Mulky, Elias Tarek Constantin (2022). Engineering Absorbable Fiber Reinforced Bone Substitute Materials. (Thesis). Universität Bern, Bern
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Abstract
The aim of this thesis, embedded in the clinically relevant field of absorbable bone substitute materials, specifically calcium phosphate cements reinforced with poly-l-lactic-acid fibers, was to investigate the factors influencing the compressive strength of these cements and to develop novel methods to improve their mechanical properties. These investigations were grouped into work packages (WP). The first WP examined the dispersibility of the fibers within the cement matrix. Here, a novel method based on particle-assisted sonication was developed to cut, disperse, and mix the fibers together with the cement precursor to manufacture a homogeneous composite. Using this method, a four-fold reinforcement in compressive strength was achieved, compared to pristine cement samples. This method formed a basis for the subsequent WP. The second WP was a systematic screening of the factors influencing the compressive strength and composition of the cement. The factors considered were fiber volume fraction, fiber diameter, and fiber dispersity. The latter was investigated using a novel method developed to determine the fiber density in the fracture area. Fiber dispersity was found to be the main contributing factor for composite reinforcement, resulting in a three-fold increase in compressive strength compared to cement samples reinforced with undispersed fiber meshes. The final WP was a systematic investigation of the fiber-matrix interfacial properties by comparing plasma coating, a widely used method to reduce the contact angle of materials to a calcium-chelating functional coating. This coating resulted in 50% increase in adsorption of barium as exemplary divalent species compared to the control group, and in a two-fold increase in interfacial stiffness, compared to the control group. These results form a systematic study of the factors influencing the mechanical properties of fiber-reinforced bone cements and enable further optimizations to be investigated in this area.
| Item Type: | Thesis |
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| Dissertation Type: | Cumulative |
| Date of Defense: | 23 August 2022 |
| Subjects: | 600 Technology > 610 Medicine & health 600 Technology > 620 Engineering |
| Institute / Center: | 08 Faculty of Science |
| Depositing User: | Hammer Igor |
| Date Deposited: | 21 May 2024 16:35 |
| Last Modified: | 27 May 2024 13:04 |
| URI: | https://boristheses.unibe.ch/id/eprint/5070 |
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