• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 19
  • 3
  • 2
  • Tagged with
  • 23
  • 23
  • 23
  • 17
  • 17
  • 13
  • 7
  • 7
  • 6
  • 6
  • 6
  • 5
  • 5
  • 5
  • 4
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Compatibilisation de matières plastiques en mélange issues de déchets d’équipements électriques et électroniques en vue de leur valorisation par recyclage mécanique / Compatibilization of mixed plastics from waste electrical and electronic equipment for recovery by mechanical recycling

Maris, Joachim 16 May 2018 (has links)
Le recyclage des déchets plastiques issus des déchets d'équipements électriques et électroniques (D3E) est devenu un enjeu majeur de nos sociétés afin de limiter leur impact environnemental. Le recyclage mécanique apparaît aujourd’hui comme une solution mature industriellement et adaptée pour produire de matières premières de recyclage (MPR). L’objectif de cette thèse est la compatibilisation de mélange de plastiques issus de la filière de tri des D3E en vue de leur valorisation par recyclage mécanique. La caractérisation des mélanges D3E par des analyses FT-IR, fluorescence-X, ATG et DSC a montré qu’il s’agissait de mélanges complexes contenant majoritairement des polymères styréniques et des polyoléfines et de faible pourcentage de PVC, PMMA, PC… Ces mélanges, mis en œuvre, présentent des propriétés mécaniques très faibles par rapport aux polymères techniques et de commodité. Ces résultats ont démontré la nécessité d’une compatibilisation de ces D3E en vue de leur transformation en MPR. Au vu de la complexité des mélanges, la compatibilisation in situ à l’aide de réactions radicalaires est apparue particulièrement prometteuse. Une première approche a consisté à générer les radicaux par irradiation puis, en deuxième approche, par ajout d’amorceurs chimiques. Ces deux approches n’ont pas produit d’améliorations significatives des propriétés. Suite à ces résultats, des essais de compatibilisation par ajout de copolymères ont été entrepris, conduisant à une amélioration importante des propriétés mécaniques. La réalisation de prototypes techniques, à partir de MPR compatibilisés, a été validée et permet de démontrer leur potentiel technique. / The recycling of the plastics from waste electrical and electronic equipment (WEEE) has attracted great attention recently for environmental reasons. Mechanical recycling has emerged as the most economical, as well as the most energetic and ecologically efficient option. The aim of this work is the mechanical recycling of WEEE mixed plastic waste (MPW) streams. First, MPW composition has been evaluated by FT-IR and X-ray fluorescence spectroscopies, and ATG and DSC analyses. MPW are complex blend composed of thermoplastics, mainly styrenic polymers (ABS, HIPS, PS) and polyolefins. The remaining were other thermoplastics as PVC, PE, PMMA, PC…. After processing, these mixtures show very low mechanical properties compared to commodity and engineering thermoplastics. These results demonstrated that compatibilization is necessary to transform these D3E into secondary raw materials (SRM). In situ compatibilization using radical reactions appeared to be an attractive solution. Two pathways have been studied to generate the radicals, firstly, by electron beam radiation and, secondly, by adding chemical initiators. These two approaches didn’t show any substantial improvement in mechanical properties. Following these results, compatibilization by addition of reactive and non-reactive commercial copolymers were undertaken, leading to a significant improvement in mechanical properties. The production of technical prototypes and 3D printing wires from compatibilized SRM has been validated and allows considering an industrial development.
12

Specifický cementový kompozit na bázi druhotných surovin s důrazem na trvanlivost / Specific cement composite based on secondary raw materials with emphasis on durability

Figala, Petr January 2018 (has links)
Nowadays the attention to the utilization of secondary raw materials as a component of building materials is being paid to in the Czech Republic and in the world. This thesis deals with possibilities of using secondary raw materials as partial cement substitutes in industrial floors. The aim of this thesis is to verify the influence of cement substitution amount with secondary raw materials and their fineness of grinding on the properties of the floor surface in time and on its structure. On the basis of the acquired knowledge, the influence of the pre-treatment of the secondary raw material on the properties of the floor ceiling with an emphasis on the economic aspect was assessed. After evaluating the results, some substitution of cement in the floor screed with secondary raw materials is beneficial. The significant influence of more intensive milling of the floor screeds base on the parameters of the final floor screed was not confirmed. It seems, that it is possible to achieve very good results even when using secondary raw materials with a lower percentage of fine particles. This brings together the economic benefits of lowering the cost of a lower dose of expensive cement by using cheaper secondary raw materials, because pre-treatment of such materials does not require the use of a large amount of energy.
13

