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Analysis of biodegradable polymers in soils
Paluchová, Natálie ; Řezáčová, Veronika (referee) ; Kučerík, Jiří (advisor)
Currently, there is a growing interest in usage of biodegradable polymers, regardless of their possible risk of generation of residues. The methods that are used for determination of residues usually include pre-treatment and are expensive and time consuming. Therefore, this bachelor thesis focuses on the development and verification of analytical method that would identify and quantify of biodegradable polymer residues in soils to eliminate the problems arising from sample pre-treatment. Therefore, thermogravimetry, which appears to satisfy the above conditions, was used for the analysis. The area of polymer degradation in three types of soils during thermal oxidation and the effect of polymer on soil during the analysis was investigated. Poly(3 hydroxybutyrate) was chosen to be the representative biodegradable polymer and there were two approaches used to its detection and quatification. The methods were tested for 6 concentrations of poly(3–hydroxybutyrate) (0,1; 0,5; 1; 2; 3; 5 %). The first approach concentrated on the usage of polymer analysis in the presence of a blank (without contaminat), which was subtracted from the blank. Using this method, the temperature interval of polymer degradation and weigh loss changes in this interval were observed. The second method focused on a soil universal model, that allows the identification and quatification of samples when the blank is not present. The blank is simulated by 19 equations, that allow the identification of intervals, in which degradation of samples occurs and also it provides the possibility to determinate the type of the polymer. However, the principle component analysis indicated that the method is sensitive to the type of soil and therefore it needs adjustments. Samples were incubated for 4 months, to verify the sensitivity of the method, in case of partial or complete decomposition of samples by soil microorganisms,. Thereafter, the concentrations of poly(3-hydroxybutryrate) in soil determined by respirometry and thermogravimetry were compared. The results indicated that accelerated degradation caused by poly(3-hydroxybutrylate) or contamination of the sample with the surrounding atmosphere during respiration may have occurred. Residual poly(3–hydroxybutyrate) was thermogravimetrically verified and results were compared to respirometry. According to the results it can be observed that there was an interaction between the soil organic matter and biota or contamination of the sample with the surrounding atmosphere. The results revealed, that there is a possibility of determination of biodegradable polymers in soils by thermogravimetric analysis. There are good results using the blank method, but it is limited by the existence of a blank. The method that is using the soil universal model (without blank) has a great potential in the future, but adjustments still need to be done.
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Biocomposites based on polyhydroxybutyrate for 3D printing
Horálek, Matyáš ; Tocháček, Jiří (referee) ; Přikryl, Radek (advisor)
The submitted diploma thesis deals with preparation and characterization of biocomposite based on poly-3-hydroxybutyrate. Biocomposites were fabricated with respect to later use in 3D printing. The methodology for testing different kinds of materials and their suitability for 3D printing as well as evaluation of mechanical and thermal properties was established. The first part of this work was focused on the experiments with print temperature and the material flow rate and its influence on the look of 3D printed object and on the material tendency to warp during 3D printing. The design of the experiment method was used for the analyzing of obtained data. It was proven that the amount of kaolin and tributyl citrate has positive influence in reducing warping. By optimization of the biocomposite recipe it was achieved improvement in tensile modulus of elasticticity, ductility, tensile strength, notched and unnotched toughness.
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Evaluation of the effects of biodegradable microplastics on biota of freshwater ecosystem via ecotoxicity tests
Procházková, Petra ; Maršálek,, Blahoslav (referee) ; Beklová, Miroslava (referee) ; Zlámalová Gargošová, Helena (advisor)
Microplastics, which are ubiquitous contaminants of freshwater ecosystems, have raised concerns regarding their potential impact on the environment. For this reason, there is an effort to replace conventional plastics with biodegradable alternatives that can easily degrade in the environment. However, the process of biodegradation of these materials requires specific conditions, such as temperature, humidity, pH, and the presence of microorganisms, which are not always met adequately. Consequently, they may fragment and form biodegradable microplastics that can affect the environment similarly to conventional microplastics. Therefore, the aim of this study was to assess the impact of microplastics of biodegradable poly(3-hydroxybutyrate) microplastics on freshwater organisms, specifically the alga Desmodesmus subspicatus, the plant Lemna minor and the crustacean Daphnia magna. Additionally, we aimed to develop a suitable analytical method for the direct detection of microplastics in the body of D. magna. Although the observed effects were not always significant, they highlighted certain secondary problems that may arise due to the presence of biodegradable microplastics in the environment These issues could be related to biodegradability and the formation of biofilm on the surface of biodegradable microplastics, leading to subsequent nutrient depletion in the surrounding environment. Therefore, the use of biodegradable plastics as a substitute for conventional materials must be approached critically.
