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Estudo das alternativas de uso da fibra de vidro sem características álcali resistente em elementos construtivos de cimento Portland / Study of alternatives to use de glass fibers without alkali-resistant characteristics in the cement composite products for civil constructionPeruzzi, Antônio de Paulo 13 December 2007 (has links)
As fibras de vidro são usadas há alguns anos com a finalidade de melhorar a resistência à tração e ao impacto de compósitos cimentícios. Mas, os álcalis do cimento Portland atacam essas fibras causando a degradação de suas propriedades mecânicas. Para contornar essa degradação, há alguns anos, foram desenvolvidas as fibras álcalis-resistente (AR) que, embora tenham apresentado melhor desempenho que as fibras de vidro convencionais, ainda apresentam perda de desempenho com o tempo. Esse trabalho trata do desenvolvimento de um novo tipo de fibra na forma de telas, a partir das fibras de vidro convencionais, usando uma impregnação de PVC como barreira para impedir o ataque químico dos álcalis do cimento. A análise da eficiência dessas telas em relação à durabilidade foi feita por meio de processo de envelhecimento acelerado e, a seguir, foram estudados os vários tipos de aplicação delas em elementos construtivos à base de matrizes cimentícias concomitantemente como o uso de barras de GFRP. Como resultado final comprovou-se a eficiência da resina desenvolvida na pesquisa para impregnação das fibras em relação à sua durabilidade frente ao meio alcalino do cimento Portland e a adequação do uso das telas impregnadas com essa resina em diversos tipos de produtos de matrizes cimentícias para construção civil. / Glass fibers are used since several years to improve the tensile and impact strengths of cement composites. But, the alkalis from Portland cement attack the glass fibers causing the deterioration of its mechanical properties. For overcome this degradation, some years ago, were developed the fibers alkali-resistant (AR) which, although presented as the best performance fiber glass conventional, still show a loss of performance over time. This work deals with the development of a new type of fiber in the form of mesh, from conventional glass staple fibers, using a PVC impregnation as barrier to hinder the chemical attack alkalis them it cement to these. The analysis of the efficiency of these fibers in relation to the durability was made by means of process accelerated ageing and, next, concomitantly studied some types of application of these fibers in constructive elements to the cements matrix with the use of bars of GFRP. The final result showed tha the resin developed in this work is efficient how coating of conventional fibers to get durability on the alkaline environment and the mesh impregnated with this resin are appropriates of the use in many kinds of products to construction made from cements matrixes.
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Applicatiation of Electrical Fiberglass Filter Coated with Nano-sized TiO2 Photocatalyst on Photoelectrocatalytic Degradation of AcetoneLi, Wan-Hua 06 September 2010 (has links)
The study combined photoelectrocatalytic technology (PEC) with electrical glassfiber filter (EGF) to decompose volatile organic compounds (VOCs). External electrical voltage was applied to retard the
recombination of electron-electron hole pairs and increase the surface temperature of the photocatalysts coated on the electrical glassfiber filter,
which could further decompose VOCs more effectively via photoelectrocatalytic technology. Acetone was selected as the gasous pollutant for this particular study. A commercial TiO2 photocatalyst
(AG-160) was coated on GFF via impregnation to decompose acetone in a batch PEC reactor. Operation parameters investigated in this study
included acetone concentration (50~400 ppm), electrical voltage (0~6,500V), water content (0~20,000 ppm), reaction temperature (40¢J~80¢J).The incident UV light of 365 nm wavelength was irradiated by three
15-wat low pressure mercury lamps (£f=365 nm) placing above the batch PEC reactor. The TiO2-coated EGF was placed at the center of the batch PEC reactor. Acetone was injected into the reactor by a gasket syringe to conduct the PEC decomposition test. Acetone was analyzed quantitatively by a gas chromatography with a flame ionization detector
(GC/FID). Finally, a Langmuir-Hinshelwood kinetic (L-H) model was proposed to simulate the PEC reaction rate of acetone.