Vývoj chemicky odolné stříkané směsi / Development of chemically resistant sprayed mixture

Hermann, Radek January 2019 (has links)
Production wastes for which a direct use in another production is found become secondary raw materials. There are several institutions in Czech Republic and in the world, which are currently dealing with the issue. This thesis deals with the issue of cementitious spray concrete mixtures and deals with the possibilities of using secondary raw materials and waste from production as partial replacement of binder and filler in these mixtures. The aim of this theses is to optimize the composition of additives in the recipe of the commercially produced pray mixture and to verify the influence of the degree of substitution of binder or filler by secondary raw materials on its physical-mechanical properties. The aim is to maintain or increase these properties while substituting the binder and filler as much as possible. After the evaluation of results, it is possible to say, by suitable optimization of the additives it is possible to achieve a significant improvement of the physical-mechanical properties of the mass and furthermore, from the results of this thesis follows, that by substitution of 100% fine filler in combination with substitution of 30% binder it is possible to maintain or increase the physical-mechanical properties after 28 days of curing and to significantly increase these properties after 90 days of curing. The results of this thesis are also related to the reduction of economic impact on production of the spray mixture, mainly due to the use of secondary raw materials.
14

Hodnocení ekonomické situace zvolené korporace a návrhy na její zlepšení / Assessment of the Economic Situation in Selected Corporation and Proposals for its Improvement

Polášková, Viktorie January 2019 (has links)
The diploma thesis is focused on the analysis of a chosen company that deals with waste treatment and how to use it further. The overall company´s situation is evaluated thanks to the chosen analytical methods which investigate inner and outer company´s surroundings. The suggestions and recommendations leading to the improvement of the observed situation are formulated on the basis of the analyses.
15

Efektivní návrh a provoz recyklační linky jako prvek komplexního odpadového řetězce / Effective proposal and operation of recycling line as an element in waste management

Dufka, Martin January 2019 (has links)
This master thesis deals with the current situation of waste management of material usable municipal waste with focus on various fractions of plastics. The theoretical part summarises the legislation of waste treatment, also contains an analysis of the current situation of waste management in the Czech Republic and comparison the situation in the European Union. In the next part of thesis are described basic fractions of plastics and their properties. There are mentioned the current problems with plastics processing and the risks of leakage to the environment. Furthermore, a complex chain of plastic waste reprocessing is described, since the inception of plastics waste to the manufacture of products made from recycled plastics. The most attention is paid to the discription of recycling plant, where the output material from sorting lines is reprocessed into a secondary material in the form of flakes or granules. Also this part is focused on the technology of recycling line and the individual devices are described. In the practical part of the thesis is created techno-economic model of recycling line with the aim of its use for balance calculations of recycling and also economic evaluation. As a part of the model was made a market research of secondary raw materials with a focus on price development. Subsequetly, sensitivity analyzes of selected parameters are applied to the model and the impact of scenarios on the economic results are evaluated.
16

Vývoj nového chemicky odolného nátěrového systému s obsahem druhotných surovin / Development of new chemically resistant coating system containing secondary raw materials

Stodolovská, Šárka January 2021 (has links)
New types of highly chemically resistant coating systems, primarily designed for concrete and metal substrates are designed and experimentally verified within the diploma thesis. Secondary raw materials, including solidified hazardous waste, are used as microfillers. The developed coating system is solved in two quality levels – PREMIUM and ECOLOGY. The level of PREMIUM is mainly designed for environments where extreme chemical stress is occurring. The polymer coating systém ECOLOGY can be used in environments where aggressive chemical media also act, however the ecological foot of the input raw materials is most important. The diploma thesis is dealing with current issues in the practice and it is the part of the research project.
17

Ověření různých druhů popílků pro výrobu umělého kameniva / Verification of different types of fly ash for production of artificial aggregate

Zahálka, Milan January 2014 (has links)
Diploma thesis gives an overview of artificial lightweight aggregates based on fly ash. Fly ash such as the residues of coal burning is currently one of the most used secondary raw materials for new building materials for research papers. The results shows that the secondary energy products are not just fully substitute the primary component, but in many cases improves the final properties of building products. Wide complex of fly ashes not only from domestic sources was tested and it`s main properties important for it`s further application was determined. Laboratory production of artificial aggregates based on fly ash made by sintering and also by cold bonding and following manufacture of artificial fly ash aggregates in technological conditions are also solved. The thesis is simultaneously concentrate on review of the suitability of fly ash aggregates in lightweight concrete.It was found that the highest quality fly ash for the production of sintered fly ash aggregate is fly ash and FBC ash is the best for the production of cold bonded aggregates. It was also verified that both types of aggregates are applicable to lightweight concrete class LC 20/22. The vast majority of manufactured aggregates is suitable for the production of lightweight concrete class LC 30/33. It was demonstrated that the sintered fly ash aggregates can be also used for high strength lightweight concrete class LC 50/55. Tests have also verified that all tested fly ashes and products produced from them meet the requirements of legislation on environment.
18

