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Thermomechanical response of polymer nanocomposites with preparation protocol controlled nanoparticle dispersion
Ondreáš, František ; Chodák,, Ivan (oponent) ; Matějka,, Libor (oponent) ; Jančář, Josef (vedoucí práce)
This thesis is focused on a fundamental investigation of nanoparticle self-assembly in polymer liquids and on properties of the prepared polymer nanocomposites with controlled nanoparticle dispersion. Despite recent progress in understanding polymer nanocomposites, there are still unfilled gaps in the fundamental knowledge of relaxation phenomena and mechanical properties of various nanostructures that would provide key information for designing hierarchical or multidomain nanocomposites processable by additive manufacturing technologies. The emphasis was put on the investigation of the preparation protocol influence on the final dispersion state, preparation of various nanostructures – individually dispersed NPs, chain bound clusters, and contact aggregates at a constant composition, and determination of their relaxation and mechanical properties. Moreover, nanoparticles were utilized as “probes” in polymer matrix that affect the segmental ordering and the relaxation dynamics of polymer chains. This approach can help to derive the relationship between the nano scale segmental dynamics and macro scale mechanical properties of polymer glasses. It is a challenging fundamental scientific problem with an extreme technological importance. Non-grafted ceramic nanoparticles and polymer glasses were used to avoid the focus to deflect from the study of the nanoparticle–polymer interaction influence towards the influence of the graft–polymer interaction or the altered crystalline structure. A thorough investigation was performed for the PMMA/SiO2 model system and subsequently broadened to systems with different matrices (PC and PS) and nanoparticles (ZnO2 and Fe2O3) in order to generalize the obtained results. Nanostructure, volume fraction, and composition dependences of relaxation – glass transition temperature, reptation time, plateau modulus, number of entanglements, and mechanical properties – yield stress, yield drop, elastic modulus, strain hardening modulus, and creep response were determined. Achieved results were interpreted by means of the recent models. The determined relaxational and mechanical properties were connected to provide information about the molecular processes responsible for the mechanical response of the polymer nanocomposites.
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Thermomechanical response of polymer nanocomposites with preparation protocol controlled nanoparticle dispersion
Ondreáš, František ; Chodák,, Ivan (oponent) ; Matějka,, Libor (oponent) ; Jančář, Josef (vedoucí práce)
This thesis is focused on a fundamental investigation of nanoparticle self-assembly in polymer liquids and on properties of the prepared polymer nanocomposites with controlled nanoparticle dispersion. Despite recent progress in understanding polymer nanocomposites, there are still unfilled gaps in the fundamental knowledge of relaxation phenomena and mechanical properties of various nanostructures that would provide key information for designing hierarchical or multidomain nanocomposites processable by additive manufacturing technologies. The emphasis was put on the investigation of the preparation protocol influence on the final dispersion state, preparation of various nanostructures – individually dispersed NPs, chain bound clusters, and contact aggregates at a constant composition, and determination of their relaxation and mechanical properties. Moreover, nanoparticles were utilized as “probes” in polymer matrix that affect the segmental ordering and the relaxation dynamics of polymer chains. This approach can help to derive the relationship between the nano scale segmental dynamics and macro scale mechanical properties of polymer glasses. It is a challenging fundamental scientific problem with an extreme technological importance. Non-grafted ceramic nanoparticles and polymer glasses were used to avoid the focus to deflect from the study of the nanoparticle–polymer interaction influence towards the influence of the graft–polymer interaction or the altered crystalline structure. A thorough investigation was performed for the PMMA/SiO2 model system and subsequently broadened to systems with different matrices (PC and PS) and nanoparticles (ZnO2 and Fe2O3) in order to generalize the obtained results. Nanostructure, volume fraction, and composition dependences of relaxation – glass transition temperature, reptation time, plateau modulus, number of entanglements, and mechanical properties – yield stress, yield drop, elastic modulus, strain hardening modulus, and creep response were determined. Achieved results were interpreted by means of the recent models. The determined relaxational and mechanical properties were connected to provide information about the molecular processes responsible for the mechanical response of the polymer nanocomposites.
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