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Preparation of Poly(3-hydroxybutyrate) based acrylic monomer
Liška, Marek ; Přikryl, Radek (referee) ; Figalla, Silvestr (advisor)
The main aim of this thesis is to research and prepare acrylic (methacrylic) monomers derived from poly(3-hydroxybutyrate). The monomers were prepared in two-step syntheses. In the first step P3HB was depolymerised with selected alcohols and afterwards, products of those syntheses were used as substrate and mixed with polymethylmethacrylate to produce their methacrylic derivates. The selected alcohols for the alcoholysis were ethanol and ethylene glycol. In total, four substances were prepared. Products of alcoholysis were ethyl-3- hydroxybutyrate, 2-hydroxyethyl-3-hydroxybutyrate and their methacrylic derivates. Significant part of this thesis is aimed towards the analysis of prepared substances and the analysis of reactions. In the process, titrations and instrumental methods, such as gel permeation chromatography (GPC), infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), thermogravimetry (TGA) and differential scanning calorimetry (DSC) were used. This work describes preparation and analysis of polymers prepared from methacrylates from the mentioned syntheses. Cross-linked polymers, because of their low glass-transition temperature are elastomers.
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Biopolymer particles based on polyhydroxybutyrate
Gregušková, Zuzana ; Zemanová, Jana (referee) ; Přikryl, Radek (advisor)
This Bachelor´s thesis deals with preparation of abrasive particles from poly(3-hydroxybutyrate) and their optimization for cosmetics usage. It explores morphology of prepared particles and its effect on their abrasive ability. Moreover, it compares abrasive effectiveness of prepared particles with those commercially available. Several types of preparation methods of biopolymer particles such as milling, fibre spinning, pelletisation and solution preparation were carried out and optimized. Prepared particles were analysed using scanning electron microscopy. Semi-automatic system for testing of abrasiveness of prepared particles was made up from basic parts of 3D printing machine. This device was tested and calibrated using floral foam and sandpaper with different grades of granularity and used for comparison of abrasiveness of prepared particles. Mechanical response of particles under pressure was also investigated. It was found out that measured mechanical properties correlate with the data from abrasiveness test. Size and shape of particles, their morphology, mechanical properties and abrasiveness can be controlled depending on the preparation method used. Selected prepared and commercial abrasive particles were applied into prepared cosmetic foundations for peeling with the goal of sensory evaluation of abrasive effectiveness of prepared particles.
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Poly(3-hydroxybutyrate) based materials for 3D printing in medical applications
Krobot, Štěpán ; Vojtová, Lucy (referee) ; Přikryl, Radek (advisor)
Tato diplomová práce se zabývá přípravou a testováním 3D tištěných skafoldů pro kostní tkáňové inženýrství. Cílem práce je laboratorní příprava polymerních směsí na bázi poly(3-hydroxybutyrátu), polymléčné kyseliny a polykaprolaktonu a jejich zpracování do podoby 3D tiskových strun. Byly připraveny tři polymerní směsi, které byly zpracovány do podoby 3D tiskových strun. Pro vyhodnocení termických vlastností byla provedena diferenciální skenovací kalorimetrie, následně teplotní věžový test a test „warpingu“ pro stanovení zpracovatelských podmínek při 3D tisku. Nejnižší naměřený „warping“ koeficient byl 1,26 u směsi poly(3-hydroxybutyrátu) s polykaprolaktonem a změkčovadlem. Ke studiu mechanických vlastností materiálů byla použita tahová zkouška, tříbodová ohybová zkouška a tlaková zkouška. Skafoldy s různými povrchy pro kostní tkáňové inženýrství byly 3D tisknuty z připravených strun s cílem určit nejoptimálnější povrch pro proliferaci buněk. Pro stanovení povrchových vlastností a jejich vlivu na adhezi buněk bylo provedeno měření optického kontaktního úhlu s využitím metody OWRK pro výpočet povrchové energie. 3D vytištěné povrchy byly také podrobeny analýze drsnosti pomocí konfokálního mikroskopu, aby byla určena jejich drsnost a její vliv na kontaktní úhel s vodou a růst buněk. Nakonec v poslední části byly ve spolupráci s Ústavem experimentální medicíny AV ČR provedeny in vitro testy na skafoldech s cílem zjistit, zda jsou připravené materiály necytotoxické, a jak povrch skafoldu ovlivňuje růst a proliferaci buněk. Bylo zjištěno, že dva ze tří materiálů nejsou cytotoxické (obě směsi poly(3-hydroxybutyrátu) s polykaprolaktonem) a že jejich mechanické vlastnosti jsou srovnatelné s lidskou trabekulární kostí. Nejoptimálnějším povrchem pro růst buněk je pravděpodobně mřížka o průměru 50 m s drsností podél perimetru 1,9 m, což odpovídá kontaktnímu úhlu s vodou 74,1°.
