Polymer-Based Materials: Expanding properties through Parts, Processes, and Materials

Frederik Grønborg

Research output: Book/ReportPh.D. thesis

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Abstract

The idea of the thesis was to extend the properties of the materials through the design of parts, processes, and materials to reduce the number of materials needed in a product for a transition toward a circular economy. Polymers and polymer-based materials are attractive for their versatility and cost efficiency. For those same reasons, they have permeated most of the products we use and systems on the planet. As polymers are artificial creations and do not degrade well in nature, they have become the target of rising concerns regarding sustainability and the environmental impact of their pollution. Creating a circular polymer economy is thus becoming ever more relevant, but it is a complex problem to solve. This Ph.D. thesis explores the problem and solutions by expanding the properties through parts, processes, and materials.

The first part of the thesis explores how to create filaments for Material Extrusion Additive Manufacturing (MEX), recycle ocean waste into filaments, and use the fabrication method to study the influence of geometry on flexural-sensor  output. The filamentbased MEX is used to rapidly evaluate the designed material and parts. It was shown that recycling ocean waste for filaments brings problems due to the degraded nature of the material. Using a compatibilizer yielded a printable material but with a high degree of warping. A conductive filament was designed and produced to explore the influence of geometry on the signal output of flexural sensors. The investigation showed that it was possible to use part geometry to extend the properties of the conductive filament. It was possible to increase the change in the measured resistance roughly 28 times when comparing the geometries.

The second part of the thesis explores the use of processing parameters to influence the properties of Thermoplastic Polyurethane (TPU). The most critical finding in this part is the importance of characterization methods. The phase-separating nature of TPU depends on the processing conditions, leading to morphological alterations. These changes in morphology are responsible for changes in properties. It was found that traditional methods would yield a limited picture of the changes from which they could be dismissed. With the use of more novel testing methods, it was found that there is a stiffness gradient through the samples and that the relaxation strength is affected by mold temperature.

The formation of binary polymer blend morphology is explored in the third and last part of the thesis. It is possible to create many morphologies by using immiscible blends and exposing them to different flow and shear conditions. Among others, a three-layer structure was created with a fibrous center and a dispersed elongate outer morphology.
Original languageEnglish
Place of PublicationKgs. Lyngby
PublisherTechnical University of Denmark
Number of pages239
ISBN (Electronic)978-87-7475-770-2
Publication statusPublished - 2024
SeriesDCAMM Special Report
NumberS343
ISSN0903-1685

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  • Compounding of Smart Materials

    Grønborg, F. (PhD Student), Pedersen, D. B. (Main Supervisor), Daugaard, A. E. (Supervisor), Spangenberg, J. (Supervisor), Kjelgaard Vedel-Smith, N. (Examiner), Petersen, S. (Examiner) & Rønsholt, L. (Supervisor)

    01/02/202014/01/2025

    Project: PhD

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