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Biodegradation of 3D printed composites based on poly(3-hydroxybutyrate)
Gazdová, Nikol ; Menčík, Přemysl (referee) ; Melčová, Veronika (advisor)
This bachelor thesis deals with the biodegradation of 3D printed bodies composed of poly(3- hyroxybutyrate), polylactic acid, bioceramics and plasticizer. These components were selected for their biocompatibility and properties that could be used in tissue engineering as a temporary, absorbable bone tissue replacement. The main objective was to investigate the effect of the individual constituent bodies on the biodegradation itself. Biodegradation was carried out at 37 °C in a solution simulating the ionic concentration of blood plasma. Samples were sequentially withdrawn at monthly intervals for five months. To evaluate the results, 2 methods were used, weight change and compression test, where the strength of each body was evaluated. From the evaluation of the data it was not possible to reach a uniform result on which substance influences biodegradation the most, because it always depended on the ratio of the other substances. To investigate the effect of poly(3-hydroxybutyrate) and polylactic acid on the rate of biodegradation, mixtures of RP9, RP10 and RP15 were compared. It showed that a higher polylactic acid and lower poly(3-hydroxybutyrate) content had a significant positive effect on the biodegradation rate, as the difference between the weight loss for the RP9 blend with the highest poly(3-hydroxybutyrate) content and the RP10 blend with the highest polylactic acid content was 8.37% for solid bodies and 4.13% for porous bodies. For strength, the difference was 73.32% and 73.65% for the solid and porous bodies, respectively. Observing the effect of bioceramic content on the RP11, RP12 and RP15 mixtures, we concluded that this effect was almost negligible on the biodegradation rate The difference in weight loss between the RP11 mixture with the lowest bioceramic content and the RP12 mixture with the highest bioceramic content was only 1, 68 % for solid bodies and 0.99 % for porous bodies, while mixture RP15 showed the highest biodegradation rate despite having a medium value of bioceramics in the mixture. For the mechanical properties, this then amounts to a difference of 10.4% for the solids and 7.57% for the porous bodies. When comparing the effect of plasticizer for mixes RP13, RP14 and RP15, the effect was more on the strength drop, where the difference in strength drop for mix RP13 with the lowest plasticizer content and RP14 with the highest plasticizer content was different by 20.3% and 18.16% for the solid and porous body, respectively. The decrease in weight was then different by 4.1 % and 0.83 % for the solid and porous body, respectively. Finally, bioceramics from different companies emerged as an important element for the biodegradation rate. Hydroxyapatite from Applichem was the best biodegraded and hydroxyapatite from CN Lab was the worst. The difference for weight loss was 17.35% for the solid and 5.93% for the porous body. The strength loss was then different by 55.6% for the solid body and 33.38% for the porous body.
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Biodegradable plastics
Schifferová, Zuzana ; Jan, Vít (referee) ; Molliková, Eva (advisor)
The aim of this bachelor theses is to discuss the process of biodegradation occurring with biodegradable polymers including factors affecting this process. The theses also introduces some types of biodegradable plastics including their properties. At last it discusses waste management of these plastics and their ecological impact.
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Influence of selected agents on crystallization power of polylactide
Kurakin, Yuriy ; Přikryl, Radek (referee) ; Bálková, Radka (advisor)
The influence of seven additives on the crystallization ability of polylactide (PLA), melt flow index (MVR) and mechanical tensile properties was studied. Pressed plates with a thickness of 0.8 mm were tested. Selected additives added in amounts of 0.5 and 1.0% were as follows: talc, sodium benzoate, mixtures of organic salts with amorphous SiO2 and zinc stearate, metal salt, phosphate salt, and potassium salt of 5-dimethylsulfoisophthalate (LAK-301 - nucleating agent developed for PLA). Non-isothermal crystallization measurements were performed at different cooling rates (0.3; 0.5; 0.7; 1.0 and 1.5 ° C). All nucleation agents increased the MVR of PLA except talc; the largest increase (9-fold and 24-fold) was the addition of metal salt. The additives did not fundamentally change the mechanical properties. All samples were rather brittle (the most brittle with LAK-301), the modulus of elasticity was around 1.2 GPa for all samples, the strength of PLA was increased the most by the addition of 1% talc (by 12%) and the elongation at break was increased by organic salt with SiO2. All samples with nucleating agents content of 1% were amorphous (crystalline content did not exceed 2%). Thus, the addition of reagents did not support the crystallization process during rapid cooling, even in the case of LAK-301. However, LAK-301 was acting as an excellent nucleating agent at slow cooling rates (1.5 °C / min and below). The nucleation activity of the additives decreased in the following order: LAK-301, organic salt with zinc stearate, talc, organic salt modified with amorphous SiO2 and phosphate salt. Samples with sodium benzoate and metal salt were crystallizing on cooling in several steps and it was not possible to use the method of Dobrev and Gutzow to evaluate the nucleation activity.
