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Imidation of cyclic anhydrides and modified polyolefins
Šimonek, Michal ; Petrůj, Jaroslav (referee) ; Kučera, František (advisor)
The main focus of the presented bachelor’s thesis is on the reaction pathway that leads to the formation of cyclic imides and utilizing imidation as a way to modify polyolefins. The theoretical part serves as a summary of relevant information concerning the formation of imides, functionalization of polyolefins via radical-induced grafting, and exploitation of reactions between anhydride-modified polyolefins and various amines. The specificity of amic acid formation was tested via reactions of succinic acid and ammonia in different molar ratios. Suitability of succinamic acid and its ammonium salt to give succinimide was evaluated. Similarly, N-substituted succinamic acid and succinimide were prepared from commercial amine, Elastamine RE1-2007, and succinic acid. Imide modified polyolefins were prepared firstly by a reaction in a solution of toluene, secondly in the melt in Brabender laboratory kneader at 60 and 120 rpm respectively, reaction temperature of 190 °C and reaction time of 16 minutes. The presence of expected groups in all samples was determined by FT-IR spectrometry. Modified polyolefins from the reaction in a solution were analysed by DSC and TGA to determine suitable reaction temperature for experiments in the melt. Kneader torque traces were examined to characterize mixing during reactions in the melt state.
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Electrical behaviour of polymeric composites with expanded graphite
Šimonek, Michal ; Petruš, Josef (referee) ; Kučera, František (advisor)
Electrically conductive thermoplastic composites made from graphene nanoplatelets or graphene precursors are a promising branch of new functional materials. Graphene nanocomposites were prepared via processing in an internal mixer from four extrusion grade polyethylenes (PE) and expanded graphite (EG). As a method of possible improvement of EG dispersion, compounding in presence of various compatibilizers is examined. Melt compounding was performed for 10 min at 200 °C and 60 rpm. The electrical conductivity of compression-molded samples was determined from a current voltage characteristic or direct resistance measurement. Composite morphology was characterized by scanning electron microscopy. Depending on the PE matrix and compatibilizer structure, different electrical conductivities and morphologies were observed, which corresponded in agreement with either percolation theory or the random-resistor network of Miller and Abrahams models. Substantial reduction of percolation threshold was achieved in compatibilized ultra-low density polyethylene where percolation occurred at 3,92 % vol.
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Electrical behaviour of polymeric composites with expanded graphite
Šimonek, Michal ; Petruš, Josef (referee) ; Kučera, František (advisor)
Electrically conductive thermoplastic composites made from graphene nanoplatelets or graphene precursors are a promising branch of new functional materials. Graphene nanocomposites were prepared via processing in an internal mixer from four extrusion grade polyethylenes (PE) and expanded graphite (EG). As a method of possible improvement of EG dispersion, compounding in presence of various compatibilizers is examined. Melt compounding was performed for 10 min at 200 °C and 60 rpm. The electrical conductivity of compression-molded samples was determined from a current voltage characteristic or direct resistance measurement. Composite morphology was characterized by scanning electron microscopy. Depending on the PE matrix and compatibilizer structure, different electrical conductivities and morphologies were observed, which corresponded in agreement with either percolation theory or the random-resistor network of Miller and Abrahams models. Substantial reduction of percolation threshold was achieved in compatibilized ultra-low density polyethylene where percolation occurred at 3,92 % vol.
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Imidation of cyclic anhydrides and modified polyolefins
Šimonek, Michal ; Petrůj, Jaroslav (referee) ; Kučera, František (advisor)
The main focus of the presented bachelor’s thesis is on the reaction pathway that leads to the formation of cyclic imides and utilizing imidation as a way to modify polyolefins. The theoretical part serves as a summary of relevant information concerning the formation of imides, functionalization of polyolefins via radical-induced grafting, and exploitation of reactions between anhydride-modified polyolefins and various amines. The specificity of amic acid formation was tested via reactions of succinic acid and ammonia in different molar ratios. Suitability of succinamic acid and its ammonium salt to give succinimide was evaluated. Similarly, N-substituted succinamic acid and succinimide were prepared from commercial amine, Elastamine RE1-2007, and succinic acid. Imide modified polyolefins were prepared firstly by a reaction in a solution of toluene, secondly in the melt in Brabender laboratory kneader at 60 and 120 rpm respectively, reaction temperature of 190 °C and reaction time of 16 minutes. The presence of expected groups in all samples was determined by FT-IR spectrometry. Modified polyolefins from the reaction in a solution were analysed by DSC and TGA to determine suitable reaction temperature for experiments in the melt. Kneader torque traces were examined to characterize mixing during reactions in the melt state.
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