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Polycaprolactone, synthesis, characterization, and degradability
Boháčová, Zdeňka ; Vojtová, Lucy (referee) ; Hermanová, Soňa (advisor)
Presented diploma thesis deals with the study of ring-opening polymerization (ROP) of caprolactone catalyzed by novel organic and organometallic compounds. In the theoretical part of the thesis a summary of polymerization strategies and catalytic/initiators systems for ROP of polyesters is overviewed on the basis of reported background research. In experimental part a series of caprolactone polymerization runs with the view of polymerization conditions (solution/monomer ratio, catalyst/initiator ratio, monomer/initiator ratio and monomer concentration) at the temperature range of 25-70 °C was carried out. The experimental study was focused on catalytic precursors based on organic carbenes (tBuNCH=CHN+tBu)CH Cl- (NHC-tBu) in tetrahydrofuran solution and complex of aluminium{O,O’-[4,5-P(O)Ph2tz]-AlMe2} Ph = phenyl, tz = triazole, (OAlMe2) in chlorobenzene solution. Obtained polymers were precisely characterized by means of 1H NMR spectroscopy (Bruker Avance), Differential scanning calorimetry (TA Instruments Q 2000) and Gel permeation chromatography (Agilent Technologies 1100 series) methods. The microbial degradability of synthesized polymer sample having Mn = 12 kg/mol, Mw/Mn = 2.5 and crystallinity degree of 53 % was examined. The polymer in the form of melt-pressed films and powder form was bacterially aged in Bacillus subtilis (BS) strain inoculated mineral and nutrient media for 42 days. Scanning electron microscopy (SEM) and Confocal laser scanning microscopy (CLSM) confirmed the crack development on the surface of films as the consequence of microbial attack in comparison with unchanged control samples. Moreover, the pink coloration of polymer suspension was observed as the consequence of bacterial activity.
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Polymerization of Lactides in the Melt
Horkel, Ondřej ; Tomala, Libor (referee) ; Petrůj, Jaroslav (advisor)
This bachelor thesis deals with the problematics of Lactide polymerization in the melt. Theoretical part summarizes properties of lactic acid, lactides and polylactides as well as currently used methods of their preparation. In experimental part, a set of three experiments was designed, namely dependance of viscosity average molecular weight on catalyst concentration, polymerisation temperature and polymerisation time. This was achieved by measuring cinematic viscosity using Ubbelohde viscosimeter. As a result of these experiments, it was found that one of posssible combinations of conditions resulting in high molecular weight polymers is the following: concentration ratio of catalyst towards lactide 110–4, polymerisation teperature 160 °C and polymerisation time 3 hours.
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Algorithms for forward and backward planning
Sluka, Filip ; Hromková, Ivana (referee) ; Simeonov, Simeon (advisor)
The thesis deals with production planning. It contains theoretical description of methods used for production planning and optimizing. Thesis describes bottleneck problems in production. It offers overview of ways to identify and analyze bottleneck influence to manufacturing process efficiency. Thesis proposes ways to eliminate bottlenecks using various algorithm types. It applies theoretical knowledges from optimization and graph theory to program creation that is focused on order delay and readjustment time minimizing. The program implements genetic algorithm.
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The Polymerization and Copolymerization of e-caprolactone using Organic and Organometallic Catalysts
Smrčková, Markéta ; Vojtová, Lucy (referee) ; Hermanová, Soňa (advisor)
Aliphatic polyesters due to their both biodegradability and biocompatibility appear as a class of promising candidates for biomaterials. Nevertheless, their utilization in practical biomedical systems relies on reproducible synthesis of defined products with the absence of residual toxics giving rise to undesired immunological response in human host. The literature review aim at reporting on the initiators/catalytic systems and synthetic strategies of polycaprolactone preparation. The experimental objective of this work was to verify the presence of catalytic residues based on organic carbenes and organometallic complexes of aluminium in prepared polyesters. A series of polycaprolactone (PCL) samples was purified by re-precipitation in methanol at -10 °C. The presence of catalytic residues in PCL after each purification step was monitored by 1H NMR (Bruker Avance). The residual amount of aluminium was determined by means of Atomic Absorption Spectrometry (AAS) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS).
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PLA Synthesis in Solution
Svítil, Jan ; Zdeněk, Přikryl (referee) ; Petrůj, Jaroslav (advisor)
This thesis is studying PLA syntheses using polymerization of lactides in solution. Theoretical part deals with properties and production of lactic acid, lactides and polylactides. In the experimental part, possibilities of lactides polymerization in solution has been summerised and verified. Syntheses were performed via “solvothermal” method using 7 solvents (toluene, chloroforme, 1,2-chlorobenzene, acetone, tetrahydrofurane, cyclohexane and hexane). Using hexane as solvent, at concentration ratio catalyzer/lactide 1 : 1 000, polymerization temperature 160 °C and reaction time 20 h, polylactide of viscosity average molecular weight 179 000 gmol–1 was synthetized from the lactide.
