but.committee	prof. Ing. Jiří Švejcar, CSc. (předseda) Prof. Dr.-Ing. habil. Aldo R. Boccaccini (člen) prof. RNDr. Michal Kotoul, DrSc. (člen) prof. Dr. Dipl.-Min. Willi Pabst (člen) prof. RNDr. Jan Kohout, CSc. (člen) prof. Ing. Martin Trunec, Dr. (člen) Ing. Zdeněk Chlup, Ph.D. (člen)	cs
but.defence	Dosažené výsledky, jejich prezentace, reakce na připomínky oponentů i obecná diskuse jednoznačně prokázaly připravenost doktoranda pro tvůrčí práci. Práce je vysoce inovativní a přinesla řadu originálních výsledků a poznatků, např. použití mikrofibril celulózy na zpevnění polymerních povlaků, objasnění experimentálního i teoretického vlivu polymerního a kompozitního povlaku na zpevnění struktury a lomové chování keramické pěny, změny ve struktuře bioskla, ke kterým dochází v průběhu SPS. Práce přinesla řadu námětů k využití poznatků a dalšímu pokračování.	cs
but.jazyk	angličtina (English)
but.program	Fyzikální a materiálové inženýrství	cs
but.result	práce byla úspěšně obhájena	cs
dc.contributor.advisor	Dlouhý, Ivo	en
dc.contributor.author	Bertolla, Luca	en
dc.contributor.referee	Prof. Dr.-Ing. habil. Aldo R. Boccaccini	en
dc.contributor.referee	Kotoul, Michal	en
dc.contributor.referee	Pabst, Willi	en
dc.date.created	2015	cs
dc.description.abstract	Bioactive glasses exhibit unique characteristics as a material for bone tissue engineering. Unfortunately, their extensive application for the repair of load-bearing bone defects is still limited by low mechanical strength and fracture toughness. The main aim of this work was two-fold: the reinforcement of brittle Bioglass®-based porous scaffolds and the production of bulk Bioglass® samples exhibiting enhanced mechanical properties. For the first task, scaffolds were coated by composite coating constituted by polyvinyl alcohol (PVA) and microfibrillated cellulose (MFC). The addition of PVA/MFC coating led to a 10 fold increase of compressive strength and a 20 fold increase of tensile strength in comparison with non-coated scaffolds. SEM observations of broken struts surfaces proved the reinforcing and toughening mechanism of the composite coating which was ascribed to crack bridging and fracture of cellulose fibrils. The mechanical properties of the coating material were investigated by tensile testing of PVA/MFC stand–alone specimens. The stirring time of the PVA/MFC solution came out as a crucial parameter in order to achieve a more homogeneous dispersion of the fibres and consequently enhanced strength and stiffness. Numerical simulation of a PVA coated Bioglass® strut revealed the infiltration depth of the coating until the crack tip as the most effective criterion for the struts strengthening. Contact angle and linear viscosity measurements of PVA/MFC solutions showed that MFC causes a reduction in contact angle and a drastic increase in viscosity, indicating that a balance between these opposing effects must be achieved. Concerning the production of bulk samples, conventional furnace and spark plasma sintering technique was used. Spark plasma sintering performed without the assistance of mechanical pressure and at heating rates ranging from 100 to 300°C /min led to a material having density close to theoretical one and fracture toughness nearly 4 times higher in comparison with conventional sintering. Fractographic analysis revealed the crack deflection as the main toughening mechanisms acting in the bulk Bioglass®. Time–dependent crack healing process was also observed. The further investigation on the non-equilibrium phases crystallized is required. All obtained results are discussed in detail and general recommendations for scaffolds with enhanced mechanical resistance are served.	en
