Graduate Students - Osswald

Lukas Duddleston

Email
lduddleston@wisc.edu

Advisor
Professor Osswald

Education
Expected: Ph.D., Materials Science, Univeristy of Wisconsin-Madison (2018)

M.S., Mechanical Engineering, University of Wisconsin-Madison (2015)

B.S., Chemistry, Edgewood College, Madison, Wisconsin (2013)

B.S., Biology, Edgewood College, Madison, Wisconsin (2013)

Experience
USDA - FS - Forest Products Lab (2011 to 2013)

Hometown
Madison, Wisconsin

Hobbies
Skiing, Refeering Soccer

Research Interests

My PhD work explores the role of processing parameters during PVC extrusion on the foam behavior of azo-compounds. This experimental work includes the development of custom analytical instrumentation capable emulating an extrusion process while allowing for collection of data not possible on an extruder. The goal of the work is to better predict the influence of material properties and machine parameters on the foaming process to better control the morphology of the foamed polymer.


My master's thesis was in the field of Selective Laser Sintering (SLS), specifically thermal analysis and spectrochemical characterization of the powder.

SLS, a 3-dimensional printing technique, converts powdered thermoplastic resins, e.g. polyamide 12 (nylon), into end-use parts using a laser to melt and fuse the particles. In this layer-by-layer additive manufacturing process the powder is both the raw material and the mold material. Therefore unsintered powder can be recovered and recycled in subsequent builds to significantly decrease net costs. However, unsintered powder is thermally degraded, which results in inferior parts unless blended (refreshed) with virgin powder. To improve blending protocols, the powder quality was quantified using differential scanning calorimetry (DSC), thermogravimetric analysis, and the melt flow index (MFI) for molecular degradation and using flowability measurements to measure changes in bulk properties. The results suggested that the sensitivity of DSC to small changes in molecular weight could reproducibility measure small changes in artificially aged (degraded) powder. Angle of repose, a flowability measurement, and MFI were sensitive to bulk and molecular degradation, respectively; however, both techniques lacked reproducibility. In conclusion, DSC could be a powerful tool to help optimize recycling of SLS powder.



Other areas of research interest include the extrusion of filament during the Fused Deposition Modeling (FDM) 3D printinger process.

Publications

Journal Articles:

Ellingham, T., Duddleston, L. & Turng, L.-S. Sub-critical gas-assisted processing using CO2 foaming to enhance the exfoliation of graphene in polypropylene + graphene nanocomposites. Polymer (Guildf). (2017). doi:10.1016/j.polymer.2017.04.028

Conference Proceedings:

Duddleston, L. J. L. Woznick, K. Koch, C. Mazzei Capote, G. Rudolph, N. Osswald, T. A. Extrudate Mass Flow Rate Analysis in Fused Filament Fabrication (FFF): A Cursory Investigation of the Effects of Printer Parameters. in ANTEC 2017 (2017).

Duddleston, L.J.L. Puck, A.T. Harris, A. Doll, N.P., Osswald, T.A.Differential Scanning Calorimetry (DSC) Quantification of Polyamide 12 (Nylon 12) Degradation during the Selective Laser Sintering (SLS) Process. in ANTEC 2016, (2016).

Master's Thesis:

Duddleston, L.J.L. Polyamide (Nylon) 12 Powder Degradation during the SLS Process: A Quantification for Recycling Optimization. M.S. Thesis, University of Wisconsin-Madison, Madison, WI, 2015.

Other:

Duddleston, L.J.L., Doll, N.P., de Stephanis, E., Puck, A.T., Osswald, T.A., Thermal and Spectrochemical Analysis of Degradation during the SLS Printing Process. Poster presented at: 15th Annual International Polymer Colloquium at the University of Wisconsin-Madison; 2015 March 27; Madison, WI.

Roles

Current
  • Laboratory Manager
  • ME313 Teaching Assistant
  • Safety Officer
  • SPE Student Chapter President
  • Wisconsin Alumni Reserach Foundation (WARF) Ambassador

  • Previous
  • SPE Student Chapter Secretary (2014-2015)
  • Webmaster (2014-2015)
  • ME418 Teaching Assistant (August 2016 to December 2016)
  • ME313 Teaching Assistant (August 2014 to May 2015)



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