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Analytical Methods of Radical Grafted Polypropylene
Zahálka, Martin ; Petruš, Josef (referee) ; Kučera, František (advisor)
The bachelor thesis deals with characterization and analyzes of radical grafted polypropylene. Analytical methods and processes used for determination of concentration of MA in grafted PP and characterization of prepared material were summarized in theoretical part. PP-g-MA samples were prepared by the homogeneous and heterogeneous technique. All the samples with unknown content of MA were analyzed by two volumetric methods. Quantitative analysis by attenuated total reflectance infrared spectroscopy (ATR–FTIR) was used. Carbonyl index was determined based on peaks of methylene (1167 cm-1) and carbonyl (1785 cm-1) groups. X-ray photoelectron spectroscopy was one of the methods used to determine concentration of MA in modified PP. Melt flow index was determined and range of -scission was discussed.
PP/PA6 polymer blend preparation
Olšan, Jakub ; Petruš, Josef (referee) ; Kučera, František (advisor)
Bachelor’s thesis studies preparation of polymer blends of polyamide 6 with polypropylene. A present knowledge about preparation of polymer blend of PA6/PP was summarized in theoretical part. Experimental part is focused on an ideal ratio of starting materials for compounding to get maximal elongation at break. At first the preparation of samples was realised in Brabender mixer at temperature of 240 °C, reaction time 6 minutes and 50 RPM. Later, samples were prepared in double-screw extruder at temperature zones between 220 and 240 °C, transition time 3,5 minutes and 90 RPM. All samples were measured on melt flow rate and tensile test. Morfology was studied by SEM. Due to SEM it was discovered that there is huge difference between compatibilized and uncompatibilized blends in their morfology. Thanks to FTIR and DSC it was proved that there is chemical bond between PA 6 and compatibilizer. Conditionation of this exact blend was done to discover the influence on mechanical properties.
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.
Reactive extrusion of polymers by peroxides
Červený, Ladislav ; Petruš, Josef (referee) ; Kučera, František (advisor)
Diploma thesis deals with processing of two types of PP, HDPE, LDPE, PET, PA, PS, PMMA and ABS by reactive extrusion in presence of peroxides. The theoretical part summarizes existing knowledge about processing of used polymers. Reactive extrusion was carried out with a single screw extruder at 260 °C, 30 rpm and 60 rpm depending on peroxide used. One type of PP was processed in presence of Luperox 101, hydrogen peroxide, dicumyl peroxide and potassium persulfate. Luperox 101 and hydrogen peroxide were chosen for reactive extrusion of other polymers. The efficiency of selected peroxides on radical modifications of individual polymers during processing was evaluated by methods of rheological (MFI), structural (FTIR) and thermal (DSC) analysis.
Softening of poly(3-hydroxybutyrate)
Brňák, Matúš ; Petruš, Josef (referee) ; Kučera, František (advisor)
The bachelor thesis deals with the inluence of PHB softening, of selected types of plasticizers. The effect of the plasticizers are compared between themselves with regard to their properties and structure. The theoretical part summarizes the knowledge about softening polymers and characterized different types of plasticizers. The experimental part deals with PHB softening in the solution and in the melt. The plasticizers ATBC, TBC, ATEC, TEC, TOTM, PVAc and butylglycolate dilution containing 30 wt % were added to the PHB previously dissolved in chloroform. In the case of softening in the melt, a polymer paste was prepared, containing 70 wt % of plasticizers and 30 wt % of PVAc. The mixture was plasticized in a mixer, wherein time and temperature of the gelatinization were determined experimentally. Thermal degradation of preprared samples were specified by TGA. Values of Tg, Tm and Xc, was determined by DSC analysis. The samples plasticized in the melt were determined by the hardness of the material according to the Shore A scale and the Vickers scale.
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.
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.
Stabilizing epoxide systems in surface protective varnishes
Švardala, Daniel ; Tocháček, Jiří (referee) ; Petruš, Josef (advisor)
The diploma thesis describes the influence of humid conditions on the curing of epoxy resins by multifunctional amines. The aim of the experimental part was the identification of degradation products and their quantification, as well as the determination of the influence of humid conditions on the degree of hardening, modulus of elasticity, and flexural strength. Another goal was to optimize the formulation of the reactive mixture for the preparation of epoxy resin with lower susceptibility to carbamate bloom. The degradation products were evaluated by determining the mechanical properties by bending test according to the standard ČSN EN 179-1. The degree of hardening was monitored through temperature modulated differential scanning calorimetry (TMDSC). Degradation products were identified by Fourier transform infrared spectroscopy (FTIR) and quantified by UV-VIS spectroscopy. The morphology of the surface layer was monitored by confocal laser scanning microscopy (CLSM). The dependence of the relative humidity of the environment on the curing process of the epoxy resin and its resulting mechanical properties was determined. Based on the analyzes, a modification of the formulation for the suppression of spurious carbamate during the curing of the epoxy matrix was designed and experimentally verified.
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.
Grafting VTMOS onto PHB
Novotný, Igor ; Petruš, Josef (referee) ; Kučera, František (advisor)
Diploma thesis deals with the grafting of vinyltrimethoxysilane (VTMOS) onto poly(3–hydroxybutyrate)PHB. Subsequent characterization of the amount of grafted VTMOS and changes in the thermal properties associated with the rate of crystallization. The theoretical part deals with mechanism and the influences of grafting. In the experimental part VTMOS was grafted onto PHB without subjecting VTMOS to hydrolysis and subsequent crosslinking. By differential scanning calorimetry (DSC) and Avrami equation, the effect of grafted silane group on pure was studied. The MVR was used to compare the rheological properties of initial PHB, grafted PHB and crosslinked PHB by siloxane linkages.

National Repository of Grey Literature : 58 records found   previous11 - 20nextend  jump to record:
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