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Kinetics of non-isothermal crystallization of polylactide with selected agents
Červený, Ľuboš ; Tocháček, Jiří (referee) ; Bálková, Radka (advisor)
The aim of submitted diploma thesis is the study of non-isothermal crystallization kinetics of polylactide (PLA) with selected agents (1 %) and observation of the emerging crystalline structure under polarizing optical microscope. The agents were talc, a mixture of organic salts with the addition of amorphous SiO2 (HPN 68L) and zinc stearate (HPN 20E) and LAK-301 (potassium salt of 5-dimethylsulfoisophtalate), which is a nucleating agent developer for PLA. The PLA matrix served as a reference. Non-isothermal crystallization took place on a differential scanning calorimeter at cooling rates () 0,3; 0,5; 0,7; 1; 1,5; 2 °C/min After non-isothermal crystallization, the crystalline fraction (Xc) od PLA was evaluated from X-ray diffraction analysis, and the supramolecular structure was observed after chemical degradative etching using confocal laser scanning microscope. The crystallization kinetics were evaluated by the methods of Jeziorny and Mo and the activation energy of the crystallization was determined according to the Friedmann method. All prepared materials were amorphous (Xc 40 % for up to 1,5 °C/min). However, for LAK-301, Xc decreased to 30 % already at the = 2 °C/min and it can be assumed that with increasing its nucleation activity will decrease. A spherulitic structure was observed in all samples, but the number and size of spherulites decreased with increasing and the appearance varied according to the type of agent. Both kinetic models proved to be unsuitable for materials with low Xc and the highest because the rate of crystallization did not change. With the Jeziorny method, it was possible to evaluate the kinetics only for the relative crystallinity Xt = 29–50 % and with the Mo method it was not possible to evaluate the data for the highest for PLA matrix and sample with HPN 68L. The samples with LAK-301 and HPN 68L showed the lowest activation energy.
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Modification of PLA using reactive extrusion
Matláková, Jana ; Petrůj, Jaroslav (referee) ; Kučera, František (advisor)
Diplomová práce se zabývá roubováním maleinanhydridu a anhydridu kyseliny itakonové na kyselinu poly(mléčnou) (PLA). U modifikované kyseliny poly(mléčné) byla sledována závislost konverze monomerů na různých molárních poměrech monomer/iniciátor při teplotách 180°C a 200°C. Množství naroubovaného monomeru bylo stanovováno acidobazickou titrací a pomocí FT-IR spektroskopií. Vliv stupně naroubování na krystalinitu modifikované PLA byl zjišťován pomocí diferenční kompenzační kalorimetrie, DSC. Degradace PLA byla orientačně pozorována pomocí indexu toku taveniny, MFI.
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Blends of PLA with thermoplastics
Petruš, Josef ; Petrůj, Jaroslav (referee) ; Kučera, František (advisor)
Diploma thesis deals with preparation of polymer blend of polymer A and polymer B. Knowledge of polymer blends forming, thermodynamics and function of compatibilizer is contained in the theoretical part. Polymer blend A/B of weight ratios 75/25, 50/50 and 25/75 wt% were prepared by physical compatibilization. Concentration of compatibilizer was 5 wt%, in the case of A/B 50/50 wt% concentration of compatibilizer was 10 and 30 wt%, respectively. Blending was achieved with twin-screw extruder at 230 °C and 100 rpm. Second method used for A/B blending was based on reactive compatibilization which was achieved with Brabender kneader at 230 °C, 50 rpm and reaction time 10 minutes. Concentration ratios of A/B were 75/25, 50/50 and 25/75 wt%. Itaconic acid anhydride and maleic anhydride 0.5 and 5 wt% were used as monomer. 2,5-dimethyl-2,5-bis(tert-buthylperoxy)hexan was (Luperox 101) used as an initiator. Difference between compatibilized and noncompatibilized blends was characterized by scanning electron microscopy, tensile test, differential scanning calorimetry, melt flow index measuring, acid-base titration and FT-IR spectroscopy.
