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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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The study of using lactic acid esters for preparing lactides and PLA
Vida, Mikuláš ; Figalla, Silvestr (referee) ; Petrůj, Jaroslav (advisor)
This diploma thesis deals with use of lactic acid esters for preparation of lactides and PLA. In the theoretical part, it has been processed literature review focus on manufacturing technologies and properties of lactic acid and its esters (especially ethyl ester and lactides). In the experimental part, it has been designed and realized functional laboratory apparatus for preparation of cyclic dimer of lactic acid – lactides. On this apparatus, there were carried out principal laboratory experiments leading to optimization of lactides yields using various catalysts.
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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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Geopolymers Incorporating Wastes and Composites Processing
Taveri, Gianmarco ; Perná,, Ivana (referee) ; Pouchlý, Václav (referee) ; Dlouhý, Ivo (advisor)
Buildings construction and realization of public infrastructures have always been a primary need in the human society, developing low cost and user-friendly materials which also encounter safety and durability requirements. Portland cement is the most used material in construction industry from the industrial revolution up to date, but the raising concerns related to the climate change are pushing the governments worldwide to replace it with more eco-friendly and greener materials. Geopolymers are considered to be best alternatives to Portland cement in construction industry, but issues related to cost and mechanical properties are still hindering the commercialization of this material. Geopolymer incorporating wastes is one of the solutions. Fly ash, a thermal power plant by-product, and borosilicate glass, a recycled glass from pharmaceutical vials, are suitable candidates in geopolymers activation. NMR and FTIR spectroscopies demonstrated that borates from borosilicate glass are active compounds in geopolymerization, substituting the alumina is its role, composing a B-Al-Si network never observed before. Various fly ash and borosilicate glass weight contents were studied in terms of mechanical properties (compression test, 3-point bending test). It was found that fly ash 55 wt.% and borosilicate 45 wt.% composition activated in 13 M NaOH solution holds the best compressive and flexural strength (45 and 4 MPa respectively), 25% stronger than similar counterparts found in literature. Cellulose fibres in different weight contents were dispersed into the geopolymeric paste to produce geopolymer composites, with the aim to render the material more suitable for structural applications. 3-point bending test showed an improvement of the flexural strength of about 165% (12 MPa), while the chevron notch method displayed a fracture toughness of 0.7 MPam1/2, in line with the results of geopolymer composites found in literature. In this thesis work, fly ash was also successfully densified in 3 M NaOH solution and distilled water through a new method based on hydraulic pressure, called hydro-pressure sintering. This innovative technology involves a drastic reduction of NaOH utilization in geopolymerization, rendering the material more eco-friendly. XRD spectroscopy conducted on produced samples revealed a higher formation of crystals, most likely induced by the application of hydraulic pressure (450 MPa).
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Geopolymers Incorporating Wastes and Composites Processing
Taveri, Gianmarco ; Perná,, Ivana (referee) ; Pouchlý, Václav (referee) ; Dlouhý, Ivo (advisor)
Buildings construction and realization of public infrastructures have always been a primary need in the human society, developing low cost and user-friendly materials which also encounter safety and durability requirements. Portland cement is the most used material in construction industry from the industrial revolution up to date, but the raising concerns related to the climate change are pushing the governments worldwide to replace it with more eco-friendly and greener materials. Geopolymers are considered to be best alternatives to Portland cement in construction industry, but issues related to cost and mechanical properties are still hindering the commercialization of this material. Geopolymer incorporating wastes is one of the solutions. Fly ash, a thermal power plant by-product, and borosilicate glass, a recycled glass from pharmaceutical vials, are suitable candidates in geopolymers activation. NMR and FTIR spectroscopies demonstrated that borates from borosilicate glass are active compounds in geopolymerization, substituting the alumina is its role, composing a B-Al-Si network never observed before. Various fly ash and borosilicate glass weight contents were studied in terms of mechanical properties (compression test, 3-point bending test). It was found that fly ash 55 wt.% and borosilicate 45 wt.% composition activated in 13 M NaOH solution holds the best compressive and flexural strength (45 and 4 MPa respectively), 25% stronger than similar counterparts found in literature. Cellulose fibres in different weight contents were dispersed into the geopolymeric paste to produce geopolymer composites, with the aim to render the material more suitable for structural applications. 3-point bending test showed an improvement of the flexural strength of about 165% (12 MPa), while the chevron notch method displayed a fracture toughness of 0.7 MPam1/2, in line with the results of geopolymer composites found in literature. In this thesis work, fly ash was also successfully densified in 3 M NaOH solution and distilled water through a new method based on hydraulic pressure, called hydro-pressure sintering. This innovative technology involves a drastic reduction of NaOH utilization in geopolymerization, rendering the material more eco-friendly. XRD spectroscopy conducted on produced samples revealed a higher formation of crystals, most likely induced by the application of hydraulic pressure (450 MPa).
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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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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.
|
|
|
The study of using lactic acid esters for preparing lactides and PLA
Vida, Mikuláš ; Figalla, Silvestr (referee) ; Petrůj, Jaroslav (advisor)
This diploma thesis deals with use of lactic acid esters for preparation of lactides and PLA. In the theoretical part, it has been processed literature review focus on manufacturing technologies and properties of lactic acid and its esters (especially ethyl ester and lactides). In the experimental part, it has been designed and realized functional laboratory apparatus for preparation of cyclic dimer of lactic acid – lactides. On this apparatus, there were carried out principal laboratory experiments leading to optimization of lactides yields using various catalysts.
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