develop new materials and processing technologies to make strong products with this new polymer processing technology.
We use sophisticated characterization tools such as small angle neutron scattering (SANS), a technique we have many years of experience using, to understand the structure-property relationship. This technique requires us to use deuterated polymers to measure the radius of gyration. Deuterated polystyrene is blended with protonated polystyrene using a twin screw extruder and we make the filament for FFF. After FFF, we determine the radius of gyration using SANS with the aim of determining how oriented the molecules are in the product and then relate this to its strength. We are interested in generating highly oriented polymers using FFF to improve the product strength. To do this we make new polymers and polymer blends for FFF and optimize the “hot end” of our Taz 3D printers.
Our lab also utilizes rheometry to characterize materials used in FFF. This tool helps us understand why current materials are particularly good in FFF and to design new materials that will have good printing performance. Other tools that we use regularly include dynamic scanning calorimetry (DSC) and thermogravimentric analysis (TGA).
The weld strength between filaments is another aspect of FFF that dictates printed product strength. We have developed heat transfer models to predict the temperature of deposited filaments and relate this to molecular diffusion at the interface and subsequently to the weld strength. More recent work involves the use of new chemistries to form strong covalent bonds between deposited layers, resulting in increased product strength. Other work includes designing new printer heads that can print multiple materials simultaneously to take advantage of both materials’ properties.
In summary, we are using sophisticated techniques to optimize a new processing technique to make the strongest products possible in the shortest amount of processing time.