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Effect of chemical structure of plasticizer on material properties based on polyhydroxybutyrate
Stehnová, Ivana ; Alexy, Pavol (referee) ; Přikryl, Radek (advisor)
This master’s thesis deals with plasticization of poly(3-hydroxybutyrate), polylactid acid and their blend. It explores effect of chemical structure of plasticizer on mechanical properties of this polymer blend and on its diffusion from the polymer blend. Syntheses of plasticizers based on oligomeric polyadipates, citrates, lactate and esters of 2 ethylhexanoic acid with poly(ethyleneglycol) were carried out. Molecular weight distribution of synthesized plasticizers was determined using gel permeation chromatography. Poly(3-hydroxybutyrate), polylactid acid and their blend were plasticized with synthesized and commercial plasticizers. From commercial, chosed plasticizers were based on citrates and ester of 2-ethylhexanoic acid with poly(ethyleneglycol). Thermal stability of selected commercial plasticizers in polylactid acid was studied using thermogravimetry. Diffusion of plasticizers from poly(3-hydroxybutyrate), polylactid acid and their blend during exposure to 110 °C was also investigated. Mechanical properties of prepared blends were tested by tensile test. Almost all used plasticizers showed positive softening effect in blend. The highest elongation at break was detected for the blend with commercial acetyltributylcitrate, where elongation at break reached 328 % relative to 21 % for neat non-plasticized blend.
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In vitro biodegradation of biopolyesters exposed to synthetic gastric juice
Sobková, Markéta ; Skoumalová, Petra (referee) ; Kovalčík, Adriána (advisor)
This bachelor’s thesis is focused on the study of in vitro biodegradation of biopolyesters exposed synthetic gastric juice and phosphate buffer saline with lipase for 81 days. The theoretical part summarises the necessary information about characteristics of biodegradable biopolyesters, deals with their possible applications in medicine. The experimental part deals with the biodegradation of prepared biopolyesters films. in this work, poly(lactic acid), amorphous poly(hydroxy alkanoates), poly(3-hydroxybutyrate), poly(butylene adipate terephthalate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), filament poly(lactic acid) and filament poly(lactic acid)/poly(hydroxybutyrate) were used for the experiment. The films were prepared by dissolving of the biopolyesters in hot chloroform. The dissolving agent was evaporated, and prepared films were dried. Prepared films had different properties depending on the used biopolyesters. Their appearance was formed transparent to milky cloudy. Also, trey differed in their plasticity. During biodegradation, the morphology changed, and the samples gained higher fragility. The effect of biodegradation was monitored by changes in 1) molecular weights (SEC-MALLS), 2) chemical structure (FTIR) and 3) weight loss changes (gravimetrically). The analysed biopolyesters were demonstrably susceptible to biodegradation in simulated body conditions. The degree of biodegradation depends on the type of biopolyester. The most significant weight loss was recorded for the sample of amorphous polyhydroxyalkanoate (PHA). The PHA´original weight was reduced about 84.28 ± 0.03 % after the 81 days of biodegradation in the phosphate-buffered saline with lipase.
