Matching Items (2)
Filtering by
- All Subjects: Separations
- All Subjects: synthetic cartilage replacements
- Creators: Green, Matthew D.
- Member of: Barrett, The Honors College Thesis/Creative Project Collection
- Resource Type: Text
Description
This study details the construction and operation of a dry-jet wet spinning apparatus for extruding hollow fiber membranes (HFMs). The main components of the apparatus are a spinneret, a coagulation bath, and an automatic collection reel. Continuous fiber formation was achieved using two syringe pumps simultaneously delivering polymer dope and bore fluid to the spinneret. Based on apparatus runs performed with Polysulfone (PSF) dopes dissolved in N,N-Dimethylacetamide and supporting rheological analysis, the entanglement concentration, ce, was identified as a minimum processing threshold for creating HFMs. Similarly, significant increases in the ultimate tensile strength, fracture strain, and Young's modulus for extruded HFMs were observed as polymer dope concentration was increased at levels near ce. Beyond this initial increase, subsequent tests at higher PSF concentrations yielded diminishing changes in mechanical properties, suggesting an asymptotic approach to a point where the trend would cease. Without further research, it is theorized that this point falls on a transition from the semidiute entangled to concentrated concentration regimes. SEM imaging of samples revealed the formation of grooved structures on the inner surface of samples, which was determined to be a result of the low flowrate and polymer dope concentrations used in processing the HFMs during apparatus runs. Based on continued operation of the preliminary apparatus design, many areas of improvement were noted. Namely, these consisted of controlling the collector speed, eliminating rubbing of nascent fibers against the edge of the coagulation bath by installing an elevated roller, and replacing tygon tubing for the polymer line with a luer lock adapter for direct syringe attachment to the spinneret.
ContributorsBridge, Alexander Thomas (Author) / Green, Matthew D. (Thesis director) / Lin, Jerry Y. S. (Committee member) / School of Mathematical and Statistical Sciences (Contributor) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
Photocurable nanocomposites have great potential within advanced manufacturing, multifunctional materials, and most specifically tissue engineering. The properties and characteristics of these nanocomposites can be tailored to mimic those of various tissues and/or cartilage, allowing the bio-inspired synthetic materials to replace them. This project investigates the effect of methacrylate-functionalized (MA-SiO2) and vinyl-functionalized (V-SiO2) silica nanoparticle loading content on the thermal, mechanical, physical, and morphological characteristics of PEG nanocomposites. It was discovered that both V-SiO2 and MA-SiO2 did not considerably impact the glass-transition temperature or hydrophilicity of the material. The gel fraction of composites containing V-SiO2 decreases with the initial addition of 3.8 wt%, but then displays an increase with further addition (>7.4 wt%) until it reaches a plateau at 10.7 wt%. Whereas, the MA-SiO2 induced no significant changes in gel fraction with increased loading. An increase in mechanical properties was also observed with increasing concentration for both sets of series. However, due to the higher crosslink density, MA-SiO2 reached its ultimate mechanical stress threshold at a lower concentration of 7.4 wt%, while V-SiO2 maxed out at 10.7 wt%. Scanning electron microscopy coupled with transmission electron microscopy revealed that V-SiO2 displayed a bimodal size distribution, while MA-SiO2 displayed only one.
ContributorsHocken, Alexis (Co-author, Co-author) / Green, Matthew D. (Thesis director) / Holloway, Julianne L. (Committee member) / Olsen, Bradley D. (Committee member) / School of Molecular Sciences (Contributor) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05