dc.description.abstract	Bioactive glasses exhibit unique characteristics as a material for bone tissue engineering. Unfortunately, their extensive application for the repair of load-bearing bone defects is still limited by low mechanical strength and fracture toughness. The main aim of this work was two-fold: the reinforcement of brittle Bioglass®-based porous scaffolds and the production of bulk Bioglass® samples exhibiting enhanced mechanical properties. For the first task, scaffolds were coated by composite coating constituted by polyvinyl alcohol (PVA) and microfibrillated cellulose (MFC). The addition of PVA/MFC coating led to a 10 fold increase of compressive strength and a 20 fold increase of tensile strength in comparison with non-coated scaffolds. SEM observations of broken struts surfaces proved the reinforcing and toughening mechanism of the composite coating which was ascribed to crack bridging and fracture of cellulose fibrils. The mechanical properties of the coating material were investigated by tensile testing of PVA/MFC stand–alone specimens. The stirring time of the PVA/MFC solution came out as a crucial parameter in order to achieve a more homogeneous dispersion of the fibres and consequently enhanced strength and stiffness. Numerical simulation of a PVA coated Bioglass® strut revealed the infiltration depth of the coating until the crack tip as the most effective criterion for the struts strengthening. Contact angle and linear viscosity measurements of PVA/MFC solutions showed that MFC causes a reduction in contact angle and a drastic increase in viscosity, indicating that a balance between these opposing effects must be achieved. Concerning the production of bulk samples, conventional furnace and spark plasma sintering technique was used. Spark plasma sintering performed without the assistance of mechanical pressure and at heating rates ranging from 100 to 300°C /min led to a material having density close to theoretical one and fracture toughness nearly 4 times higher in comparison with conventional sintering. Fractographic analysis revealed the crack deflection as the main toughening mechanisms acting in the bulk Bioglass®. Time–dependent crack healing process was also observed. The further investigation on the non-equilibrium phases crystallized is required. All obtained results are discussed in detail and general recommendations for scaffolds with enhanced mechanical resistance are served.	cs
dc.description.mark	P	cs
dc.identifier.citation	BERTOLLA, L. Mechanical Reinforcement of Bioglass®-Based Scaffolds [online]. Brno: Vysoké učení technické v Brně. Fakulta strojního inženýrství. 2015.	cs
dc.identifier.other	89494	cs
dc.identifier.uri	http://hdl.handle.net/11012/51852
dc.language.iso	en	cs
dc.publisher	Vysoké učení technické v Brně. Fakulta strojního inženýrství	cs
dc.rights	Standardní licenční smlouva - přístup k plnému textu bez omezení	cs
dc.subject	bioactive glass	en
dc.subject	scaffolds	en
dc.subject	composite material	en
dc.subject	mechanical properties	en
dc.subject	tensile test	en
dc.subject	SPS	en
dc.subject	bioactive glass	cs
dc.subject	scaffolds	cs
dc.subject	composite material	cs
dc.subject	mechanical properties	cs
dc.subject	tensile test	cs
dc.subject	SPS	cs
dc.title	Mechanical Reinforcement of Bioglass®-Based Scaffolds	en
dc.title.alternative	Mechanical Reinforcement of Bioglass®-Based Scaffolds	cs
dc.type	Text	cs
dc.type.driver	doctoralThesis	en
dc.type.evskp	dizertační práce	cs
dcterms.dateAccepted	2015-12-10	cs
dcterms.modified	2015-12-15-09:33:15	cs
eprints.affiliatedInstitution.faculty	Fakulta strojního inženýrství	cs
sync.item.dbid	89494	en
sync.item.dbtype	ZP	en
sync.item.insts	2025.03.27 14:41:41	en
sync.item.modts	2025.01.15 15:07:43	en
thesis.discipline	Fyzikální a materiálové inženýrství	cs
thesis.grantor	Vysoké učení technické v Brně. Fakulta strojního inženýrství. Ústav materiálových věd a inženýrství	cs
thesis.level	Doktorský	cs
thesis.name	Ph.D.	cs

Mechanical Reinforcement of Bioglass®-Based Scaffolds

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