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Study on biotechnological potential of thermophilic gram-positive bacterium Brevibacillus sp. Bz
Filimonova, Anastasiia ; Obruča, Stanislav (referee) ; Pernicová, Iva (advisor)
Předmětem předložené diplomové práce je studium biotechnologického potenciálu termofilní grampozitivní bakterie Brevibacillus borstelensis BZ. Teoretická část obsahuje obecnou charakterizaci termofilních organismů a jejich termozymů. Popisuje také adaptivní molekulární mechanismy, které zajišťují termostabilitu těchto proteinů. Závěr teoretické části je věnován biodegradaci odpadních substrátů a polymerů na bázi přírodních a fosilních zdrojů. První část experimentální práce se zabývá produkcí hydrolytických enzymů na různých původních zdrojích a odpadních substrátech. Díky intenzivní enzymatické produkci na původních zdrojích je Brevibacillus borstelensis BZ považován za velmi slibného producenta termostabilních enzymů, konkrétně xylanáz a celuláz. Testovaný bakteriální kmen BZ byl schopen produkce termostabilních enzymů i na odpadních substrátech. Na vybraných substrátech kmen BZ přednostně produkoval xylanázy. Díky tomu byla xylanázám věnována zvláštní pozornost, kdy bylo testováno teplotní a pH optimum. Závěrem experimentální práce byla testována schopnost bakterie Brevibacillus borstelensis BZ degradovat vybrané polymery na bázi přírodních a fosilních zdrojů. Kmen BZ poskytl nový pohled na biologický rozklad polyethylentereftalátu (PET), amorfní frakce kyseliny polymléčné (PLA), semikrystalické PLA a polyhydroxyalkanoátů (PHA). Pozorováním povrchu PET fólie skenovacím elektronovým mikroskopem (SEM) se potvrdilo zdrsnění materiálu, přítomnost rýh a naprosté pronikání bakterie skrz fólii. Pokud jde o polymery na bázi přírodních zdrojů, PHA granule byly zcela degradovány. Studiem morfologie povrchu obou zmíněných PLA bylo prokázáno jasné zhoršení jejich struktury přítomností jam a trhlin na povrchu polymerů.
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Biodegradation of 3D printed composites based on poly(3-hydroxybutyrate)
Gazdová, Nikol ; Menčík, Přemysl (referee) ; Melčová, Veronika (advisor)
This bachelor thesis deals with the biodegradation of 3D printed bodies composed of poly(3- hyroxybutyrate), polylactic acid, bioceramics and plasticizer. These components were selected for their biocompatibility and properties that could be used in tissue engineering as a temporary, absorbable bone tissue replacement. The main objective was to investigate the effect of the individual constituent bodies on the biodegradation itself. Biodegradation was carried out at 37 °C in a solution simulating the ionic concentration of blood plasma. Samples were sequentially withdrawn at monthly intervals for five months. To evaluate the results, 2 methods were used, weight change and compression test, where the strength of each body was evaluated. From the evaluation of the data it was not possible to reach a uniform result on which substance influences biodegradation the most, because it always depended on the ratio of the other substances. To investigate the effect of poly(3-hydroxybutyrate) and polylactic acid on the rate of biodegradation, mixtures of RP9, RP10 and RP15 were compared. It showed that a higher polylactic acid and lower poly(3-hydroxybutyrate) content had a significant positive effect on the biodegradation rate, as the difference between the weight loss for the RP9 blend with the highest poly(3-hydroxybutyrate) content and the RP10 blend with the highest polylactic acid content was 8.37% for solid bodies and 4.13% for porous bodies. For strength, the difference was 73.32% and 73.65% for the solid and porous bodies, respectively. Observing the effect of bioceramic content on the RP11, RP12 and RP15 mixtures, we concluded that this effect was almost negligible on the biodegradation rate The difference in weight loss between the RP11 mixture with the lowest bioceramic content and the RP12 mixture with the highest bioceramic content was only 1, 68 % for solid bodies and 0.99 % for porous bodies, while mixture RP15 showed the highest biodegradation rate despite having a medium value of bioceramics in the mixture. For the mechanical properties, this then amounts to a difference of 10.4% for the solids and 7.57% for the porous bodies. When comparing the effect of plasticizer for mixes RP13, RP14 and RP15, the effect was more on the strength drop, where the difference in strength drop for mix RP13 with the lowest plasticizer content and RP14 with the highest plasticizer content was different by 20.3% and 18.16% for the solid and porous body, respectively. The decrease in weight was then different by 4.1 % and 0.83 % for the solid and porous body, respectively. Finally, bioceramics from different companies emerged as an important element for the biodegradation rate. Hydroxyapatite from Applichem was the best biodegraded and hydroxyapatite from CN Lab was the worst. The difference for weight loss was 17.35% for the solid and 5.93% for the porous body. The strength loss was then different by 55.6% for the solid body and 33.38% for the porous body.
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