|
|
Effect of Ethylene and Propylene on Performance of Ziegler - Natta Catalyst in Stopped - Flow Polymerization
Hoza, Adam ; Kosek, Juraj (oponent) ; Petrůj, Jaroslav (oponent) ; Kratochvíla, Jan (vedoucí práce)
The research presented in this thesis was focused on preparation and characterization of polypropylene-block-poly(propylene-co-ethylene (hereinafter referred to also as real PP-block-EPR),. These materials are considered to be efficient compatibilizers between semi-crystalline polypropylene (PP) matrix and amorphous ethylene/propylene rubber (EPR) domains in impact-resistant polypropylene copolymers (ICP), thus also an effect of prepared PP-block-EPR copolymers on properties of commercial ICP materials was investigated. The unique PP-block-EPR copolymers were prepared by using the „stopped-flow” technique. For this purpose a high-pressure "stopped-flow" polymerization apparatus was constructed. This apparatus allowed synthesis of PP-block-EPR copolymers under conditions comparable to conditions applied in industrial reactors for production of standard ICP materials. The apparatus also enabled to produce sufficient amounts of materials for characterizing and subsequent blending with ICP. Very short polymerization times (typically around 0.2 s) applied in "stopped-flow" capillary reactors ensured that active sites of a Ziegler-Natta catalyst produced polymer chains consisting of a block of semi-crystalline polypropylene (PP) and a block of amorphous ethylene/propylene random copolymer (EPR). Such macromolecules are described in literature as “real PP-block-EPR copolymer”. Copolymer materials synthesized in the "stopped-flow" apparatus were fractionated by preparative means of Temperature Rising Elution Fractionation (TREF). The obtained fractions were subsequently analyzed by DSC, 13C-NMR and GPC/SEC methods. These analyses revealed the presence of amorphous EPR, also in high crystalline fraction (100 140 °C). This finding confirmed that a noticeable portion of polymer chains, produced in the stopped-flow polymerization, were real block copolymers consisting of block of semi-crystalline PP homopolymer and block of amorphous EPR copolymer in one polymer chain. The prepared samples were blended in melt with a commercial ICP material. Mechanical properties, DTMA and oscillation rheology were employed on the prepared blends and the results compared with properties of original ICP copolymer. Furthermore, the differences in EPR domains morphology and location in PP matrix were studied by SEM. An obvious influence of PP-block-EPR copolymer on ICP properties was observed mainly in morphological changes of EPR domains dispersed in the PP matrix. These changes showed a positive influence on the balance between flexural modulus and impact strength of ICP material. The influence of PP-block-EPR copolymer on ICP rheology was insignificant. Similarly, also in the case of DTMA no obvious influence of PP-block-EPR copolymer on dynamic-mechanical properties of ICP was observed.
|
|
|
Control of the morphology of biodegradable polymer blends
Ostafińska, Aleksandra ; Šlouf, Miroslav (vedoucí práce) ; Kosek, Juraj (oponent) ; Vohlídal, Jiří (oponent)
Tato disertační práce s názvem »Řízení morfologie směsí biodegradovatelných polymerů« vznikla v rámci grantového projektu »Multifázové biodegradovatelná polymerní systémy« a reprezentuje nový směr výzkumu v Oddělení morfologie a reologie polymerních materiálů na Ústavu makromolekulární chemie. Hlavní myšlenkou práce bylo využít naše rozsáhlé zkušenosti z oblasti zobrazování a řízení morfologie směsí syntetických polymerů, a to na analogickém poli morfologie biopolymerů. Pro výzkum jsme zvolili tři běžné, široce využívané a poměrně levné biopolymery: škrob, poly(mléčnou kyselinu) a poly(ϵ- kaprolakton). Cílem výzkumu bylo prověřit, jakým způsobem lze zlepšit užitné vlastnosti jejich směsí pomocí předem promyšlené, cílené a reprodukovatelné optimalizace jejich morfologie. Těsná souvislost mezi morfologií (fázovou strukturou, nadmolekulární strukturou) a vlastnostmi polymerních směsí (např. tahovými vlastnostmi, rychlostí biodegradace, propustností pro plyny aj.) je v polymerní vědě obecně přijímaným faktem. V našem případě ukázal průzkum literatury a předběžné experimenty, že existují dva systémy, u nichž by cílené řízení morfologie mohlo výrazně zlepšit užitné vlastnosti: (i) systémy PLA/PCL/TiX (kde PLA = poly(mléčná kyselina), PCL = poly(ϵ-kaprolakton), TiX = částice na bázi TiO2) a (ii) systémy...