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Algorithms for forward and backward planning
Sluka, Filip ; Hromková, Ivana (referee) ; Simeonov, Simeon (advisor)
The thesis deals with production planning. It contains theoretical description of methods used for production planning and optimizing. Thesis describes bottleneck problems in production. It offers overview of ways to identify and analyze bottleneck influence to manufacturing process efficiency. Thesis proposes ways to eliminate bottlenecks using various algorithm types. It applies theoretical knowledges from optimization and graph theory to program creation that is focused on order delay and readjustment time minimizing. The program implements genetic algorithm.
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|
|
Polymerization of Lactides in the Melt
Horkel, Ondřej ; Tomala, Libor (referee) ; Petrůj, Jaroslav (advisor)
This bachelor thesis deals with the problematics of Lactide polymerization in the melt. Theoretical part summarizes properties of lactic acid, lactides and polylactides as well as currently used methods of their preparation. In experimental part, a set of three experiments was designed, namely dependance of viscosity average molecular weight on catalyst concentration, polymerisation temperature and polymerisation time. This was achieved by measuring cinematic viscosity using Ubbelohde viscosimeter. As a result of these experiments, it was found that one of posssible combinations of conditions resulting in high molecular weight polymers is the following: concentration ratio of catalyst towards lactide 110–4, polymerisation teperature 160 °C and polymerisation time 3 hours.
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|
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PLA Synthesis in Solution
Svítil, Jan ; Zdeněk, Přikryl (referee) ; Petrůj, Jaroslav (advisor)
This thesis is studying PLA syntheses using polymerization of lactides in solution. Theoretical part deals with properties and production of lactic acid, lactides and polylactides. In the experimental part, possibilities of lactides polymerization in solution has been summerised and verified. Syntheses were performed via “solvothermal” method using 7 solvents (toluene, chloroforme, 1,2-chlorobenzene, acetone, tetrahydrofurane, cyclohexane and hexane). Using hexane as solvent, at concentration ratio catalyzer/lactide 1 : 1 000, polymerization temperature 160 °C and reaction time 20 h, polylactide of viscosity average molecular weight 179 000 gmol–1 was synthetized from the lactide.
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Polycaprolactone, synthesis, characterization, and degradability
Boháčová, Zdeňka ; Vojtová, Lucy (referee) ; Hermanová, Soňa (advisor)
Presented diploma thesis deals with the study of ring-opening polymerization (ROP) of caprolactone catalyzed by novel organic and organometallic compounds. In the theoretical part of the thesis a summary of polymerization strategies and catalytic/initiators systems for ROP of polyesters is overviewed on the basis of reported background research. In experimental part a series of caprolactone polymerization runs with the view of polymerization conditions (solution/monomer ratio, catalyst/initiator ratio, monomer/initiator ratio and monomer concentration) at the temperature range of 25-70 °C was carried out. The experimental study was focused on catalytic precursors based on organic carbenes (tBuNCH=CHN+tBu)CH Cl- (NHC-tBu) in tetrahydrofuran solution and complex of aluminium{O,O’-[4,5-P(O)Ph2tz]-AlMe2} Ph = phenyl, tz = triazole, (OAlMe2) in chlorobenzene solution. Obtained polymers were precisely characterized by means of 1H NMR spectroscopy (Bruker Avance), Differential scanning calorimetry (TA Instruments Q 2000) and Gel permeation chromatography (Agilent Technologies 1100 series) methods. The microbial degradability of synthesized polymer sample having Mn = 12 kg/mol, Mw/Mn = 2.5 and crystallinity degree of 53 % was examined. The polymer in the form of melt-pressed films and powder form was bacterially aged in Bacillus subtilis (BS) strain inoculated mineral and nutrient media for 42 days. Scanning electron microscopy (SEM) and Confocal laser scanning microscopy (CLSM) confirmed the crack development on the surface of films as the consequence of microbial attack in comparison with unchanged control samples. Moreover, the pink coloration of polymer suspension was observed as the consequence of bacterial activity.
|
|
|
The Polymerization and Copolymerization of e-caprolactone using Organic and Organometallic Catalysts
Smrčková, Markéta ; Vojtová, Lucy (referee) ; Hermanová, Soňa (advisor)
Aliphatic polyesters due to their both biodegradability and biocompatibility appear as a class of promising candidates for biomaterials. Nevertheless, their utilization in practical biomedical systems relies on reproducible synthesis of defined products with the absence of residual toxics giving rise to undesired immunological response in human host. The literature review aim at reporting on the initiators/catalytic systems and synthetic strategies of polycaprolactone preparation. The experimental objective of this work was to verify the presence of catalytic residues based on organic carbenes and organometallic complexes of aluminium in prepared polyesters. A series of polycaprolactone (PCL) samples was purified by re-precipitation in methanol at -10 °C. The presence of catalytic residues in PCL after each purification step was monitored by 1H NMR (Bruker Avance). The residual amount of aluminium was determined by means of Atomic Absorption Spectrometry (AAS) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS).
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