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Way of assign of stereoregularity of polypropylene
Hoza, Adam ; Tocháček, Jiří (referee) ; Kratochvíla, Jan (advisor)
The purpose of this work is to evaluate and compare isotactic index value determination of polypropylene homopolymer using extraction and solubility methods. A series of nine PP samples in a powder form specified by molecular weights in the range from 29 to 154 kg/mol was investigated. The methods afforded separation of polypropylene into two portions, the soluble fraction, and the insoluble one. Extractions were carried out in a modified Kumagawa extractor. Polypropylene extracts were obtained using several organic solvents (pentane, hexane, heptane, and octane) at their boiling points. Soluble fractions were obtained by dissolving the PP sample in high boiling point solvents (xylene, decahydronaphthalene, and 1,2,3,4-tetrahydronaphthalene) and cooling the polymer solution to 23°C. All the fractions were characterized using 13C-NMR, SEC, and DSC methods. Comparison of the extraction and solubility methods showed significant differences in the amount, stereochemical structure, molecular weight, and crystallinity of soluble, and insoluble fractions.
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Influence of Ethene Addition on Ziegler-Natta Catalyst Performance in Low-pressure Propene Polymerization
Hoza, Adam ; Salajka,, Zdeněk (referee) ; Kratochvíla, Jan (advisor)
The aim of the study will be the determination of the kinetic profiles of the polymerization of propene, ethene and their mixtures with commercial Ziegler-Natta catalyst by application of two different experimental procedures. The prepared polymer material will be utilized for the SEC analysis and subsequent evaluation of the concentration of active sites. The determined molecular mass distribution curves will be further investigated by the application of the procedure, which deconvolute the overall profile on the basic Flory's distribution functions. Then the comprehensive study about character and behavior of various types of active centers in dependence on time and type of monomer will result from this investigation.
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Solubility of polypropylene in hydrocarbon solvents
Urbánková, Radka ; Kučera, Jaroslav (referee) ; Kratochvíla, Jan (advisor)
Polypropylene, on a mass-scale produced polyolefin, shows an excellent combination of end-use properties, eco-friendliness, easy recyclability, and a good processability by different technologies. Key structural parameters of polypropylene are its stereoregularity, molecular weight, and its distribution. A theoretical part of this work compiles a bibliographic search and an experimental part deals with extraction and solubility of polypropylene powder prepared on a highly active Ziegler-Natta polymerization catalyst. Extractions at a boiling point temperature of solvents (pentane - hexane - cyclohexane - hex-1-ene - benzene - heptane - octane - ethylbenzene) resulted in a progressive increase of extracted portions with temperature of extraction. Solvents used within this work were characterised by their physical properties, and steric and electronic parameters such as molecular weight, density, boiling point temperature, dipole moment, refractive index, and Hildebrand´s solubility parameter. Extraction PP at a constant temperature 36°C (boiling point of pentane) at a saturated vapour pressure in a series of hydrocarbon solvents (pentane – hexane – heptane – octane) resulted in practically the same results. Boiling octane extractable fraction at a temperature 36°C was nearly 100 % higher than fractions extracted by the other solvents. The origin of this phenomenon has not been revealed. Polypropylene solubility was determined by a complete dissolving the sample at 140°C in a series of aliphatic and aromatic solvents (pentane - hexane - cyclohexane - hex-1-ene - benzene - heptane - octane - toluene - ethylbenzene - o-xylene - m-xylene - p-xylene - decalin - chlorbenzene - 1,2-dichlorbenzene), followed by cooling the solution down to a laboratory temperature, and separating a soluble fraction, and an insoluble one. The stereoregularity of soluble fractions was characterised by a 13C NMR method, the crystallinity by a DSC method, and a molecular weight distribution by a GPC method. As a result, polypropylene solubility decreases with increasing the Hildebrand solubility parameter of the solvent that corresponds with theoretical expectations. Moreover, PP solubility correlates strongly with a refractive index, and a density of solvent.