|
|
|
Control of the morphology of biodegradable polymer blends
Ostafińska, Aleksandra ; Šlouf, Miroslav (vedoucí práce) ; Kosek, Juraj (oponent) ; Vohlídal, Jiří (oponent)
Tato disertační práce s názvem »Řízení morfologie směsí biodegradovatelných polymerů« vznikla v rámci grantového projektu »Multifázové biodegradovatelná polymerní systémy« a reprezentuje nový směr výzkumu v Oddělení morfologie a reologie polymerních materiálů na Ústavu makromolekulární chemie. Hlavní myšlenkou práce bylo využít naše rozsáhlé zkušenosti z oblasti zobrazování a řízení morfologie směsí syntetických polymerů, a to na analogickém poli morfologie biopolymerů. Pro výzkum jsme zvolili tři běžné, široce využívané a poměrně levné biopolymery: škrob, poly(mléčnou kyselinu) a poly(ϵ- kaprolakton). Cílem výzkumu bylo prověřit, jakým způsobem lze zlepšit užitné vlastnosti jejich směsí pomocí předem promyšlené, cílené a reprodukovatelné optimalizace jejich morfologie. Těsná souvislost mezi morfologií (fázovou strukturou, nadmolekulární strukturou) a vlastnostmi polymerních směsí (např. tahovými vlastnostmi, rychlostí biodegradace, propustností pro plyny aj.) je v polymerní vědě obecně přijímaným faktem. V našem případě ukázal průzkum literatury a předběžné experimenty, že existují dva systémy, u nichž by cílené řízení morfologie mohlo výrazně zlepšit užitné vlastnosti: (i) systémy PLA/PCL/TiX (kde PLA = poly(mléčná kyselina), PCL = poly(ϵ-kaprolakton), TiX = částice na bázi TiO2) a (ii) systémy...
|
|
|
Effect of Ethylene and Propylene on Performance of Ziegler - Natta Catalyst in Stopped - Flow Polymerization
Hoza, Adam ; Kosek, Juraj (oponent) ; Petrůj, Jaroslav (oponent) ; Kratochvíla, Jan (vedoucí práce)
The research presented in this thesis was focused on preparation and characterization of polypropylene-block-poly(propylene-co-ethylene (hereinafter referred to also as real PP-block-EPR),. These materials are considered to be efficient compatibilizers between semi-crystalline polypropylene (PP) matrix and amorphous ethylene/propylene rubber (EPR) domains in impact-resistant polypropylene copolymers (ICP), thus also an effect of prepared PP-block-EPR copolymers on properties of commercial ICP materials was investigated. The unique PP-block-EPR copolymers were prepared by using the „stopped-flow” technique. For this purpose a high-pressure "stopped-flow" polymerization apparatus was constructed. This apparatus allowed synthesis of PP-block-EPR copolymers under conditions comparable to conditions applied in industrial reactors for production of standard ICP materials. The apparatus also enabled to produce sufficient amounts of materials for characterizing and subsequent blending with ICP. Very short polymerization times (typically around 0.2 s) applied in "stopped-flow" capillary reactors ensured that active sites of a Ziegler-Natta catalyst produced polymer chains consisting of a block of semi-crystalline polypropylene (PP) and a block of amorphous ethylene/propylene random copolymer (EPR). Such macromolecules are described in literature as “real PP-block-EPR copolymer”. Copolymer materials synthesized in the "stopped-flow" apparatus were fractionated by preparative means of Temperature Rising Elution Fractionation (TREF). The obtained fractions were subsequently analyzed by DSC, 13C-NMR and GPC/SEC methods. These analyses revealed the presence of amorphous EPR, also in high crystalline fraction (100 140 °C). This finding confirmed that a noticeable portion of polymer chains, produced in the stopped-flow polymerization, were real block copolymers consisting of block of semi-crystalline PP homopolymer and block of amorphous EPR copolymer in one polymer chain. The prepared samples were blended in melt with a commercial ICP material. Mechanical properties, DTMA and oscillation rheology were employed on the prepared blends and the results compared with properties of original ICP copolymer. Furthermore, the differences in EPR domains morphology and location in PP matrix were studied by SEM. An obvious influence of PP-block-EPR copolymer on ICP properties was observed mainly in morphological changes of EPR domains dispersed in the PP matrix. These changes showed a positive influence on the balance between flexural modulus and impact strength of ICP material. The influence of PP-block-EPR copolymer on ICP rheology was insignificant. Similarly, also in the case of DTMA no obvious influence of PP-block-EPR copolymer on dynamic-mechanical properties of ICP was observed.
|
host ::
RSS.