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Technology of injection molding of thermoplastic test specimens
Khamzin, Yersin ; Petruš, Josef (referee) ; Kučera, František (advisor)
The diploma thesis focuses on the optimization of technological parameters of plastic injection molding and the study of the influence of technological parameters on the quality of molded test specimens’ type 1A. The quality of molded parts for 3 types of polypropylene (PP) with different melt flow rate (Mosten GB 002, Mosten GB 218, Mosten MA 230) and 1 type of polystyrene (PS) (Krasten PS GP 154) was evaluated in terms of dimensional stability and weight. The contribution of software for modeling the plastic injection molding process was evaluated in this work. SOLIDWORKS Plastics software was used to optimize technological parameters. The construction of the bodies, mold and cooling system was constructed, and test bodies were produced on the basis of parameters obtained from the simulation of the injection molding process. Their quality parameters were compared with a 3D model and for each of the studied materials the optimal technological parameters were selected in terms of quality and the degree of influence of individual injection parameters on the quality of moldings was evaluated. The accordance of the results of the theoretical simulation with the real experiment was proved and a computational module independent of the optimized quality parameters, generally suitable for optimizing the quality parameters of the injected parts, was developed.
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Preparation and characterization of graphene/polymer composites
Zálešáková, Romana ; Petruš, Josef (referee) ; Poláček, Petr (advisor)
The aim of the master’s thesis is study of polymer composite system with the addition of graphite, production of test specimen and determination of their mechanical and thermal properties. The theoretical part deals with graphene, its structure, preparation and properties. Subsequently, it deals with functionalization and derivates and nanocomposites polymers with the addition of graphene are generally analyzed. The experimental deals with the preparation of selected specimens. Tensile and laternal tests and DMA were used for study.
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Application and properties of silicone textile coatings
Bernátová, Silvia ; Petruš, Josef (referee) ; Kučera, František (advisor)
The diploma thesis in the first part deals with a theoretical description of coating technologies, textile materials used in coatings, types of coated polymers and properties of coatings - especially adhesion. The experimental part of the work is devoted to the preparation of textile coatings from polyester fabric and coating based on addition silicone. Using the developed method of sample preparation for T-peel testing of the adhesive strength, the improvement of the adhesion of the coating by chemical adhesion with the support of adhesive agents was studied. The second method studied the change in compactness and adhesion of the coating to the fabric after shaking as a function of breathability. The influence of side reactions of reagents on silicone cohesion was studied by preparing dogbones for testing tensile-deformation properties. The research also included the characterization of silicone samples using ATR-FTIR, monitoring the weight gain and thickness of the fabric after coating, the feel and color stability of the applied fabric and observing the coating under an optical microscope.
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Functionalization of Polypropylene by Maleimides
Korčušková, Martina ; Petruš, Josef (referee) ; Kučera, František (advisor)
Diploma thesis deals with preparation of polypropylene functionalized by maleimides, based on the reaction between maleic anhydride and amine. The overview of functionalization of polypropylene by maleic anhydride by reactive extrusion and routes for the synthesis and utilization of maleimides are contained in the theoretical part. Samples of maleimide-functionalized polypropylene were prepared by reactive extrusion using low molecular weight amines (aniline and 4-aminophenol) and hight molecular weight polyether monoamines. Functionalized polypropylene samples were prepared by several methods differing in the composition of the reaction mixture and performing a grafting reaction. Appropriate maleamic acids and maleimides were synthesized from low molecular weight amines and further used to functionalize the polypropylene. To characterize the samples, the degree of monomer conversion and melt flow index were determined and further analyses were performed by Fourier transform infrared spectroscopy, differential scanning calorimetry and thermogravimetric analysis. The synthesis of low molecular weight products was further monitored by thin layer chromatography and thermogravimetric analysis with evolved gas analysis.
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Post-polymerization modification of polyolefins for the preparation of hydroxylated macroinitiators
Boldovjaková, Tatiana ; Kučera, František (referee) ; Petruš, Josef (advisor)
The diploma thesis deals with post-polymerization hydroxylation of polypropylene in solid state. Regarding the literature review, polypropylene was hydroxylated by radical grafting in aqueous solution of potassium persulfate at 100 °C, under nitrogen atmosphere for 60 minutes. Hydroxylation of polypropylene was performed at different concentrations of potassium persulfate (1; 5; 10 mol. %) and two different water/potassium persulfate molar ratios. The effects of reaction system composition and reaction conditions on reaction efficiency, extent of side reactions, thermal and rheological properties of hydroxylated polypropylene were evaluated. The presence and concentration of hydroxyl groups on polypropylene surface was determined by structural analysis (FTIR, XPS), while the highest efficiency was achieved in the presence of nonionic wetting agents, using 10 mol. % potassium persulfate and at lower water/potassium persulfate molar ratio. Based on changes in polypropylene structure, the modification took place mainly in the amorphous phase of the polymer. In addition to hydroxylation, concurrent side reactions have been reported, in particular the oxidation of wetting agents and polypropylene, which has resulted in chain cleavage, reducing the average molecular weight of the polypropylene.
