Univ., Diss., 2000--Kassel.

Universiẗat, Diss., 2001--Freiburg (Breisgau).

No description available.

This thesis is concerned with the use of rheological equations of state to describe the behaviour of vulcanised elastomers and, in particular, vulcanised elastomers loaded with carbon black. The properties of these materials are dependent upon the specific combination of elastomer and carbon black, and the effect of carbon black loading is studied by means of experiments on a butadiene-acrylonitrile base polymer KRYNAC 806, unfilled and loaded with 50phr SRF N774 carbon black. The first part of this work concerns small ampIitude oscillatory shear experiments carried out on a Weissenberg rheogoniometer over a range of amplitudes, frequencies, and temperatures. Both materials are found to remain within the linear viscoelastic region for temperatures greater than about -10°c, to obey the time-temperature superposition principle, and to have identical shift factors. Dynamic moduli over a reduced frequency range of about ten decades of log frequency are characterised by the Huet model. The second part concerns finite deformation experiments consisting of prestraining samples in simple tension and applying small axial oscillations when stress relaxation is almost complete. Dependencies of the incremental dynamic moduli measured in this way are investigated with regard to frequency and extension ratio. Moduli measurements indicate that the time dependence of the materials is unaffected by deformation, although relaxation spectrum functions for the filled sample are strain dependent. A criterion is established for testing whether results can be modelled by a certain class of non-linear viscoelastic constitutive equations. A constitutive equation is proposed which represents the strain dependence of moduli for both the filled and unfilled materials. Other published data are shown not to conform to the above criterion. It is also shown that despite this fact, in some cases at least, the proposed constitutive equation provides a better represent at ion of published data than other constitutive equations which have hitherto been applied.

Zugl.: Hamburg-Harburg, Techn. Universiẗat, Diss., 2009.

Univ., Habil.-Schr., 2000--Kassel.

Made available in DSpace on 2014-06-11T19:28:34Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-02-26Bitstream added on 2014-06-13T19:16:36Z : No. of bitstreams: 1 varella_jr_me_guara.pdf: 411771 bytes, checksum: 6018f061abb7c0ab68b42665d02bafa9 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo do trabalho foi determinar parâmetros para avaliar a pinça insersora de ligadura elástica, comparando-a com o aplicador de ligadura elástica. Foi idealizado e construído um dispositivo para medir a força de deslocamento da ligadura elástica, composto por transdutores de força e deslocamento, condicionador de sinais, placa de aquisição de dados e um computador. Para determinar a força de deslocamento foram utilizadas 58 ligaduras elásticas, sendo 29 ligaduras colocadas com o aplicador e 29 inseridas com a pinça. Os resultados mostraram que as ligaduras colocadas com a pinça necessitaram de uma força de deslocamento maior. As medidas da amostra de 45 ligaduras no projetor de perfil mostraram que a pinça esticou menos as ligaduras elásticas durante a manobra de inserção no braquete. O diagrama tensão x deformação específica ilustra que a inserção com o aplicador gera maiores tensões nas ligaduras elásticas do que a pinça insersora, estas tensões podem ser responsáveis pela quebra das ligações cruzadas o que resulta numa degradação das propriedades físicas do elastômero. / The aim of this work is to determine parameters to evaluate the applying clamp of elastic tie, comparing it with the applicator of elastic tie. It was idealized and constructed a device to measure the displacement force of the elastic tie, being constituded of force and displacement transducers, signals conditioner, data acquisition plate and a computer. To determine the displacement forces, 58 elastic ties had been used, 29 of them being positioned with the applicator and the 29 other on being positioned with the help of the clamp. The results had shown that the ties positioned with the clamp required a bigger displacement force. The measurements of a sample of 45 ties made in a profile projector had shown that the ties positioned with the clamp has strained less during the act of insertion. The stress x strain diagram shows that the insertion made with the applicator creates bigger stress in the elastic ties than the stress when the applying clamp is used. These stress can be responsible for the crossed linking, and in addition results in a degradation in the physical properties of the elastomer.

Orientador: José Elias Tomazini / Banca: João Zangrandi Filho / Banca: Cristiane Aparecida Assis Claro / Resumo: O objetivo do trabalho foi determinar parâmetros para avaliar a pinça insersora de ligadura elástica, comparando-a com o aplicador de ligadura elástica. Foi idealizado e construído um dispositivo para medir a força de deslocamento da ligadura elástica, composto por transdutores de força e deslocamento, condicionador de sinais, placa de aquisição de dados e um computador. Para determinar a força de deslocamento foram utilizadas 58 ligaduras elásticas, sendo 29 ligaduras colocadas com o aplicador e 29 inseridas com a pinça. Os resultados mostraram que as ligaduras colocadas com a pinça necessitaram de uma força de deslocamento maior. As medidas da amostra de 45 ligaduras no projetor de perfil mostraram que a pinça esticou menos as ligaduras elásticas durante a manobra de inserção no braquete. O diagrama tensão x deformação específica ilustra que a inserção com o aplicador gera maiores tensões nas ligaduras elásticas do que a pinça insersora, estas tensões podem ser responsáveis pela quebra das ligações cruzadas o que resulta numa degradação das propriedades físicas do elastômero. / Abstract: The aim of this work is to determine parameters to evaluate the applying clamp of elastic tie, comparing it with the applicator of elastic tie. It was idealized and constructed a device to measure the displacement force of the elastic tie, being constituded of force and displacement transducers, signals conditioner, data acquisition plate and a computer. To determine the displacement forces, 58 elastic ties had been used, 29 of them being positioned with the applicator and the 29 other on being positioned with the help of the clamp. The results had shown that the ties positioned with the clamp required a bigger displacement force. The measurements of a sample of 45 ties made in a profile projector had shown that the ties positioned with the clamp has strained less during the act of insertion. The stress x strain diagram shows that the insertion made with the applicator creates bigger stress in the elastic ties than the stress when the applying clamp is used. These stress can be responsible for the crossed linking, and in addition results in a degradation in the physical properties of the elastomer. / Mestre

The diploma thesis is focused on analysis of degradation process of elastomeric materials which come to contact with certain selected environments. The thesis describes all types of polymer materials along with their properties that specify their area of application, not only in technical practice. The experimental part of the thesis analyzes the intensity and effects of degradation processes of elastomeric materials which come to contact with selected hydrocarbon fuels. The analysis is based on measurements of dimensions, weight and strength characteristics of individual samples with subsequent evaluation of the consequences of the application in particular kinds of environments.

No description available.