National Repository of Grey Literature 58 records found  beginprevious49 - 58  jump to record: Search took 0.00 seconds. 
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.
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.
Functionalization of polyolefins by grafting
Paulenka, Igor ; Petruš, Josef (referee) ; Petrůj, Jaroslav (advisor)
The theoretical part of the diploma thesis is focused on the funcionalization of polyolefins in order to accelerate their degradation and to increase their carbon content from renewable resources with focus on hydroxyacids. The experimental part is focused on preparing samples and studying the properties of the polypropylene and polyethylene blends with the polylactide with different contents of the initiator and the maleic anhydride. Samples were evaluated by determining the degree of conversion maleic anhydride, differential scanning calorimetry, infrared spectroscopy, melt flow index and mechanical properties.
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.
Inflence of technological conditions and polyhydroxybutyrate materials composition on crystallinity
Olšan, Jakub ; Petruš, Josef (referee) ; Kučera, František (advisor)
Diploma thesis is summarizing sources and technology of PHB and its physical and chemical properties compared to other polymers. Thesis mentions usage and function of certain additives in PHB matrix and their impact on the final product. Practical part of the thesis is concerned with technological parameters and degradation of the PHB during extrusion. The thesis also observes behaviour of nucleating agents on crystallinity and crystallization properties of prepared compounds. Degradation was analyzed by MFI and colour difference against standard material, FTIR was not successfully used for the purpose of degradation. Crystallinity and crystallization behaviour was analysed by DSC and optical microscopy with heated operating table. Graphs were created from results of analysis and suitable usage of each nucleating agent was considered. Boron nitride was selected as the most suitable nucleating agent due to creating higher amount of smaller spherulites.
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 Poly(Lactic Acid)
Petruš, Josef ; Pospíšil, Ladislav (referee) ; Alexy,, Pavol (referee) ; Petrůj, Jaroslav (advisor)
Teoretická část předložené dizertační práce popisuje princip radikálového roubování a faktory ovlivňující reakční průběh. Radikálové roubování poly(mléčné kyseliny) (PLA) reaktivní modifikací je vhodnou technikou přípravy biodegradabilních polymerních materiálů s rozličnými vlastnostmi. Současný stav problematiky modifikace poly(mléčné kyseliny) radikálovým roubováním v tavenině je obsahem literární rešerše včetně možných aplikací. Experimentální část se zabývá modifikací PLA anhydridem kyseliny itakonové (IAH) radikálovým roubováním v tavenině. Reakce byla iniciována 2,5-bis(tert-butylperoxy)-2,5-dimethylhexanem (L101). V první části je průběh radikálového roubování pozorován “in situ” pomocí diferenciální kompenzační kalorimetrie (DSC) a termogravimetrické analýzy (TGA). Exotermní pík na DSC záznamu odpovídá průběhu radikálové reakce, na jehož základě lze definovat aktivační energii reakce. Průběh TGA křivky “in situ” radikálové reakce umožňil detekovat vedlejší produkty vznikající v průběhu radikálové modifikace. Ve druhé části byla PLA funkcionalizována reakcí v diskontinuálním laboratorním mixéru za reakčních podmínek navržených dle poločasu rozpadu zvoleného iniciátoru a zpracovatelských podmínek PLA. Reakční teplota 190 °C byla stanovena výpočtem z Arrheniovy rovnice pro reakční čas 6 min. Uvedené reakční parametry byly zvoleny s ohledem na kinetiku rozkladu L101 a potlačení degradace PLA. Infračervená spektroskopie (FTIR) potvrdila navázání IAH na PLA řetězec na základě výskytu –CH2 vibrací s absorpčními pásy při vlnočtu 2860 a 2920 cm-1. Vzrůstající intensita absorpčního pásu 1750 cm-1 potvrdila přítomnost minoritních C=O vibrací anhydridového kruhu překrytých dominantními C=O vibracemi PLA řetězce. Nukleární magnetická rezonance (1H-NMR) nepotvrdila roubování oligomerního IAH na PLA. Koncentrace reaktantů ve zvoleném rozsahu (0.5–10 hm % IAH, 0.1–2 hm % L101) byla použita pro posouzení jejího vlivu na obsah naroubovaného IAH a míru vedlejších reakcí, např. -štěpení, větvení a síťování. Při vysoké koncentraci IAH a L101 byla potvrzena homopolymerace IAH i přes její zanedbávání v tématicky podobných studiích. Tvrzení o IAH homopolymeraci bylo podpořena výsledky kolorimetrické analýzy, charakterizací vzorků připravených polymerací IAH za podmínek radikálového roubování a termickou stabilitou frakcí extrahovaných z PLA-g-IAH. Radikálovou modifikací PLA došlo ke zvýšení flexibility polymerních řetězců díky objemné struktuře IAH navázané na PLA řetězci, což se projevilo poklesem teploty skelného přechodu (Tg). Zvýšený obsah amorfní fáze, hydrofilní chování, rozvětvená struktura a štěpení řetězců má pozitivní vliv na zvýšenou biodegradabilitu PLA-g-IAH v porovnání s nemodifikovanou PLA. Neradikálová degradace, probíhající v průběhu zpracování PLA, byla prokázána změnou tokových vlastností taveniny. Tento nežádoucí jev byl potlačen přídavkem tzv. “prodlužovače řetězců” obsahujícího reaktivní epoxy skupiny. Reakce mezi epoxy skupinami a karboxylovými skupinami byla potvrzena pomocí FTIR a změnou reologických vlastností PLA-g-IAH.
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.
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.
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.

National Repository of Grey Literature : 58 records found   beginprevious49 - 58  jump to record:
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3 Petrus, Jan
2 Petrus, Jiří
3 Petrus, Ján
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