National Repository of Grey Literature 58 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Influence of carbon based filler aplication to termoplastics and its properties observation
Lahoda, Ondřej ; Petruš, Josef (referee) ; Kučera, František (advisor)
This bachelor thesis focuses on studying the effect of expanded graphite (EG) on the properties of two thermoplastics with different supramolecular structures, amorphous PETG and semicrystalline PA6. The aim was to analyze how the electrical, mechanical, and flow properties of the prepared composites change depending on the volume concentration of EG. Samples with EG volume concentrations ranging from 3% to 27% were prepared using a Brabender measuring mixer. Experiments were performed using standardized methods, including MFI (melt flow index) measurements according to ISO 1133, tensile property testing, and electrical resistance measurements. The morphology of the prepared samples was analyzed using a scanning electron microscope. The crystallinity of the sample with PA6 matrix was analyzed using a differential scanning calorimetry. The effect of EG concentration on composite properties such as electrical conductivity, tensile modulus and flow properties was observed.
The influence of filler on the properties of softened PVC
Loprais, Štěpán ; Kučera, František (referee) ; Petruš, Josef (advisor)
Bachelor thesis deals with application of fillers into softened PVC. Theoretical part describes additivation of PVC with focus on functional properties and thermal and UV stability. Practical part deals with application of expanded graphite into softened PVC and characterization of the newly created materials. For the purpose of describing influence of expanded graphite on softened PVC, a series of samples were prepared and tested with differing concentration of expanded graphite. These samples have been subjected to accelerated UV aging with UV-A exposition times up to 960 hours. Chemical changes within the material were examined with FTIR. The degree of photo-oxidation has been measured by tensile strength and maximum deformation in tensile mechanical tests. Chosen parameters taken from thermic stability and decomposition profile were closely examined in TGA analysis. Changes of phase transition as indicators of degradation and plasticizer loss in PVC were examined by DSC. Morphology of samples were examined by SEM after UV exposition. Based on the results of characterization methods the application of expanded graphite was evaluated.
Polymeric blends of thermoplastic starch with other biodegradable polymers
Nováková, Pavlína ; Petruš, Josef (referee) ; Kučera, František (advisor)
The master's thesis deals with the preparation and properties of biodegradable polymer blends of thermoplastic starch (TPS) with polyhydroxybutyrate (PHB) with emphasis on the compatibilization of the immiscible polymer blend. The theoretical part focuses on the characterization of thermoplastic starch, thermodynamics of polymer blends, possible ways of compatibilization of polymer blends and a summary of the current knowledge on polymer blends of thermoplastic starch with biodegradable polymers. The experimental part deals with the modification of starch and PHB with maleic anhydride in order to compatibilize the polymer blend. The binding of the monomer to the polymers was confirmed by infrared spectroscopy and acid-base titration. Subsequently, using the prepared modified polymers, TPS/PHB blends were prepared and the effect of compatibilization and blend composition on the properties was evaluated. Differential scanning calorimetry (DSC) was used to observe the melting and crystallization process, the changes in molecular weight of the polymers were assessed by determining the melt flow index. Tensile strength, elongation at break and the effect of ageing on the mentioned mechanical properties were determined by tensile testing, morphology was observed by electron microscopy (SEM).
Optimization and characterization of dimethacrylate-based resin
Baradzina, Lizaveta ; Petruš, Josef (referee) ; Poláček, Petr (advisor)
This diploma thesis was focused on the optimization and characterization of resins based on dimethacrylate monomers. The polymerization process was also monitored depending on the type and molar ratio of monomers used, on the content of barium glass filler and the presence of glass fibers. Changes in the viscoelastic properties of materials during polymerization were also investigated. The following methods were used to characterize the prepared dimethacrylate resins and composite materials based on them: viscosimetry, differential scanning photocalorimetry (DPC), photoreology, dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA). The dynamic viscosity of the prepared dimethacrylate matrices was determined by viscometry. Based on the results of DPC analysis of the tested resins, the dependences of heat flow on time, conversion on time and polymerization rate on conversion were created. With photoreology, the course of curing, the onset of the gelation point and changes in the viscoelastic properties of the systems were monitored. The viscoelastic properties of the cured composite materials were then determined by DMA in the three-point arrangement. TGA was performed to accurately determine the composition of the tested samples
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.
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.
Controlled life-time polypropylene
Demková, Eva ; Petruš, Josef (referee) ; Tocháček, Jiří (advisor)
The master´s thesis is focused on the characterization of degradation process of polypropylene and polypropylene with statistic copolymer into which manganese (II) stearate and cobalt (II) stearates were added at 0.05, 0.10 and 0.20 wt.% loadings. The aim of the thesis was to prepare the controlled life-time polypropylene. The degradation was studied at varying temperatures and prodegradant loadings. The prodegradants were synthetized and characterized using the FTIR and DSC techniques. Thermooxidation of the tested samples induced the changes in crystallinity, melting points and melt-flow indexes. Tensile strength and other mechanical properties were determined by means of the tensile test. The carbonyl index was determined using FTIR, the thermooxidation stability test was used to determine the activation energies of reactions. The changes in morphology of degraded samples were observed by SEM analysis.
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.
Grafting of PP using itaconic anhydride and drying agent
Petruš, Josef ; Hermanová, Soňa (referee) ; Kučera, František (advisor)
The bachelor´s thesis deal with a preparation of polypropylene (PP) grafted with itaconic acid (IA) and itaconic anhydride (IAH) arising by thermic dehydration in situ from IA in presence of drying agents. Theoretical part contains actual knowledges especially about radical grafting of polypropylene with different monomers. In experimental part samples of polypropylene grafted with 0.5 wt % IA were prepared with free different drying agents: calcium oxide, aluminium oxide and calcium sulfate hemihydrate. To comparison PP grafted with 0.5 wt % IAH was prepared. Thermic behaviour of IA with drying agent and IAH samples was determined by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) measurement. Process of grafting was realized with mixer Brabender at temperature 230 °C, speed was 30 RPM and reaction time 6 minutes. 2,5-dimethyl-2,5bis(tert-buthylperoxy)hexane (Luperox 101) was used as iniciator. Percentage of grafted carboxylic groups was provided by acid-base titration. FTIR spectroscopy was used for quantitative and qualitative analysis of characteristic groups.
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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