Experimental results showed that the size range of the self-produced nano-sized photocatalyst prepared by sol-gel was 35~50 nm. Three duplicate tests of PC and PEC degradation of acetone indicated
that TiO2 was not deactivated during the PC and PCE reactions, hence TiO2 can be reused in the experiments. Results obtained from the PC and PEC degradation experiments indicated that the PEC reaction rate was higher than the PC reaction rate.The PEC reaction rate increased with applied electrical voltage, and the highest decomposition efficiency
occurred at 6,500 V. Electrical field generated by the differences of electrical voltage can effectively enhance the oxidation capability of TiO2 since electron (e-) can be conducted to retard the recombination of electron and electron hole pairs. Both PC and PEC technologies could be used to decompose acetone. Among them, PEC had highter
decomposition efficiency of acetone than PC up to 34%. Rsults obtained from the operation parameter tests reaveled that raising electrical voltage could enhance the decomposition efficiency of acetone only for electrical voltages above 2,000 V. However, the decomposition efficiency of acetone tended to level off as electrical voltage became higher.
Zero-order reaction rate of the PEC reaction was observed for initial acetone concentration of 100~400 ppm, while the PEC reaction decreased gradually for initial acetone concentration reaction below 100 ppm. It revealed that the PEC reaction was pseudo ozero-order for initial acetone concentration of 100~400 ppm, and pseudo first-order reaction for acetone concentration below 100 ppm. Additionally, the PC reaction rate increased with temperature at 45-80¢J. However the PEC reaction rate increased with temperature at 45-60¢J, and decreased with temperature at 60-80¢J. An adsorptive competition between acetone and water molecules at the active sites over TiO2 surface caused either promotion or
inhibition of TiO2 decomposition depending on moisture content . For the PC and PEC reactions, the optimum operating condition of water vapor
concentration was 10,000 ppm, but inhibition occurred when the water vapor concentration increased up to 20,000 ppm.
Finally, the Langmuir-Hinshelwood kinetic model was applied to investiage the influences of reaction temperature, initial concentration of acetone, and water content on the photoelectrocatalytic reaction rate of acetone. Model simulation results showed that photoelectrocatalytic reaction rate constant of acetone(kLH) and adsorptive equilibrium constant(KA) increased with electrical voltage and acetone initial concentration. This study sevealed that experimental and simulated results were in good agreement. Thus, PEC reaction rate of acetone on the surface of TiO2 can be also succesfully simulated by the L-H kinetic model.
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Estudo das alternativas de uso da fibra de vidro sem características álcali resistente em elementos construtivos de cimento Portland / Study of alternatives to use de glass fibers without alkali-resistant characteristics in the cement composite products for civil constructionAntônio de Paulo Peruzzi 13 December 2007 (has links)
As fibras de vidro são usadas há alguns anos com a finalidade de melhorar a resistência à tração e ao impacto de compósitos cimentícios. Mas, os álcalis do cimento Portland atacam essas fibras causando a degradação de suas propriedades mecânicas. Para contornar essa degradação, há alguns anos, foram desenvolvidas as fibras álcalis-resistente (AR) que, embora tenham apresentado melhor desempenho que as fibras de vidro convencionais, ainda apresentam perda de desempenho com o tempo. Esse trabalho trata do desenvolvimento de um novo tipo de fibra na forma de telas, a partir das fibras de vidro convencionais, usando uma impregnação de PVC como barreira para impedir o ataque químico dos álcalis do cimento. A análise da eficiência dessas telas em relação à durabilidade foi feita por meio de processo de envelhecimento acelerado e, a seguir, foram estudados os vários tipos de aplicação delas em elementos construtivos à base de matrizes cimentícias concomitantemente como o uso de barras de GFRP. Como resultado final comprovou-se a eficiência da resina desenvolvida na pesquisa para impregnação das fibras em relação à sua durabilidade frente ao meio alcalino do cimento Portland e a adequação do uso das telas impregnadas com essa resina em diversos tipos de produtos de matrizes cimentícias para construção civil. / Glass fibers are used since several years to improve the tensile and impact strengths of cement composites. But, the alkalis from Portland cement attack the glass fibers causing the deterioration of its mechanical properties. For overcome this degradation, some years ago, were developed the fibers alkali-resistant (AR) which, although presented as the best performance fiber glass conventional, still show a loss of performance over time. This work deals with the development of a new type of fiber in the form of mesh, from conventional glass staple fibers, using a PVC impregnation as barrier to hinder the chemical attack alkalis them it cement to these. The analysis of the efficiency of these fibers in relation to the durability was made by means of process accelerated ageing and, next, concomitantly studied some types of application of these fibers in constructive elements to the cements matrix with the use of bars of GFRP. The final result showed tha the resin developed in this work is efficient how coating of conventional fibers to get durability on the alkaline environment and the mesh impregnated with this resin are appropriates of the use in many kinds of products to construction made from cements matrixes.