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Temperature and Time Influence on Crystalline and Amorphous Phase Content in Polypropylene
Vilč, Ladislav ; Petrůj, Jaroslav (referee) ; Čermák,, Roman (referee) ; Kratochvíla, Jan (advisor)
is is a study of the relationship between structure, mechanical properties and relaxing behavior of the polypropylene. The structure was evaluated by the quantity the solid phase content (SPC). This was defined as mathematical result of free induction decay (FID) signal from pulsed 1H-NMR. The solid phase content is a quite new structural parameter representing the quantity for description of semi-crystalline polymers. Whereas pulsed 1H-NMR is non-destructive, accurate and repeatable, it becomes a unique tool for a description of mechanical, structural, physical-mechanical changes of polypropylene within the time and temperature. Particularly, this method registers the small changes in the time-dependant shipments during secondary crystallization with small structure changes.
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Determination of propene polymerization kinetics on Ziegler-Natta catalysts by methods of batch and Stopped-Flow polymerization performed under industrial conditions
Tvrdý, Michal ; Merna,, Jan (referee) ; Kratochvíla, Jan (advisor)
This thesis is focused on the determination of the propene polymerization kinetics on phthalate and nonphthalate diester Ziegler-Natta MgCl2-supported catalysts under the industrial conditions. The kinetic profiles were determined by various laboratory techniques for propene polymerization. For assessing the profiles were utilized batch gas and liquid polymerization modes in 2-litre and 4-litre reactors. Finally, the results were complemented with the runs performed in a unique Stopped-Flow apparatus, which allows polymerization of liquid propene at very short polymerization times. The kinetics profiles of both catalysts were determined and compared by combination of experimental data of these techniques. The basic properties of the synthesized polymeric powders were measured, such as the melt flow index, bulk density and amount of polypropene fraction soluble in cold xylene.
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Development of method thermoporosimetry polymer powders
Urbánková, Radka ; Salajka,, Zdeněk (referee) ; Kratochvíla, Jan (advisor)
Thermoporosimetry is a technique to determine small pore sizes based on melting and crystallization point depression. The temperature shift was measured by Differential Scanning Calorimetry (DSC). Development of thermoporosimetry was carried out on silica with a well-characterized narrow pore size distribution. Several parameters were studied, which a have a direct influence on melting and crystallization point depression (for example: a quality of the solvent, filling the pores with the solvent, time and frequency of centrifuging, superfluous solvent removal conditions, etc.). The optimum conditions for the thermoporosimetry method were developed using high porosity silica. The optimized experimental conditions found for silica were applied to polypropylene powder with much lower porosity. Several polypropylene powders were synthesized using different polymerization catalysts and their porosity determined. Polymer powder morphology and structure was characterized by standard methods. Powder porosity obtained by thermoporometry, gas sorption, and BET methods was compared.
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Kinetics of the Coordination Polymerization of -olefins Catalyzed by Nickel Diimine Complexes
Peleška, Jan ; Kratochvíla, Jan (referee) ; Pinkas,, Jiří (referee) ; Petrůj, Jaroslav (referee) ; Cihlář, Jaroslav (advisor)
This Ph.D. thesis is focused on kinetic study of propene and hex-1-ene coordination polymerizations initiated by complex [(2-tBuC6H4)N=C(1,8-naphtalenediyl)C=N(2-tBuC6H4)]NiBr2 activated by simple organoaluminium compounds and on product properties. In first three parts proper activators are chosen in model polymerizations. The attention is paid to the reproducibility of polymerizations and analytical methods. The fourth part is focused on propene polymerization kinetics with the aim to define optimal reaction conditions, especially polymerization temperature and time. The four part concerns also properties of polymers. The fifth and sixth parts deal with hex-1-ene polymerization kinetics conducted at various activator/initiator molar ratios and various catalytic precursor concentrations, to find out kinetic orders with respect to catalyst and cocatalyst concentration. Last part is oriented on detail mechanistic investigation of nickel diimine complexes activation process. Results of measurements in presence or absence of monomer enabled to propose new interpretation of UV-vis spectra based on concrete structures of absorbing species.