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Stress resistance of bacterial pure cultures and mixed cultures
Chorvátová, Michaela ; Slaninová, Eva (referee) ; Obruča, Stanislav (advisor)
The purpose of this bachelor thesis was to investigate a stress resistance of bacterial monocultures and defined mixed culture. The theoretical part contains a literary review, which deals with the general stress resistance of bacteria and the dynamics of their growth. Furthermore, polyhydroxyalkanoates are introduced, as well as their involvement into stress response of bacteria. In this review was also elaborated the flow cytometry, significant modern method, which was important part of the experiment. In the experimental part, the resistance to osmotic and temperature stress was studied. For this purpose, monocultures of the PHA accumulating strain Cupriavidus necator H16 and the mutant strain Cupriavidus necator H16/PHB-4 unable to accumulate PHA were used. The defined mixed culture was prepared by cocultivating these two strains. Overall, the accumulation and utilization of PHA, namely poly (3-hydroxybutyrate), increased the resistance of bacteria. The most notable was the increase in the case of osmotic stress, when salt concentrations did not significantly reduce the viability of Cupriavidus necator H16 against a mutant strain which viability decreased with growing intensity of stress. On the other hand, experimental temperatures did not have a significant effect on cell viability. The highest growth of bacteria was recorded, in most cases, at their temperature´s optimum of 30 °C.
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Preparation of microfiber structures based on PHB copolymer
Kecíková, Alžbeta ; Brtníková, Jana (referee) ; Přikryl, Radek (advisor)
Master’s thesis deals with the preparation of microfibrous structures based on poly(3-hydroxybutyrate) (P3HB) and its copolymer with poly(4-hydroxybutyrate) using centrifugal spinning technology. The microfibers were modified by the addition of oligomer P3HB and a plasticizer. The centrifugal spinning process was optimized for each material by solution viscosity, polymer molecular weight, speed of spineret, and presence of solvent. One of the part of optimalization was the addition of formic acid and acetic acid to the dissolution system. Microfibrous structures have been investigated in terms of morphology, mechanical properties, wetting and biocompatibility. P3HB fibers were also surface treated with lipase solutions to reduce their hydrophobicity. The prepared bulky fiber cocoons have a suitable 3D microstructure for monitoring and testing biological properties in vitro. Thus, a potential application of microfiber structures is as 3D cell culture carriers in an scaffolds in vitro system.
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Microfibers based on polyhydroxybutyrate for medical applications
Gregušková, Zuzana ; Obruča, Stanislav (referee) ; Přikryl, Radek (advisor)
Diplomová práca je zameraná na mikrovlákna na báze biopolyméru poly(3-hydroxybutyrátu) a ich využitie v medicínskych aplikáciách. Teoretická časť práce sa zaoberá štúdiom procesu tvorby vláken pomocou technológie odstredivého zvlákňovania, jeho kinetikou a faktormi ovplyvňujúcimi vznik a vlastnosti vláken. Teoretická časť sa následne orientuje na krátky prehľad biopolymérov používaných v tejto technológii, charakteristiku materiálu poly(3-hydroxybutyrátu) a taktiež prezentuje návrh potenciálnej cieľovej aplikácie daných mikrovláken. Praktická časť sa koncentruje sa prípravu mikrovláken zo spomínaného poly(3-hydroxybutyrátu). Sledované a optimalizované sú viaceré parametre vedúce k lepšej zvlákniteľnosti materiálu. Praktická časť je rozšírená o modifikáciu polymérneho roztoku prídavkom iných biopolymérov a zmäkčovadiel a prípravu mikrovláken z takto modifikovanej polymérnej zmesi. Pozornosť je venovaná taktiež optimalizácii procesných parametrov. Pripravené mikrovlákna sú následne analyzované a charakterizované viacerými metódami a vzájomne porovnávané s cieľom vyvinúť alternatívu k súčasne používaným substrátom pre rast buniek v 3D.
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Composting of biodegradable polymers
Hollá, Tereza ; Smilek, Jiří (referee) ; Obruča, Stanislav (advisor)
This master’s thesis deals with the study of composting of polyhydroxybutyrate (PHB) and polylactic acid (PLA). The experimental part focuses on the composting test based on the IS/ISO 20200 standard, in which biopolymers were degraded within 8 weeks. The advantage of the composting test was the unique use of bags for polymer granules, which simplified the handling of samples. The placement of the polymers ensured an even load of compost, which simulated the landfill environment, which also made this experiment exceptional. The use of different methods of analysis ensured the investigation of the influence of compost on the degradation of polymers, but also the influence of polymers on the compost microbiome. In the compost environment all of the studied polymers degraded. After 8 weeks the weight loss of approximately 40 % was detected in PHB. Amorphous PLA degraded completely in the 5th week of experiment, while semicrystalline PLA lost approximately 70 % of its weight in 8 weeks. Using SEM images and SEC analysis, we conclude that PHB degradation was predominantly biological. Degradation of PLA samples was found to be predominantly abiotic. Analysis of compost samples revealed that the enzymatic activity of esterases increased in composts with polymers compared to compost without polymers. The effect of polymers on the microbiome in compost was analyzed using Biolog EcoPlates™. Compost with PHB showed a high ability to adapt to various substrates and microbiome expanded during composting. In the case of a sample with semicrystalline PLA, it was found that in the last week of composting, the ability of microorganisms to adapt and use substrates decreased, which indicates a possible negative effect of this polymer on compost development.
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