This thesis deals with problems of electrical insulation materials based on epoxy composites used in the electronics industry. This thesis is divided into theoretical part focused on composite materials, their technological processing and diagnostics. It also describes dielectric materials, their properties and events taking place in their structure. The experimental section describes the measurement of electrical properties of samples of electrical insulating materials with different types of fillers.

Graphen, eine zweidimensionale Kohlenstoffstruktur, ist ein junger Füllstoff im Nanometerbereich und besitzt ausgezeichnete physikalische Eigenschaften. Da typische Füllstoffe im Mikrometerbereich, wie z. B. Glasfasern oder Ruße, an ihre Grenzen stoßen, werden zunehmend Nanofüllstoffe in polymeren Kompositen eingesetzt. Grund dafür ist ihre große spezifische Oberfläche und die daraus resultierenden Polymer-Füllstoff-Wechselwirkungen. Das große Potential von graphenbasierten Kompositen wurde bereits in vielen Studien nachgewiesen. Diese erfolgten jedoch vielmals im Labormaßstab und es existieren keine bekannten skalierbaren Prozesse zur Herstellung und Weiterverarbeitung dieser Materialien. Aus diesem Grund wurde in dieser Studie die gesamte Prozesskette von der Materialherstellung über die Verarbeitung bis zum Endprodukt im industriellen Maßstab berücksichtigt. Die Untersuchungen zeigen, dass die handelsüblichen Graphen-Typen keinem idealen Graphen entsprechen, da sie eine mehrschichtige und somit graphitartige Struktur aufweisen. Aufgrund der geringen Bindungskräfte zwischen den einzelnen Graphenschichten bilden die Agglomerate des Graphens eher eine Schwachstelle im Bauteil, so dass keine überproportionale Erhöhung der mechanischen Eigenschaften zu beobachten ist. Die elektrischen und thermischen Eigenschaften der graphenbasierten Verbindungen bleiben weit unter den Erwartungen. Das Forschungsprojekt zeigt die Möglichkeiten und Grenzen von graphenbasierten Kompositen. Derzeit ist mit den aktuell verfügbaren kommerziellen Graphen-Typen eine signifikante Verbesserung der Eigenschaften nicht zu erreichen. Daher ist die Übertragung der Ergebnisse aus Experimenten im Labormaßstab hin zu industriellen Anwendungen derzeit nicht möglich.

Tillverkning av portlandklinker står för ungefär fem procent av världens totala koldioxidutsläpp. Det finns därför ett allmänt intresse att minska användandet av portlandklinker. Klinkern kan antingen ersättas av andra cementerande material, eller så kan nya cementsnåla recept utformas. I den här rapporten har två cement med inmald flygaska respektive slagg från Cementa AB undersökts. För att undersöka klinkerersättnings-materialens potential har tester för tryckhållfasthet, uttorkningskrympning, bindetid, värmeutveckling och arbetbarhet utförts. Resultaten visar att skillnaderna mellan försökscementen och byggcementet är så pass små att båda bör kunna användas som byggcement. Ytterligare har ultrafiller av kalksten använts som ersättare för att minska cementhalten i betongen. Det går lika bra att delvis ersätta försökscementen med ultrafiller som det gör för byggcementet. Med cementsnåla recept och större del ersättningsmaterial finns det stora möjligheter att spara på energi och miljö. Detta borde i framtiden kunna leda till ett bättre och mer miljövänligt byggmaterial. / Manufacture of clinker is responsible for about five percent of the total global carbon dioxide emissions. Therefore, there is a general interest in reducing the use of clinker. Clinker can either be replaced by other cementitious materials, or reduced by using lean-cement recipes. This report examines two experimental cements, one with fly ash and one with slag, developed by Cementa AB. To examine the potential of clinker replacement materials, tests for compressive strength, drying shrinkage, initial setting, heat generation and workability, were performed. The results show that the differences between the experimental cements and the reference are so small that both are useable as building cements. In addition, an ultrafine filler of limestone is used as a replacement material for further reduction of the clinker content in concrete. It was also found, that it is just as efficient to partly replace the experimental cements with ultrafine filler as in the reference cement. There are great opportunities to save energy and the environment impact with both clinker-saving cement recipes and with cement replacement materials. This should lead to a better, more environmentally friendly, building material in the future.