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Undersökning av riktigheten för värmekonduktiviteter i ett vattenrutschbaneelement / Investigation of the propriety thermal conductivity for a water slide elementOlsson, Erik, Högberg, Fanny January 2022 (has links)
Den här studien handlar om att undersöka värmemotståndet för ett vattenrutschbaneelement för att se om det finns en skillnad mellan schablonmässiga och uppmätta värden för värmekonduktiviteten hos materialen men även undersöka hur stor påverkan de längsgåendeflänsarna har på transmissionsförlusten. Det finns ofta en skillnad mellan det schablonmässiga och faktiska värden när matningar genomförs på färdigställda konstruktioner. Syftet med studien är att undersöka riktigheten av schablonmässigt bestämt värmemotståndet för ett vattenrutschbaneelement (banmodell typ-1000) som produceras av Hydro Sport AB. Studien kommer även att undersöka materialens temperaturberoende utifrån värmekonduktivitet. En laboratoriemätning utfördes i ett klimatkammarskåp med värmeflödesmätare och termoelement för att bestämma värmekonduktiviteten för glasfiberlaminatet (GFRP) och mäta värmemotståndet för den sammansatta konstruktionen och genom att subtrahera glasfiberlaminatet värmemotstånd för att erhålla värmekonduktiviteten för Armaflex isoleringen. De framtagna värmekonduktiviteterna användes som parametrar i Comsol Multiphysics simuleringarna för att undersöka hur stor skillnad schablonmässiga och uppmätta värden har för denna specifika vattenrutschbana. Handberäkningar gjordes för att säkerställa att Comsol Multiphysics simuleringarna var pålitliga. Resultaten som framtagits i studien visar på att båda materialen men framför allt glasfiberlaminatet hade ett lägre värmekonduktivitetsvärde än det schablonmässiga som används i beräkningar i dagsläget. / This study is about examining the thermal resistance of a water slide element to see if it’s a difference between standard values and measured values for the materials thermal conductivity and also see how big an impact the horizontal flanges have for the heat balance of the structure. There is often a difference between the theoretical and actual values that is measured when the construction is finished.The purpose of this study is to validate the accuracy of the thermal resistance of a water slide element (track model typ-1000) that is produced by Hydro Sport AB. This study also covers thermal conductivity temperature dependent for the materials. A laboratory measurement was performed in a climate chamber with heat flux meters and thermocouples to obtain the thermal conductivity for the glass fibre reinforced polymer (GFRP) and measure the heat resistance for the whole composite construction and from there substract the GFRP heat resistance to obtain the thermal conductivity for the Armaflex insulation. The obtained thermal conductivity was used as parameters for the simulations in Comsol Multiphysics to investigate how big the impacts are between standard values and measured for this particular water slide type. To make sure that the Comsol Multiphysics simulations were trustworthy a hand calculation was made for this purpose.The results in this study revealed that both materials but especially GFRP had a better thermal conductivity than the standard value that is used today.
