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Research of effective use and activation of activ concrete additions
Mikhailova, Olesia ; Ťažký, Tomáš (referee) ; Hela, Rudolf (advisor)
The theoretical part describes the admixtures that are used in cement replacement. Here also summarizes the findings on the influence of granulomentry, grain shape and fineness of admixtures on the density of the cement matrix. The practical part is experimentally verified the influence of fineness admixtures and grain size on the mechanical properties of concrete. Also, the rheological properties of cement are compared with admixtures depending on the type and dosage and time.
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Technical and economic comparison of usability of different types of cements
Kováč, Michal ; Ťažký, Tomáš (referee) ; Hela, Rudolf (advisor)
This bachelor thesis deals with comparison of properties of different types of cements. The theoretical part is devoted to the distribution of cements, their composition and production. Various properties of cements are detected and compared in the practical part. Furthermore, concrete formulas are created which are also mixed and tested. Finally, the proposed area for the test cements and economic evaluation per 1 m3 of concrete mix.
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Heterogeneous Radical Modification of Polypropylene
Brňák, Matúš ; Petruš, Josef (referee) ; Kučera, František (advisor)
The diploma thesis deals with the heterogeneous technique of preparation of grafted polypropylene g maleic anhydride (PP-g-MAH). The knowledge of the course of the reaction and its impact on the PP grafting process are summarized in the theoretical part. The preparation of the grafted PP was carried out in a fluidized polymerization reactor at 115 °C, speed of mixing 210 rpm, reaction time 60 min and pressure 6 bar. The amount of grafted MAH was monitored by using a MAH concentration 3 and 5 wt% and an initiator concentration 0.25; 0.5; 1; and 1.5 wt%. Modification efficiency was compared by using 3 types of PP with different particle morphology and specific surface area. By creating the theoretical model, the maximum surface concentration of MAH was calculated and compared with experimental data. Characterization of PP materials was performed by Electron Scanning Microscopy (SEM), Differential Scanning Calorimetry (DSC) and particle surface analysis by BET. Quantitative analysis of grafted MAH was determined by FTIR spectroscopy and acid-base titration.
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The Influence of Fines on Pore System of Concrete
Elfmarková, Veronika ; Smolka, Hynek (referee) ; Hela, Rudolf (advisor)
Literature does not provide a satisfactory answer to maximum and minimum particle size or the particle size of the mortar phase especially for optimal porosity of concrete. To overcome the shortcomings of the design methods were thought to design a new method for design of concrete mix. This idea is based on a complex analysis of powder materials (determination of granular properties, shape factor of fillers, porosity, packing of powder materials, surface area, etc.) and subsequently to assess the influence to pore system of concrete and physical and mechanical properties in hardened state of concrete. In this work are presented and analyzed two types of fillers – fly ash and limestone dust.
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Functionalized hyper-cross-linked porous polyacetylenes
Havelková, Lucie
An atom-economic one-step chain-growth coordination homopolymerization providing high yields of functionalized hyper-cross-linked polyacetylenes with permanent micro/mesoporous texture and specific surface area up to 1062 m2 /g was introduced and optimized. Substituted 1,3-diethynylbenzenes served as monomers simultaneously providing functionalization and hyper-cross-linking of the networks. The homopolymerization was compatible with the heteroatom groups of the monomers and allowed to prepare polyacetylene networks with the wide spectrum of univalent functional groups: -F, -Cl, -Br, -NO2, -COOCH3, -CH2OH, -COOH and -CH=O decorating the aromatic segments of the networks in a high extent (7.87 mmol/g). A novel two-step synthesis of functionalized hyper-cross-linked polyacetylenes was introduced combining chain-growth coordination polymerization of acetylenic monomers and covalent templating using acetal and Schiff base protecting groups. By postpolymerization hydrolytic removal of the protecting segments from the primary networks, the networks with a high content (up to 9.61 mmol/g) of univalent functional groups -CH2OH, -CH=O and -NH2 were prepared. These groups were placed either on the cross-linking or linear (aromatic and aliphatic) network segments, even in the vicinity of the main...
