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Hierarchical porosity in additively manufactured bioengineering scaffolds: fabrication & characterisation

Hierarchical porosity in additively manufactured bioengineering scaffolds: fabrication & characterisation
Hierarchical porosity in additively manufactured bioengineering scaffolds: fabrication & characterisation
Biomedical scaffolds with a high degree of porosity are known to facilitate the growth of healthy functioning tissues. In this study, scaffolds with hierarchi cal porosity are manufactured and their mechanical and thermal properties are characterised. Multi-scale porosity is achieved in scaffolds fabricated by fused deposition modelling in a novel way. Random intrinsic porosity at micron length scale obtained from particulate leaching is combined with the structured extrinsic porosity at millimeter length scales afforded by controlling the spacing between filaments. Polylactic acid (PLA) is blended with Polyvinyl alcohol (PVA) and an inorganic sacrificial phase, sodium chloride (NaCl), to produce pores at length scales of up to two orders of magnitude smaller than the inter-filament voids within 3D printed lattices. The specific elastic modulus and specific strength are maximised by optimising the polymer blends. The porosity level and pore size distribution of the foamy filaments within lattices are quantified statistically. Compression tests are performed on the porous samples and their mechanical response is attributed to their microstructure and density using cellular solid models that possess power law dependence associated with various elastic deformation mechanisms of cell walls. The relationship between pore architecture, pore connectivity, the blend material composition, and mechanical response of produced foams is brought out. Foams obtained using the PLA:PVA:NaCl 42%-18% 40% material blends show relatively high specific elastic modulus, specific strength and strain at failure. A quadratic power law relating the Young’s modulus with the relative density is experimentally obtained, which is consistent with theoretical models for open-cell foams. 3D printing with blends, followed by leaching, produces structures with cumulative intrinsic and extrinsic porosity as high as 80%, in addition to good mechanical integrity.
3D printing, Hierarchical porosity, biomedical scaffold, cellular solid models, open-cell foams, particulate leaching
1751-6161
1-12
Shalchy, Faezeh
b5c031f1-ccd4-4a41-b592-faeb0c8b9c69
Lovell, Christopher James
e894d207-d2e7-4bb3-b39d-ea62f204140c
Bhaskar, Atul
d4122e7c-5bf3-415f-9846-5b0fed645f3e
Shalchy, Faezeh
b5c031f1-ccd4-4a41-b592-faeb0c8b9c69
Lovell, Christopher James
e894d207-d2e7-4bb3-b39d-ea62f204140c
Bhaskar, Atul
d4122e7c-5bf3-415f-9846-5b0fed645f3e

Shalchy, Faezeh, Lovell, Christopher James and Bhaskar, Atul (2020) Hierarchical porosity in additively manufactured bioengineering scaffolds: fabrication & characterisation. Journal of the Mechanical Behavior of Biomedical Materials, 110, 1-12, [103968]. (doi:10.1016/j.jmbbm.2020.103968).

Record type: Article

Abstract

Biomedical scaffolds with a high degree of porosity are known to facilitate the growth of healthy functioning tissues. In this study, scaffolds with hierarchi cal porosity are manufactured and their mechanical and thermal properties are characterised. Multi-scale porosity is achieved in scaffolds fabricated by fused deposition modelling in a novel way. Random intrinsic porosity at micron length scale obtained from particulate leaching is combined with the structured extrinsic porosity at millimeter length scales afforded by controlling the spacing between filaments. Polylactic acid (PLA) is blended with Polyvinyl alcohol (PVA) and an inorganic sacrificial phase, sodium chloride (NaCl), to produce pores at length scales of up to two orders of magnitude smaller than the inter-filament voids within 3D printed lattices. The specific elastic modulus and specific strength are maximised by optimising the polymer blends. The porosity level and pore size distribution of the foamy filaments within lattices are quantified statistically. Compression tests are performed on the porous samples and their mechanical response is attributed to their microstructure and density using cellular solid models that possess power law dependence associated with various elastic deformation mechanisms of cell walls. The relationship between pore architecture, pore connectivity, the blend material composition, and mechanical response of produced foams is brought out. Foams obtained using the PLA:PVA:NaCl 42%-18% 40% material blends show relatively high specific elastic modulus, specific strength and strain at failure. A quadratic power law relating the Young’s modulus with the relative density is experimentally obtained, which is consistent with theoretical models for open-cell foams. 3D printing with blends, followed by leaching, produces structures with cumulative intrinsic and extrinsic porosity as high as 80%, in addition to good mechanical integrity.

Text
FaezehShalchyPaper - Accepted Manuscript
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More information

Accepted/In Press date: 30 June 2020
e-pub ahead of print date: 10 July 2020
Published date: October 2020
Keywords: 3D printing, Hierarchical porosity, biomedical scaffold, cellular solid models, open-cell foams, particulate leaching

Identifiers

Local EPrints ID: 442455
URI: http://eprints.soton.ac.uk/id/eprint/442455
ISSN: 1751-6161
PURE UUID: ff7e64fb-426a-458f-8598-b1c955ac7b08

Catalogue record

Date deposited: 15 Jul 2020 16:32
Last modified: 25 Nov 2021 23:04

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Contributors

Author: Faezeh Shalchy
Author: Christopher James Lovell
Author: Atul Bhaskar

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