Global warming sets a high demand to reduce the CO2 emissions of vehicles. In the European Union heavy-duty road transports account for 6 % of the total greenhouse gases and one of the main factors affecting these emissions is related to the rolling resistance of tyres. The optimal usage of tyres is an important part of solving these challenges, thereby it is important to understand the parameters affecting rolling resistance and the different compromises coupled to them. These compromises could be analysed using computational and experimental methods. To set out the groundwork necessary to minimise the energy consumption of trucks and assess the different parameters affecting tyre behaviour, the following studies have been conducted during this thesis. A framework to model and parametrise truck tyre rubber has been developed for finite element simulations. The presented parallel rheological material model utilises Mooney-Rivlin hyperelasticity, Prony series viscoelasticity, and perfectly plastic networks. A method to reduce tuneable parameters of the model, which significantly simplifies possible parameter studies, is presented. The model has been parametrised using test data from dynamic mechanical analysis of samples from a long haulage heavy truck tyre, and shows a good agreement with the test data. To test the suitability of the modelling technique for tyre simulations, the constitutive model is used in various tyre simulations using the arbitrary Lagrangian-Eulerian method. The material modelling technique is shown to work for static force-deflection as well as dynamic simulations estimating longitudinal force build-up with varying slip levels. Additionally, the modelling technique captures the uneven contact pressure in steady-state rolling, which indicates that the model could also be used in rolling resistance simulations. To study the change of ambient temperature on rolling resistance using experimental methods, a climate wind tunnel is used where the rolling resistance is quantified using a measurement drum. Tests were conducted between -30 °C and +25 °C, and a considerable ambient temperature dependency on rolling resistance was found. Moreover, temperature measurement inside a tyre shoulder is a good indicator for rolling resistance in a broad range of ambient temperatures. Finally, battery-electric long haulage truck driving range calculations are also conducted with varying rolling resistance and air density at different temperatures, showing a significant decrease of driving range with decreasing ambient temperature. / Den globala uppvärmningen ställer höga krav på att minska tunga fordons CO2-utsläpp. Tunga transporter står för 6 % av de totala växthusgaserna i Europeiska unionen och att fokusera på optimal användning av däck är en viktig del för att minska förorenande växthusgaser. Därför är det viktigt att förstå parametrar som påverkar rullmotståndet och olika kompromisser kopplade till dem. Dessa kompromisser skulle kunna analyseras med hjälp av beräkningsmetoder och experimentella metoder. För att lägga grunden för att minimera energiförbrukningen för lastbilar och bedöma olika parametrar som påverkar däckens beteende, har följande studier genomförts i denna avhandling. Ett ramverk för att modellera och parametrisera lastbilsdäcksgummi utvecklades för finita elementmetod-simuleringar. Den presenterade parallella reologiska materialmodellen använder Mooney-Rivlin hyperelasticitet, Prony-series viskoelasticitet och perfekt plastiska nätverk. En metod har utvecklats för att reducera antalet justerbara materialparametrar i modellen, vilket avsevärt förenklar möjliga parameterstudier. Modellen har parametriserats med hjälp av testdata från dynamisk mekanisk analys och visar en god överensstämmelse mellan testdata och simuleringar. Provstavarna skars ut från ett lastbilsdäck för tunga fordon. För att testa modelleringsteknikens lämplighet användes den konstitutiva modellen i olika däcksimuleringar. Materialmodelleringstekniken har visat sig fungera för statisk vertikalstyvhet såväl som dynamiska simuleringar som uppskattar longitudinell kraftgenerering med varierande slipnivåer och olika friktionskoefficienter. Modelleringstekniken fångar ojämnt kontakttryck vid stationär rullning, vilket indikerar att modellen även kan användas i simuleringar av rullmotstånd. För att studera omgivningstemperaturens inverkan på rullmotståndet med experimentella metoder användes en klimatvindtunnel. Tester utfördes mellan -30 °C och +25 °C och rullmotståndet bestämdes med en mättrumma. Ett avsevärt beroende av omgivningstemperaturen på rullmotståndet påvisades. Dessutom indikerade provningen att temperaturmätning inuti däckskuldran är en bra indikator för rullmotstånd i ett brett område av omgivningstemperaturer. Räckviddsberäkningar för en elektrisk fjärrtransportlastbil utfördes med varierande rullmotstånd och luftdensitet vid olika temperaturer, vilket visade en signifikant minskning av körräckvidden med sjunkande omgivningstemperatur. / <p>QC 220525</p>