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Functionalized hyper-cross-linked porous polyacetylenes
Havelková, Lucie ; Sedláček, Jan (advisor) ; Brožek, Jiří (referee) ; Balcar, Hynek (referee)
An atom-economic one-step chain-growth coordination homopolymerization providing high yields of functionalized hyper-cross-linked polyacetylenes with permanent micro/mesoporous texture and specific surface area up to 1062 m2 /g was introduced and optimized. Substituted 1,3-diethynylbenzenes served as monomers simultaneously providing functionalization and hyper-cross-linking of the networks. The homopolymerization was compatible with the heteroatom groups of the monomers and allowed to prepare polyacetylene networks with the wide spectrum of univalent functional groups: -F, -Cl, -Br, -NO2, -COOCH3, -CH2OH, -COOH and -CH=O decorating the aromatic segments of the networks in a high extent (7.87 mmol/g). A novel two-step synthesis of functionalized hyper-cross-linked polyacetylenes was introduced combining chain-growth coordination polymerization of acetylenic monomers and covalent templating using acetal and Schiff base protecting groups. By postpolymerization hydrolytic removal of the protecting segments from the primary networks, the networks with a high content (up to 9.61 mmol/g) of univalent functional groups -CH2OH, -CH=O and -NH2 were prepared. These groups were placed either on the cross-linking or linear (aromatic and aliphatic) network segments, even in the vicinity of the main...
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Porous polymer networks prepared from ethynylpyridines
Titlová, Štěpánka ; Sedláček, Jan (advisor) ; Sedláček, Ondřej (referee)
Series of new micro/mesoporous polymer networks with high content of pyridine segments was prepared. For the preparation were used ethynylpyridine type of monomers which were successfully homopolymerized and copolymerized with hydrocarbon diethynylarenes by chain-growth coordination polymerization catalyzed with [Rh(NBD)acac] complex. Polymerizations provided polyacetylene networks with main chains densely cross- linked by pyridine or arylene links. Prepared pyridine networks showed specific surface area SBET from 308 m2 /g to 923 m2 /g and variable content of pyridine segments in an interval from 3,27 mmol/g to 7,86 mmol/g. In networks, pyridine segments made part of interchain links or side groups. Networks with pyridine segments were successfully quaternized by heterogeneous postpolymerization reaction with bromoethane to form well covalently defined networks containing N-ethylpyridinium segments. Quaternized networks containing pyridinim segments in amount from 2,41 mmol/g to 4,24 mmol/g had preserved micro/mesoporous texture with values of SBET from 331 m2 /g to 592 m2 /g. Polyacetylene networks with N-ethylpyridinium segments were prepared also by catalyst-free (spontaneous) quaternization polymerization of diethylpyridines. These networks were worse covalently defined and had proved lower...
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Functionalized microporous polymer networks prepared from ethynylarenes
Stahlová, Sabina ; Sedláček, Jan (advisor) ; Etrych, Tomáš (referee) ; Červený, Libor (referee)
The preparation of a new group of functionalized conjugated polymer networks has been described based on spontaneous quaternization polymerization of ethynylpyridines with bis(bromomethyl)arenes. The networks consisted of polyacetylene chains with pyridyl and pyridiniumyl pendants cross-linked with -CH2(arylene)CH2- links. The variation of the ratio of monomer and quaternization agent in the feed modified the ratio of pyridyl and pyridiniumyl groups in the networks (pyridyl/pyridiniumyl ratios from 0 to 1.32). The networks did not exhibit a permanent microporosity that could be confirmed by nitrogen adsorption at 77 K. Nevertheless, all networks were active in capture of CO2 at 293 K (up to 0.73 mmol CO2/g, 750 Torr). It has been hypothesized that CO2 capture reflected formation of a temporary porous texture of the networks through conformational changes of the network segments enabled by the segments mobility at room temperature. The preparation of functionalized conjugated polymer networks with permanent micro/mesoporosity (SBET up to 667 m2 /g) has been described that was based on chain coordination copolymerization of acetylenic monomers. The copolymerization of 1,4-diethynylbenzene or 4,4'-diethynylbiphenyl with mono or diethynylbenzenes bearing NO2 or CH2OH groups has been demonstrated as...
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