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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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Novel "green" catalysts for controlled ring-opening polymerization of lactide
Surman, František ; Vojtová, Lucy (referee) ; Hermanová, Soňa (advisor)
Syntéza polylaktidu (PLA) polymerací za otevření kruhu cyklického monomeru (ROP) může být uskutečněna různými způsoby. Literatura uvádí více než 100 katalytických systémů, jejichž pomocí lze polylaktid a jiné biodegradabilní alifatické polyestery získat. Například organokovové katalyzátory na bázi Sn, Zn, Al atd. se po splnění své polymerační funkce stávají kontaminanty a pro humánní implantáty je použití takového materiálu diskutabilní. V současné době jsou v centru výzkumné pozornosti nové N-heterocyklické karbenové katalyzátory. Tyto „metal-free“ katalytické struktury jsou schopné reprodukovatelně řídit syntézu polymerů předem definované molekulové hmotnosti s definovanými koncovými skupinami a nízkou polydisperzitou, která je charakteristická pro živý průběh polymerace. Nabízí se možnost syntézy blokových kopolymerů a různorodých makromolekulárních architektur. Předložená diplomová práce se zabývá studiem polymerace cyklického monomeru D,L-laktidu katalyzované N-heterocyklickým karbenem. Polymerace byly vedeny v přítomnosti benzylalkoholu jako iniciátoru v roztoku THF. Byl sledován vliv složení reakčního systému monomer – iniciátor – katalyzátor. Dále byly připraveny polymery opticky čistého L-laktidu s makroiniciátory PEG s Mn = 1000 a 2000 g/mol. Střední číselná molekulová hmotnost (Mn) a polydisperzita (PDI) byly stanoveny pomocí GPC. Definovatelnost koncových skupin vybraných polymerů byla prokázána pomocí 1H NMR.
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Determination of Hydroxyacids including their Low- and High Molecular Derivatives
Lysáková, Klára ; Mravcová, Ludmila (referee) ; Čáslavský, Josef (advisor)
This bachelor thesis deals with the determination of hydroxy acids and their low and high molecular polymers. The theoretical part deals with their properties, production and utilization. The polymers of these substances are used as biodegradable plastics and as absorbable sewing materials. The experimental part is focused on the determination of the total component and on the composition and amount of impurities of selected samples of ethyl lactate, lactides and polylactide. Analysis was performed by gas chromatography (GC) and tandem techniques using GC/MS and Head-Space-GC/MS analysis.
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The Study of Lactides Syntheses from Esters of Lactic Acide
Tomala, Libor ; Chamradová, Ivana (referee) ; Petrůj, Jaroslav (advisor)
This master thesis deals with the synthesis of lactide from lactic acid esters. The theoretical part focuses on the current understanding of technology of lactic acid, its alkyl esters and the cyclic lactic acid dimer - lactide, which is mainly used as a precursor for the synthesis of high moleculat weight biodegradable polylactide (PLA) and other copolymers. Experimental part is then focused on the synthesis of lactide from lactic acid alkyl esters, especially ethyl lactate. Examines the design of a suitable apparatus for this synthesis and the application of the most appropriate reaction conditions (temperature, pressure, catalysis) to optimize the preparation of the desired product. In the end, parameters of prepared lactide are characterized by using of various analytical techniques.
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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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Direct Synthesis of High-Molecular Polymers of Lactic Acid
Mikulík, David ; Kupka, Vojtěch (referee) ; Petrůj, Jaroslav (advisor)
This master thesis deals with the direct synthesis of polymers from lactic acid. The theoretical part focuses on both natural and synthetic ways of production the lactic acid monomer, their advantages and properties. Furthermore, the theoretical part focuses on the synthesis of poly(lactic acid) (PLA) from lactide, and direct polycondensation from lactic acid discussing about influences of catalysts, co-catalysts as well as chain extenders. The experimental part focuses on the synthesis of PLA polymers and co-polymers wherein investigates suitable catalysts, reaction medium for azeotropic dehydration and co-catalyst influence on products. Thermal and analytical analysis of PLA polymers are mentioned at the end of the experimental part.
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Determination of Hydroxyacids including their Low- and High Molecular Derivatives
Lysáková, Klára ; Mravcová, Ludmila (referee) ; Čáslavský, Josef (advisor)
This bachelor thesis deals with the determination of hydroxy acids and their low and high molecular polymers. The theoretical part deals with their properties, production and utilization. The polymers of these substances are used as biodegradable plastics and as absorbable sewing materials. The experimental part is focused on the determination of the total component and on the composition and amount of impurities of selected samples of ethyl lactate, lactides and polylactide. Analysis was performed by gas chromatography (GC) and tandem techniques using GC/MS and Head-Space-GC/MS analysis.
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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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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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Direct Synthesis of High-Molecular Polymers of Lactic Acid
Mikulík, David ; Kupka, Vojtěch (referee) ; Petrůj, Jaroslav (advisor)
This master thesis deals with the direct synthesis of polymers from lactic acid. The theoretical part focuses on both natural and synthetic ways of production the lactic acid monomer, their advantages and properties. Furthermore, the theoretical part focuses on the synthesis of poly(lactic acid) (PLA) from lactide, and direct polycondensation from lactic acid discussing about influences of catalysts, co-catalysts as well as chain extenders. The experimental part focuses on the synthesis of PLA polymers and co-polymers wherein investigates suitable catalysts, reaction medium for azeotropic dehydration and co-catalyst influence on products. Thermal and analytical analysis of PLA polymers are mentioned at the end of the experimental part.
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