Vývoj speciálních ochranných hmot pro hygienicky čisté provozy / Development of special protective materials for hygienically clean areas

Seják, František January 2017 (has links)
The diploma thesis deals with the development of special protective materials for hygienically clean plants. The main aim of the thesis is to develop a special protective material on a polymer base usable for hygienically clean industrial plants in two quality levels (economy and premium). The first of the developed polymer protective materials is physiologically harmless (economy) – suitable for contact with eatables. Second, premium material is antibacterial, especially suitable as a floor coating in hospitals, kitchens, sanitary facilities, schools and kindergarten etc. A partial aim is the replacement currently used primary raw materials as fillers by suitable secondary raw material.
19

Pokročilý materiál pro zřízení vrstvy zemního tělesa na bázi druhotných surovin / Advanced material based on secondary raw materials for construction of subgrade layer

Hrubý, Jakub January 2022 (has links)
The diploma thesis deals with the development of a new material for the establishment of a layer of the ground body of a railway undercarriage purely on the basis of secondary raw materials. The theoretical part presents the characteristics of structural layers, materials used for bonded substrates, including their requirements. The following are the general conditions for the creation of base layers from purely secondary raw materials and previous experience with the issue. The introduction of the experimental part of the thesis sets out the basic parameters of secondary raw materials (construction recyclates, waste from railway bed cleaning, dust from cement plant) and energy by-products (fly ash, coal slag and municipal waste incinerator), which together form the raw material base. Grain size, absorbency, moisture, bulk density, chemical analysis and pollutant content were determined on the raw materials. Bulk densities and compressive strengths of the bonded mixtures were determined. The optimum humidity of all mixtures was determined by the Proctor standard test. Experimental verification was performed on testing of bonded mixtures in order to verify the effect of cement dose, when the original dose of 8% was optimized for construction recycled and slag from municipal waste incinerator to 4%, due to high strengths ranging from 4.5 to 6.0 MPa. Further optimization also included the addition of an energy by-product in a proportion of 10% of the weight of the secondary raw material. At the end of the experimental part, two optimal recipes were selected (recycled concrete with 4% cement and 10% fluid fly ash; slag from a municipal waste incinerator with 3% cement and 10% fluid fly ash), which underwent advanced testing in the form of frost resistance and resistance to water and a functional sample was designed. The final functional sample is recycled concrete with cement and 10% addition of fluid fly ash, which is suitable for core layers without frost loading.
20

Elektricky vodivé kompozity na bázi druhotných surovin / Electrically conductive composites based on secondary raw materials

Baránek, Šimon January 2021 (has links)
Electroconductive composites are modern materials that are commonly used in many industries such as the construction industry among others. For example these materials can be useful as sensors for monitoring changes in constructions. The aim of this thesis is the research of electrically conductive silicate composite based on secondary raw materials. The design of this composite is based on the development of its own mixtures and experimental verification of the effect of the structure. The introduction part consists of a detailed analysis of 15 materials. Samples of the 5 fine and 2 coarse electrically conductive fillers were tested. Composite with filler Condufit C4 was selected as representative for type of fine fillers. Composite with filler Supragraphite C300 was selected as representative for type of coarse fillers. The selection of the composites was based on the impedance of the fabricated composites with these fillers. Subsequently, the individual components of the primary mixture were substituted. The cement was replaced by high-temperature fly ash in the amount of 20, 30, and 40 %, the aggregate of a similar fraction was replaced by steel sawdust, and the primary electrically conductive fillers were replaced by secondary ones in the amount of 30 and 50 %. All proposed replacements reduced the impedance of the composite. The most effective replacement for impedance reduction was replacement with waste graphite (up to 92 % reduction), which also slightly improved the mechanical properties of the composite. The result of this thesis is an optimized electrically conductive composite based on secondary raw materials with a fine type of filler with 30 % replacement by waste graphite "odpad vysavač"which achieves an impedance of 5 ohms. The partial goal of this thesis is a verification of the influence of moisture on the impedance of composites. Results are significantly affected by moisture when using the coarse type of filler, when using the fine type are not.

Page generated in 0.0747 seconds