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Effects of Temperature and Moisture Content on Young’s Modulus in Glass Fiber Reinforced PolyamideSandberg, Joel, Sjölin, Samuel January 2022 (has links)
This thesis was made in cooperation with Roxtec. Roxtec specialises in cable sealingsolutions and are world leading in their area. In many of Roxtec’s products steel isused in the frame holding the sealing rubber. To lower Roxtec’s environmental foot-print plastic would be used instead in the frames if possible, more specific polyamide6.6 with 25% glass fiber reinforcement (PA66GF25). Polyamide is affected to agreater extent by temperature and humidity than steel and therefore poses a greaterrisk when considering the sealing capability in harsh conditions. The purpose of thisthesis is therefore to investigate the effects on the Young’s modulus by temperatureand relative humidity, which both correlate to moisture content in the plastic. Theintended temperature and moisture saturation interval are -40◦C to 80◦C and 0% to100% moisture saturation respectively. Tensile test samples were made through machining samples from existing productsand conditioning them to desired moisture content. With the use of tensile testingthe Young’s modulus could be determined for a number of combinations of temper-ature and moisture content. From this data an approximated polynomial surfaceof the Young’s modulus could be produced. The conditioning of the test piecescould be accelerated by submersion in heated water, decreasing conditioning timeto less than two days. The approximation of the Young’s modulus function couldbe done using polynomial approximation. The resulting polynomial for the positivetemperatures was of the third order dependant of the two variables moisture con-tent and temperature. For the negative temperatures a single variable polynomialwas approximated due to only one moisture content being tested for. To ensure thevalidity of the model each test combination consisted of three individual tensile testof which an average was calculated. The approximated function was then comparedto a data sheet value for a certain moisture content and temperature. From theresulting surface approximation of the Young’s modulus in positive temperatures itcan be deduced that PA66GF25 is more greatly affected by moisture content thantemperature. Especially at low levels of moisture content where the rise in Young’smodulus is exponential while more linear at higher moisture contents. The maximumand minimum Young’s modulus was found to be 8 GPa and 2.7 GPa respectively.The negative temperature approximation was restricted to one moisture content andtherefore resulted in a graph. The behaviour of this graph was likely a result of icein the material as similarities to a study regarding the mechanical properties of icewas found. / Detta examensarbete gjordes i sammarbete med Roxtec. Roxtec specialialiserar sig ikabeltätningslösningar och är världsledande i området. I många av Roxtecs produk-ter så används stål till att försegla gummi. För att minska Roxtecs miljöpåverkan såskulle plast användas till tätningarnas ramar om möjligt, speficikt polyamid 6.6 med25% glasfiberförstärkning (PA66GF25). Polyamid påverkas till större andel av tem-peratur och luftfuktighet än stål och utsätts därmed för en större risk med avseendepå tätnings kapabiliteten i tuffa miljöer. Syftet med detta arbete är därmed attundersöka effekterna på Elasticitetsmodul från temperatur och luftfuktighet, vilkakorrelerar mot fuktmättnadsgraden i plasten. Det avsedda temperaturintervallet är-40◦C till 80◦C och 0% till 100% fuktmättnadsgrad. Dragprovstesterna gjordes genom bearbetning av existerande produkter följt av kon-ditionering till önskad fuktmättnadsgrad. Genom genomförandet av dragprov, såkunde Youngs modul bestämmas för ett antal kombinationer av temperaturer ochfukterhalter. Från denna data så kunde en polynomyta för Youngs modul approx-imeras. Konditioneringen av dragprovsbitarna kunde accelereras genom nedsänkningi upphettat vatten, vilket minskade konditioneringstiden till mindre än två dygn. Ap-proximeringen av funktionen för Youngs modul kunde göras genom polynomapprox-imering, vilket resulterade i en tredje ordnings polynom beroende på två variablernafuktmättnadsgrad och temperatur. En annan approximation gjordes för de nega-tiva temperaturerna, då enbart temperaturberoende beteende undersöktes med enkonstant fuktmättnadsgrad. För att säkerställa validiteten av modellen så gjordestre mätningar på varje testkombination ifrån vilket ett medel kalkylerades. Den ap-proximerade funktionen jämfördes sedan med värdena från datablad för en viss fukt-mättnadsgrad och temperatur. Från den resulterande ytapproximationen av Youngsmodul för de positiva temperaturerna, så kan slutsatsen att PA66GF25 är avsevärtmycket mer påverkad av fukt än temperatur dras. Detta är tydligare för de testernamed låga fuktmättnadsgrader då ökningen av Youngs modul är exponentiell medanden är mer linjär för högre fuktmättnadsgrad. Den maximala och minimala Youngsmodul visade sig vara 8 GPa och 2.7 GPa respektive. De negativa temperaturernasapproximation var begränsad till en fuktmättnadsgrad och därmed resulterade i engraf kring 5 GPa. Beteendet hos denna graf var troligtvis ett resultat från isen imaterialet vars beteende är snarlikt en studie på isens mekaniska egenskaper visadepå.
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