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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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New Processes of Lactid Acid Polymers Preparation
Figalla, Silvestr ; Svěrák, Tomáš (referee) ; Herink,, Tomáš (referee) ; Petrůj, Jaroslav (advisor)
The work focuses on new processes for the preparation of lactic acid derivatives. The main objective was to verify the feasibility of preparing high molecular weight polylactide using ethyl lactate as a precursor of lactide synthesis. Part of the work is devoted to the new ethyl lactate synthesis method. The experimental part of the thesis is divided into partial key steps on the way from the lactic acid to the high molecular polylactide. The preparation of anhydrous ethyl ester of lactic acid (EtLA) was solved in an innovative way using alcoholysis of the oligomeric lactic acid. A kinetic model for isothermal alcoholysis and equimolar reactants ratio was derived from this method. The ethyl lactate was oligomerized by transesterification into the low and high molecular weight oligomer with the help of newly found catalysts suitable for the reaction medium. Stannous lactate was used as catalyst for oligomerization of the low molecular weight polymer suitable for the preparation of lactide (Mn 1000 g.mol-1). Experimental polymerization of ethyl lactate into high molecular weight product in tens of kDa has been investigated with newly synthesized tetraethyllactoyl titanate, Ti(EtLA)4. The laboratory method was derived for the depolymerization of the oligomer into lactide. Optimal conditions found for lactidation are as follow: temperature 225 ° C, pressure 2 kPa, catalysis 0,05 mol% of stannous lactate (with respect to oligomer lactate units). The prepared lactide was refined to polymer grade purity by distillation and subsequent recrystallization from ethyl acetate and toluene. The method for the preparation of high molecular weight PLA through ROP polymerization of lactide has been optimized. By optimization, suitable catalyst concentration was found in combination with the polymerization temperature and the polymerization length. An equimolar mixture of Tin 2-ethylhexanoate and 1-decanol was used as the catalytic system. The optimal ROP conditions for achieving the maximum molecular weight and suppressed polymer coloration (yellowing) are: catalyst concentration 0,01 mol%, temperature 160 °C, and polymerization length 4 hours. PLA with molecular weight Mw= 447 ± 7,8 kg.mol-1 was prepared at these conditions and good repeatability of the result was achieved. The effect of naturally occurring lactide contaminants and their influence on the course and ROP result was experimentally verified on the optimized polymerization system. The purpose was to explore the effect of lactide contamination with water and ethanol as natural lactide contaminants. The results clearly confirm the orderly lower sensitivity of the polymerization system for the presence of ethanol as compared to water contamination. In the case of the presence of water, the course and the result of the polymerization in terms of both the conversion and achieved molecular weights are negatively affected, even when the water content is in the order of 0,001%. Conversely, the presence of ethanol has a positive effect on lactide conversion and polymer polydispersity. Lactides with an alcohol content of about one-tenth of a percent are suitable to reach molecular weights of PLA similar to commercially available products. This difference shoves a significant advantage in the proposed technology of preparing PLA from ethyl lactate, especially for easier purification of crude lactide into polymer grade purity.
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Preparation of Ethyl 2-acetoxypropanoate
Kučerová, Eliška ; Pospíšilová, Aneta (referee) ; Figalla, Silvestr (advisor)
The bachelor thesis focuses on the preparation of ethyl 2-acetoxypropanoate as a potential nonpolar biosolvent. Selected preparation should provide the highest yield possible. For this purpose, a theoretical review of possible syntheses was developed, with emphasis on syntheses based on acetylation of ethyl lactate. The experimental part of the work then focuses in more detail on the possibility of isolating ethyl 2-acetoxypropanoate from the reaction mixture. Product isolation was verified by fractional distillation and extraction method. In the isolated product, the basic physical properties were determined and the spectrum measured by Fourier transformation infrared spectroscopy. Furthermore, the hydrolytic stability of ethyl 2-acetoxypropanoate was investigated and a series of calorimetric measurements were performed. From these measurements, the effect of reaction temperature on reaction rate and product conversion and the effect of catalyst presence was assessed.