Självkompakterande betong (SKB) eller som den också kallas vibreringsfri betong upptäcktes och utvecklades i Japan i slutet av 1980- talet. Anledningen till detta utvecklingsarbete var att betong gjutning väldigt kämpigt och tillgången på erfarna betongarbetare började bli låg. I Sverige använde man självkompakterande betong året 1993 som tekniken hämtades hem av CBI Betonginstitutet. Användning av självkompakterande betong leder till många fördelar som skiljer sig från den vanliga betongen avseende arbetsmiljö t.ex. slipper man vibrering och undviker tungt arbete som i konsekvens minskar antal skador på arbetsplatsen. Utöver detta ger SKB förkortad arbetstid, bättre utförande och möjlighet till arbetskraftbesparing. Sedan 1997 har Sverige ökat användning av SKB i platsgjutning medan andra länder som Danmark har gått fram till ca 30 % av sin platsgjutning. Den låga användningen beror på att självkompakterande betong är väldigt känslig och dyrare eftersom den innehåller mer tillsatsmaterial. Huvuddelen av projektet bestod av att ställa frågor till experter i byggbranschen om självkompakterande betong för att få största möjliga mängd av informationer. Informationer som vi har fått var emellan åtta besök och sex mail. Syftet med examensarbete är att öka kunskap om orsaken till låg utveckling av SKB på platsgjutning och kunskap om arbetsmiljö. Vidare syftar arbetet till att lyfta fram de arbetsmiljömässiga och konstruktiva fördelarna samt sprida information om dessa. Informationerna visar att anledningen till den låga användningen av SKB framför allt är priset.  Men tidigare misslyckanden och varierande betongegenskaper är också en av anledningarna. Genom att öka användning av SKB där man många fördelar bland annat ekonomisk vinst på lång sikt och framför allt bättre arbetsmiljö med tanke på samhället. / Self-compacting concrete (SCC) or vibrated concrete was invented and developed in Japan in the late 1980's. Working with concrete is very hard and all of that is because of injuries that come from using of the usual concrete.  In Sweden, they used self-compacting concrete since 1993 when the technology has brought to Sweden from Japan by the Swedish cement and concrete Research institute. Self-compacting concrete has many advantages that are different from the traditional concrete according to the work environment which include avoidance of vibration and heavy work and all these can reduce the number of injuries at workplace. Shortened construction time and possibilities to save manpower are additional benefits. Today, self-compacting concrete is used for about 10 % on site casting in Sweden. Many other countries have gone forward in using of SCC, Denmark uses about 30%. The low use is due to the sensitivity of SCC and expensive because it contains more filler. The main work of the project consists of the interviews with the related persons in the building branch and questions to them about self-compacting concrete to get the maximum amount of information. Information that we have received was between eight visits and six mail. The aim of the thesis is to increase knowledge about the cause of the low development of SCC in place casting and knowledge of the work environment. Furthermore, this work aims to highlight the work environment and constructive advantages and disseminate information about them. The study shows that the reason for the low use of SCC is especially the price. But the previous failures and varying concrete properties are also such of these reasons. Increasing the use of SCC leads to many benefits including economic profit in the long term, and especially from the society side.

Role of silane-treated stöber silica as reinforcing filler for nitrile rubber (NBR) has been studied. Stöber silica is synthesized by sol–gel method, and the surface of silica is modified with the treatment of silane-coupling agent viz. γ-mercaptopropyltrimethoxysilane (γ-MPS) in varying proportions. Average particle size of stöber silica of spherical shape in the range of 200 to 400 nm is evident from scanning electron microscopy (SEM). Surface modification of silica particle with silane-coupling agents decreases surface energy and reduces agglomeration of silica particles in rubber matrix. Stress–strain study and dynamic mechanical analysis of silica-filled composites are compared with the unfilled ones. Analysis of cross-linking density, mechanical properties, and storage moduli indicates a strong rubber–filler interaction in the silane-treated, silica-filled NBR composites. Silane treatment is found to be effective in uniform dispersion of silica in rubber matrix and in improving the mechanical properties of rubber composite. Different functionalities of organosilane at its both end improve the compatibility of silica with rubber matrix and offer better rubber–filler interaction.

This work, conceived as a second step in the development of high-performance damping materials suitable for seismic application, describes the preparation and characterization of complex natural rubber-based composites containing hybrid nano- and conventional fillers. The cluster–cluster aggregation model was used to assess the apparent filler networking energy. The values obtained suggested that the presence of the hybrid nanofiller strengthens the filler networking. The same model was used to understand the mechanisms of energy dissipation. The damping coefficient was found to be in the sought range between 10% and 20% (at 0.5 Hz and high shear strain).