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Effect of Ethylene and Propylene on Performance of Ziegler - Natta Catalyst in Stopped - Flow Polymerization
Hoza, Adam ; Kosek, Juraj (referee) ; Petrůj, Jaroslav (referee) ; Kratochvíla, Jan (advisor)
Výzkum v této práci byl zaměřen na přípravu a charakterizaci blokových kopolymerů typu polypropylen-blok-poly(propylenu-co-ethylenu) (dále jen PP-blok-EPR). Tyto materiály jsou považovány za účinné kompatibilizátory mezi semi-krystalickou polypropylenovou (PP) matricí a amorfními doménami statistického kopolymeru propylenu a etylenu (EPR) v rázuvzdorném sekvenčním kopolymeru (ICP) a proto byl výzkum zaměřen na zkoumání vlivu přídavku blokového kopolymeru PP-blok-EPR na vlastnosti komerčního ICP. Blokové kopolymery byly připraveny za použití techniky „stopped-flow“. Pro tento účel byla zkonstruována vysokotlaká polymerační „stopped-flow“ aparatura, která umožňuje syntézu kopolymerů PP-blok-EPR za podmínek blízkých podmínkám v průmyslových reaktorech pro výrobu komerčních ICP materiálů. Aparatura umožňuje vyrábět PP-blok-EPR polymer v množství dostačující na jeho charakterizaci a následnou přípravu směsí s komerčním ICP. Velmi krátké polymerační časy (obvykle kolem 0.2 s) kterých bylo dosaženo v kapilárním reaktoru aparatury „stopped-flow“ zajišťuje, že aktivní centra Ziglorova-Nattova katalyzátoru produkují polymer řetězce skládající se z bloku semikrystalického polypropylenu a bloku amorfního EPR kopolymeru. Takovéto molekuly jsou v literatuře popsány jako „skutečné blokové kopolymery PP-blok-EPR“. Kopolymery syntetizované v aparatuře „stopped-flow“ byly frakcionovány preparativní TREF (Temperature Rising Elution Fractionation) metodou a získané frakce byly následně analyzovány pomocí DSC, 13C-NMR a GPC/SEC. Tyto analýzy odhalily přítomnost amorfního EPR ve vysoce krystalické frakci (100-140 °C). Toto zjištění potvrdilo, že významná část polymerních řetězců, připravených v aparatuře „stopped-flow“ jsou blokové kopolymery skládající se z bloku semikrystalického PP homopolymeru a bloku amorfního EPR kopolymeru v jednom polymerním řetězci. Kopolymery získané metodou „stopped-flow" byly v tavenině smíchány s komerčním rázuvdorným kopolymerem ICP. U takto připravených směsí byly vyhodnoceny mechanické vlastnosti, DTMA a reologické vlastnosti a výsledky byly srovnány s vlastmi původního komerčního ICP kopolymeru. Dále byly studovány rozdíly v morfologii a umístění EPR domén v matrici PP prostřednictvím SEM. Zřetelný vliv kopolymeru PP-blok-EPR na vlastnosti ICP byl pozorován zejména v morfologických změnách EPR domén dispergovaných v PP matrici. Tyto změny mají pozitivní vliv na rovnováhu mezi modulem v ohybu a rázovou pevností ICP materiálu. Vliv kopolymeru PP-blok-EPR na reologické vlastnosti ICP byl nevýznamný. Podobně také v případě DTMA nebyl pozorován významný vliv kopolymeru PP-blok-EPR na vlastnosti ICP.
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Determination of propene polymerization kinetics on Ziegler-Natta catalysts by methods of batch and Stopped-Flow polymerization performed under industrial conditions
Tvrdý, Michal ; Merna,, Jan (referee) ; Kratochvíla, Jan (advisor)
This thesis is focused on the determination of the propene polymerization kinetics on phthalate and nonphthalate diester Ziegler-Natta MgCl2-supported catalysts under the industrial conditions. The kinetic profiles were determined by various laboratory techniques for propene polymerization. For assessing the profiles were utilized batch gas and liquid polymerization modes in 2-litre and 4-litre reactors. Finally, the results were complemented with the runs performed in a unique Stopped-Flow apparatus, which allows polymerization of liquid propene at very short polymerization times. The kinetics profiles of both catalysts were determined and compared by combination of experimental data of these techniques. The basic properties of the synthesized polymeric powders were measured, such as the melt flow index, bulk density and amount of polypropene fraction soluble in cold xylene.
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