Im Mittelpunkt der Dissertation stehen räumlich-statistische Verfahren zur Charakterisierung der Verteilung von Füllstoffen (Ruß oder Silica) innerhalb der Polymermatrix von gefüllten Elastomeren. Das Variogramm und andere Zufallsfeldcharakteristiken werden dazu benutzt, um die in TEM-Aufnahmen von Dünnschnitten gefüllter Elastomere sichtbar werdende Füllstoffverteilung statistisch zu beschreiben. Mit Hilfe von Shot-Noise-Prozessen wird eine Verbindung zwischen der räumlichen Verteilung der kugelförmigen Füllstoffprimärpartikel und den TEM-Aufnahmen hergestellt. Mit einer stochastischen Optimierungsmethode kann das System der auf die Bildebene projizierten Primärpartikel auch aus TEM-Aufnahmen rekonstruiert werden, was zu einer robusten Charakterisierung der Füllstoffdispersion führt. Weitere wichtige Punkte der Arbeit stellen die statistische Charakterisierung einzelner Füllstoff-Aggregate sowie die Untersuchung der spezifischen Euler-Zahl des polymeren Netzwerkes dar.

Aachen, Techn. Hochsch., Thesis (doctoral), 2001.

This thesis is motivated by the use of full-depth, precast, prestressed concrete panels to facilitate deck replacement of composite bridges. The shear pockets required in using convention shear stud connections, however, can cause durability problems. The objective of this study is to investigate the possibility of eliminating the use of shear studs, and adhesively bond the concrete and steel sections. The feasibility of the developed polyurethane adhesive joint is defined based on the serviceability and ultimate limit states. The joint must have sufficient stiffness that additional deflection due to slip must not be excessive. The adhesive and bond must also have sufficient strength to allow the development of the full plastic capacity of the composite section. The use of the developed adhesive joint in typical composite bridges was found to be feasible. The behaviour under live load was found to be close to a fully composite section.

This thesis is motivated by the use of full-depth, precast, prestressed concrete panels to facilitate deck replacement of composite bridges. The shear pockets required in using convention shear stud connections, however, can cause durability problems. The objective of this study is to investigate the possibility of eliminating the use of shear studs, and adhesively bond the concrete and steel sections. The feasibility of the developed polyurethane adhesive joint is defined based on the serviceability and ultimate limit states. The joint must have sufficient stiffness that additional deflection due to slip must not be excessive. The adhesive and bond must also have sufficient strength to allow the development of the full plastic capacity of the composite section. The use of the developed adhesive joint in typical composite bridges was found to be feasible. The behaviour under live load was found to be close to a fully composite section.

Zugl.: Aachen, Techn. Hochsch., Diss., 2008.

Techn. Hochsch., Diss., 2001--Aachen.

Techn. Hochsch., Diss., 2004--Aachen.

O objetivo deste trabalho é o de caracterizar o processo de condução do EPDM e de formulações deste material quando nele se incorpora diferentes concentrações de trihidróxido de alumínio (alumina trihidratada). Dois procedimentos experimentais foram utilizados para se obter os resultados: o primeiro utilizando medidas de corrente no estado estacionário variando-se a espessura das amostras, o potencial, o material do eletrodo e a temperatura e o segundo através de medidas da distribuição de cargas elétricas no interior do material empregando o método de propagação de um pulso de pressão. Na análise dos resultados experimentais encontrou-se presença de polarização elétrica e de condução, a qual apresenta dependência linear do logaritmo da condutividade com a raiz do campo, na região de altos campos elétricos. Estudo comparativo de alguns modelos foi realizado sem que nenhum deles explicasse os nossos resultados. Propusemos tentativamente a combinação de efeitos de superfície e de volume. Para o material com crescente concentração de alumina também se encontrou dependência da condutividade com a raiz do campo, mas a interpretação dos resultados ficou mais incerta. Além disto, um efeito quadrático com a concentração de alumina foi encontrado para a polarização e para a condução um efeito linear / This work attempts to characterize the processes of electric conduction in the EPDM copolymer and its composites with several contents of alumina trihydrate filler. Two different experimental procedures were employed: (i) measurements of the steady state electric current for several sample thicknesses, applied voltages, temperatures, and different types of electrode (ii) charge distribution measurements using the pressure wave propagation method. The results showed that there is an electric polarization superimposed to an electric conduction. For high electric fields a linear dependence of the log of the conductivity versus the square root of the electric field was found. Several theoretical models were employed aimed at explaining the experimental results but none gave satisfactory results. It seems that the most adequate model is one in which both surface and bulk processes are considered. When the content of alumina trihydrate filler was increased, a linear dependence between the logs of conductivity against the square root of the electric field was again observed, though the results could not be readily interpreted. It was also found that the electric polarization and the electric conductivity show a quadratic and a linear dependence on the alumina trihydrate content, respectively

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