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  • 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.
1

Comportamento das forças de adesão do adesivo selante de silicone e do mastic butílico sob o efeito da radiação ionizante. / Behavior of the adhesion forces of silicone adhesive sealant and butyl mastic after the exposure to ionizing radiation.

Costa, Wanderley da 15 December 2011 (has links)
Os adesivos são produtos capazes de manter materiais unidos, mediante ligações entre as superfícies. Selantes são produtos capazes de manter preenchido um espaço entre duas superfícies, por meio de uma barreira que se configura como uma ponte entre as duas superfícies. O mastic é um produto obtido por uma mistura de substâncias tendo como principal polímero o butil, com consistência de uma massa não secativa que pode ser utilizada como selante. Os polisiloxanos, também conhecidos como silicones são os mais importantes polímeros sintéticos com estrutura inorgânica, e são matrizes dos adesivos selantes de silicone. Para comprovar como o comportamento das forças de adesão destes produtos acontece, foram utilizadas cinco técnicas diferenciadas. Estes produtos foram submetidos a duas condições distintas para verificar o comportamento da adesão, um em condições ambiente e outro sob influência de radiação ionizante. Os resultados obtidos demonstraram não só a diferença entre produtos (silicone e mastic), mas também que as forças de adesão têm comportamentos diferentes nas condições às quais foram submetidas às amostras. Com isto atingi-se o objetivo desse estudo que é apresentar a diferenciação entre o mastic e o silicone, muitas vezes considerados como um só produto denominado mastic. Desta forma comprova-se que: 1. o silicone pode ser considerado um adesivo selante em condições ambientes, 2. o mastic melhora consideravelmente sua adesão, quando submetido à radiação ionizante, e esta característica de adesão pode ser uma excelente alternativa para o mercado de adesivos. / Adhesives are products that can keep materials together by bonds between the surfaces. Sealants are products that can keep filled a space between two surfaces, through a barrier that is configured as a \"bridge\" between the two surfaces. The mastic is a product made of a mixture of substances with the primary butyl polymer, with the consistency of a mass not dried that can be used as a sealant. The polysiloxane, also known as silicone are the most important synthetic polymers with inorganic structure, and are matrices of silicone adhesive sealants. To demonstrate the behavior of the adhesive forces of these products under different conditions, we used five different techniques. These products were subjected to two different conditions to verify the behavior of adhesion, one at the environmental condition and another under the ionizing radiation. The results showed not only differences between products (silicone and mastic), but also that the adhesive forces have different behaviors under the conditions which the samples were subjected. With this was reached the goal of this study that aspired show the differences between the mastic and silicone, this last one is often considered - erroneously - the same as mastic. Thus it was proven that: 1. silicone can be regarded as an adhesive and a sealant at ambient conditions, 2. mastic improves substantially adhesion in an environment of ionizing radiation and this property can be an excellent alternative to the adhesive market.
2

Comportamento das forças de adesão do adesivo selante de silicone e do mastic butílico sob o efeito da radiação ionizante. / Behavior of the adhesion forces of silicone adhesive sealant and butyl mastic after the exposure to ionizing radiation.

Wanderley da Costa 15 December 2011 (has links)
Os adesivos são produtos capazes de manter materiais unidos, mediante ligações entre as superfícies. Selantes são produtos capazes de manter preenchido um espaço entre duas superfícies, por meio de uma barreira que se configura como uma ponte entre as duas superfícies. O mastic é um produto obtido por uma mistura de substâncias tendo como principal polímero o butil, com consistência de uma massa não secativa que pode ser utilizada como selante. Os polisiloxanos, também conhecidos como silicones são os mais importantes polímeros sintéticos com estrutura inorgânica, e são matrizes dos adesivos selantes de silicone. Para comprovar como o comportamento das forças de adesão destes produtos acontece, foram utilizadas cinco técnicas diferenciadas. Estes produtos foram submetidos a duas condições distintas para verificar o comportamento da adesão, um em condições ambiente e outro sob influência de radiação ionizante. Os resultados obtidos demonstraram não só a diferença entre produtos (silicone e mastic), mas também que as forças de adesão têm comportamentos diferentes nas condições às quais foram submetidas às amostras. Com isto atingi-se o objetivo desse estudo que é apresentar a diferenciação entre o mastic e o silicone, muitas vezes considerados como um só produto denominado mastic. Desta forma comprova-se que: 1. o silicone pode ser considerado um adesivo selante em condições ambientes, 2. o mastic melhora consideravelmente sua adesão, quando submetido à radiação ionizante, e esta característica de adesão pode ser uma excelente alternativa para o mercado de adesivos. / Adhesives are products that can keep materials together by bonds between the surfaces. Sealants are products that can keep filled a space between two surfaces, through a barrier that is configured as a \"bridge\" between the two surfaces. The mastic is a product made of a mixture of substances with the primary butyl polymer, with the consistency of a mass not dried that can be used as a sealant. The polysiloxane, also known as silicone are the most important synthetic polymers with inorganic structure, and are matrices of silicone adhesive sealants. To demonstrate the behavior of the adhesive forces of these products under different conditions, we used five different techniques. These products were subjected to two different conditions to verify the behavior of adhesion, one at the environmental condition and another under the ionizing radiation. The results showed not only differences between products (silicone and mastic), but also that the adhesive forces have different behaviors under the conditions which the samples were subjected. With this was reached the goal of this study that aspired show the differences between the mastic and silicone, this last one is often considered - erroneously - the same as mastic. Thus it was proven that: 1. silicone can be regarded as an adhesive and a sealant at ambient conditions, 2. mastic improves substantially adhesion in an environment of ionizing radiation and this property can be an excellent alternative to the adhesive market.
3

Glued connection for TCC slabs : Experimental and Numerical investigation

Halilovic, Ervin, Lotinac, Seid January 2022 (has links)
Timber-concrete composite (TCC) structures are becoming more popular in several industrial applications as an efficient method for optimizing the structural performance and the cost of construction as well as lowering the emissions of carbon dioxide. TCC floors are more sustainable than pure concrete floors and more resistant to vibrations and excessive deflections than pure wooden floors. The effectiveness of a TCC floor is dependent on the connection between the materials. The stiffness and strength of the composite element increases by having a rigid connection. An example of a rigid connection is an adhesive-bonded connection, however obtaining a connection without slip is difficult considering there will always be certain amount of slippage in the connection. In this thesis adhesive connections are investigated with two different types of adhesive, one called Sikasil SG-500 and the other Sika PS. The application of the adhesives for the test specimen differ. Since Sika PS is a more fluid glue, a different approach was necessary than for the Sikasil SG-500. Five test specimen were tested of each adhesive by performing double shear push out tests and comparing the results to a numerical model, which was performed in ABAQUS. In the numerical model, the adhesive was created as a cohesive element. Furthermore the properties of the modeled adhesive was based on the experimental results for respective adhesive. The experimental results showed that both adhesives managed the estimated shear force in the serviceability limit state and the ultimate limit state and yet remained in the elastic region. Sikasil SG-500 turned out to be more flexible while Sika PS specimen resulted in higher shear strength. The short creep tests (30 minutes of a constant load) showed that the deformation increased more for Sika PS than for Sikasil SG-500. However both adhesives had large deformations after only 30 minutes. There was also a difference in the average longitudinal shear strength, where it resulted in 1.06 MPa for Sikasil SG-500 and 2.02 MPa for Sika PS. This study indicates that Sika PS is more preferable in TCC structures than Sikasil SG-500.

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