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Preparation of Ethyl 2-acetoxypropanoate
Kučerová, Eliška ; Pospíšilová, Aneta (referee) ; Figalla, Silvestr (advisor)
The bachelor thesis focuses on the preparation of ethyl 2-acetoxypropanoate as a potential nonpolar biosolvent. Selected preparation should provide the highest yield possible. For this purpose, a theoretical review of possible syntheses was developed, with emphasis on syntheses based on acetylation of ethyl lactate. The experimental part of the work then focuses in more detail on the possibility of isolating ethyl 2-acetoxypropanoate from the reaction mixture. Product isolation was verified by fractional distillation and extraction method. In the isolated product, the basic physical properties were determined and the spectrum measured by Fourier transformation infrared spectroscopy. Furthermore, the hydrolytic stability of ethyl 2-acetoxypropanoate was investigated and a series of calorimetric measurements were performed. From these measurements, the effect of reaction temperature on reaction rate and product conversion and the effect of catalyst presence was assessed.
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New Processes of Lactid Acid Polymers Preparation
Figalla, Silvestr ; Svěrák, Tomáš (referee) ; Herink,, Tomáš (referee) ; Petrůj, Jaroslav (advisor)
The work focuses on new processes for the preparation of lactic acid derivatives. The main objective was to verify the feasibility of preparing high molecular weight polylactide using ethyl lactate as a precursor of lactide synthesis. Part of the work is devoted to the new ethyl lactate synthesis method. The experimental part of the thesis is divided into partial key steps on the way from the lactic acid to the high molecular polylactide. The preparation of anhydrous ethyl ester of lactic acid (EtLA) was solved in an innovative way using alcoholysis of the oligomeric lactic acid. A kinetic model for isothermal alcoholysis and equimolar reactants ratio was derived from this method. The ethyl lactate was oligomerized by transesterification into the low and high molecular weight oligomer with the help of newly found catalysts suitable for the reaction medium. Stannous lactate was used as catalyst for oligomerization of the low molecular weight polymer suitable for the preparation of lactide (Mn 1000 g.mol-1). Experimental polymerization of ethyl lactate into high molecular weight product in tens of kDa has been investigated with newly synthesized tetraethyllactoyl titanate, Ti(EtLA)4. The laboratory method was derived for the depolymerization of the oligomer into lactide. Optimal conditions found for lactidation are as follow: temperature 225 ° C, pressure 2 kPa, catalysis 0,05 mol% of stannous lactate (with respect to oligomer lactate units). The prepared lactide was refined to polymer grade purity by distillation and subsequent recrystallization from ethyl acetate and toluene. The method for the preparation of high molecular weight PLA through ROP polymerization of lactide has been optimized. By optimization, suitable catalyst concentration was found in combination with the polymerization temperature and the polymerization length. An equimolar mixture of Tin 2-ethylhexanoate and 1-decanol was used as the catalytic system. The optimal ROP conditions for achieving the maximum molecular weight and suppressed polymer coloration (yellowing) are: catalyst concentration 0,01 mol%, temperature 160 °C, and polymerization length 4 hours. PLA with molecular weight Mw= 447 ± 7,8 kg.mol-1 was prepared at these conditions and good repeatability of the result was achieved. The effect of naturally occurring lactide contaminants and their influence on the course and ROP result was experimentally verified on the optimized polymerization system. The purpose was to explore the effect of lactide contamination with water and ethanol as natural lactide contaminants. The results clearly confirm the orderly lower sensitivity of the polymerization system for the presence of ethanol as compared to water contamination. In the case of the presence of water, the course and the result of the polymerization in terms of both the conversion and achieved molecular weights are negatively affected, even when the water content is in the order of 0,001%. Conversely, the presence of ethanol has a positive effect on lactide conversion and polymer polydispersity. Lactides with an alcohol content of about one-tenth of a percent are suitable to reach molecular weights of PLA similar to commercially available products. This difference shoves a significant advantage in the proposed technology of preparing PLA from ethyl lactate, especially for easier purification of crude lactide into polymer grade purity.
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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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