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Photopolymerization study of composites
Baradzina, Lizaveta ; Petruš, Josef (referee) ; Poláček, Petr (advisor)
This bachelor thesis investigated the influence of ceramic nanofibers and particle filler on the curing kinetics of composite materials with dimethacrylate matrix. Changes in viscoelastic properties of materials during polymerization were also monitored. Within this work, four types of materials were prepared: particle composite, fiber composite, hybrid composite and pure matrix. Composite systems of different compositions were characterized by photorheology, differential photocalorimetry (DPC), and dynamic-mechanical analysis (DMA). The effect of light intensity and irradiation time on changes in the rheological properties of materials that occur during photopolymerization were investigated using photorheology. Based on the results of DPC analysis of the tested samples the dependencies of conversion on time and polymerization rate on conversion were created. The viscoelastic properties of the cured composites were determined by DMA analysis in a three-point arrangement.
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Compatibilization of polymeric blends of poly(lactic acid) PLA
Boldovjaková, Tatiana ; Kučera, František (referee) ; Petruš, Josef (advisor)
The bachelor thesis deals with reactive compatibilization of polymer blend of poly(lactic acid) and polyamide 6 of weight ratios 20/80. The method of reactive compatibilization of poly(lactic acid) and polyamide 6 in laboratory kneader at 230 °C and 60 rpm was chosen based on knowledge introduced in the literature review. These blends were reactively compatibilized by poly(lactic acid) grafted with itaconic anhydride, multifunctional epoxide Joncryl, poly(itaconic anhydride) and organic peroxide 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane (Luperox 101) at different concentrations for 4 minutes. The effects of reactive compatibilizers and its concentration on morphological, thermal and rheological properties of blends were investigated. Reactive compatibilizer Joncryl improved interfacial adhesion, reduced particle size of dispersed phase, improved thermal stability of blends when compared to uncompatibilized blend. The results show that Joncryl is an effective reactive compatibilizer for blend of poly(lactic acid) and polyamide 6. Poly(lactic acid) grafted with itaconic anhydride did not show desired effect due to the low concentration of anhydride groups. After the addition of poly(itaconic anhydride) and Luperox 101 into the poly(lactic acid)/polyamide 6 blends, side reactions occurred, which was proved by rheological and morphological properties of these blends.
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Hydrolytical stability of poly(3-hydroxybutyrate)
Korčušková, Martina ; Petruš, Josef (referee) ; Kučera, František (advisor)
The bachelor thesis deals with the study of hydrolytical stability of poly(3-hydroxybutyrate) in the hydrolysis with excess of water and in the hydrolytic degradation in melt. Theoretical part summarises knowledge about the process, mechanism and kinetics of hydrolysis and contains an overview of further decomposition reactions of poly(3-hydroxybutyrate). Experimental part is focused on degradation of poly(3-hydroxybutyrate) in the presence of water and on comparing the rate of hydrolytical degradation with acidic and alkaline catalysis. In order to comparing the range of hydrolysis, hydrolytic degradation of poly(3-hydroxybutyrate) was investigated in extruder at the temperature of 170 °C. Samples were analyzed to determine the melt volume index, melt temperature, degree of crystallinity, distribution of molecular mass and the structure of poly(3 hydroxybutyrate) using infrared spectroscopy.
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Heterogeneous Radical Modification of Polypropylene
Brňák, Matúš ; Petruš, Josef (referee) ; Kučera, František (advisor)
The diploma thesis deals with the heterogeneous technique of preparation of grafted polypropylene g maleic anhydride (PP-g-MAH). The knowledge of the course of the reaction and its impact on the PP grafting process are summarized in the theoretical part. The preparation of the grafted PP was carried out in a fluidized polymerization reactor at 115 °C, speed of mixing 210 rpm, reaction time 60 min and pressure 6 bar. The amount of grafted MAH was monitored by using a MAH concentration 3 and 5 wt% and an initiator concentration 0.25; 0.5; 1; and 1.5 wt%. Modification efficiency was compared by using 3 types of PP with different particle morphology and specific surface area. By creating the theoretical model, the maximum surface concentration of MAH was calculated and compared with experimental data. Characterization of PP materials was performed by Electron Scanning Microscopy (SEM), Differential Scanning Calorimetry (DSC) and particle surface analysis by BET. Quantitative analysis of grafted MAH was determined by FTIR spectroscopy and acid-base titration.
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