Indiana University-Purdue University Indianapolis (IUPUI) / In adhesive dentistry, obtaining a good bond is a fundamental goal. It has been suggested that filler addition to the adhesives would increase the bonding strength of the adhesive layer. Halloysite aluminosilicate nanotubes (HNTs) are biocompatible, hydrophilic, durable, and have high mechanical strength. These advantages make them good candidates to be used as reinforcing agents for improving the properties of dental adhesives. The objective of this study was to evaluate the effect of incorporating HNTs into a commercial two-step etch-and-rinse adhesive system or one-step self-etch adhesive system on dentin shear bond strength. HNTs were incorporated into the two commercial adhesive systems in 0 wt%, 5 wt%, 10 wt%, and 20 wt%. The commercial control adhesives and the experimental adhesives were used to bond occlusal dentin of 120 extracted human molar teeth and then tested for shear bond strength by a universal testing machine with a semi-circular edge at a crosshead speed of 1.0 mm/min. Debonded specimens were examined under light microscopy to evaluate the fracture pattern. Resin-dentin interface were evaluated under scanning electron microscopy (SEM) after bonding dentin slabs using commercial control adhesives and experimental adhesive that showed numerically highest shear bond strength from each adhesive system. Two-way ANOVA was used to evaluate the effects of adhesive system and nanofiller content on shear bond strength. Pair-wise comparisons between groups were made using Fisher's (LSD) (p < 0.05). For the self-etch adhesive system, only incorporation of 5 wt% showed a significant increase in shear bond strength to dentin compared with the commercial control group. For the etch-and-rinse adhesive system, there was no significant difference in shear bond strength between HNTs filled adhesives groups and the commercial control group. Resin-dentin interface SEM evaluation showed nanotubes infiltrated into dentinal tubules. In conclusion, incorporating the self-etch adhesive system with 5 wt% HNTs increased the bond strength to dentin. Incorporation of up to 10 wt% filler concentration into both the self-etch and the etch-and-rinse adhesive systems did not adversely affect the bond strength to dentin or the handling properties. HNTs can penetrate along with resin tags into dentinal tubules, which could expand the use of their unique properties.

The master's thesis deals with the project of the new building of the Sports Hall in the Staré Město at the stage of project documentation for the construction on plots 2420/1, 2420/41, 2420/42, 2420/43, 2420/44, 4568/38, 6277/2, 6277/3 , 2517/4. The plots on which the construction is proposed are flat or slightly sloping. The building has no basement, has two floors. The perimeter structures in the locker rooms are designed from ceramic blocks of the POROTHERM system, including the thermal insulation system according to the principles of ETICS, and in the gym from the curtain walling of the KINGSPAN system. Horizontal structures are folded prestressed ceiling panels SPIROLL. The cloakroom building is covered by a warm flat roof, and the gymnasium by barrel roof made of glued laminated girder. In the sports hall, 5 changing rooms are designed, including sanitary facilities, then facilities for the operation of the hall and refreshments for spectators.

Electroconductive silicate-based composites are advanced materials that allow building structures to perform several different functions simultaneously. Addressing the issues of their development and use is a suitable topic for research work. The aim of this work is to study the effect of structure on the resistivity of silicate composite. The structure of electrically conductive composites is studied on dry cement paste and mortar mixtures as well as on test bodies made of hardened cement paste and mortar after 28 days of curing. Based on the analysis of the raw materials, six suitable electroconductive fillers are selected based on particle size, resistivity, and water absorption. The parameters of dry cement paste and hardened cement paste with replacement of 4-19 wt. % cement by the selected fillers are determined. Two of the fillers are selected for use in dry and hardened mortar. Resistivity is determined for all dry mixes and hardened composites variants, and percolation thresholds are approximately determined. By studying the structure of the selected variants, it is shown that the most important parameters that have the greatest influence on the resistivity of the silicate composites are mainly the particle size and the intrinsic resistivity of the electrically conductive filler. For silicate composites in the hardened state, the volume of hydration products, especially portlandite and C-S-H gels, also has a significant influence. For both dry blends and hardened composites, it was found that the smaller the particle size of the electroconductive filler, the smaller the representation needed to reach the percolation threshold. Portlandite and C-S-H gels in the volume of the hardened composite cause its high resistivity. The resistivity of the hardened composite is always higher than that of the dry blends. Thus, the proportion of electroconductive filler needed to reach the percolation threshold is higher in hardened composites than in dry mixes. The resist