Applied Rheology: Publications

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Tim Phillips
The British Society of Rheology Midwinter Meeting: Complex Fluids and Complex Flows

Appl. Rheol. 22:2 (2012) 104-105

Cite this publication as follows:
Phillips T: The British Society of Rheology Midwinter Meeting: Complex Fluids and Complex Flows, Appl. Rheol. 22 (2012) 104.

Ulrich Alexander Handge, Alexander Kutter
2. Bayreuther Kompetenztage: Rheology, morphology and fracture mechanics of polymers

Appl. Rheol. 22:2 (2012) 102-103

Cite this publication as follows:
Handge UA, Kutter A: 2. Bayreuther Kompetenztage: Rheology, morphology and fracture mechanics of polymers, Appl. Rheol. 22 (2012) 102.

Roberto Cesar de Oliveira Romano, Rafael Giuliano Pileggi
Temperature's role in the rheological behavior of cementitious pastes prepared with air-entraining admixtures

Appl. Rheol. 22:2 (2012) 24333 (6 pages)

Cementitious pastes prepared with air-entraining admixtures (AEA) are very sensitive to mix procedures and environmental conditions. Some of the effects of AEA on the properties of cementitious material are discussed in literature, although for the most part, only in the hardened state. However, the impact temperature has on air-incorporation during the early age stages and on consolidation has been little investigated and as such, is the objective of this work. Thus, pastes formulated with Portland cement and air-entraining admixtures are evaluated in this work with a focus on the role temperature plays in the early age behavior. The results show that air-incorporation was affected by environmental conditions which caused changes in the kinematic viscosity and rate of consolidation.

Cite this publication as follows:
deOliveiraRomano RC, Pileggi RG: Temperature's role in the rheological behavior of cementitious pastes prepared with air-entraining admixtures, Appl. Rheol. 22 (2012) 24333.

Manuel Navarro-Gonzalez, Manfred H. Wagner
Storage stability of bitumen modified by the addition of ground rubber, swollen SBS and polymeric short fibers

Appl. Rheol. 22:2 (2012) 24691 (11 pages)

Bitumen is used as binder for asphalted roads worldwide. However the service life of asphalt roads is limited due to the viscoelastic properties of bitumen. The lack of yield stress and the flow behavior at high temperatures as well as the stiffness of bitumen at lower temperatures results in the main failure sources of asphalt roads. Many polymers have been used in industry to improve the rheological behavior of bitumen and consequently, service life of roads. The polymers are commonly added to hot bitumen under stirring in order to achieve a stable dispersion. However, most polymers show little to no miscibility in bitumen, which requires long dispersion times and may lead to oxidation of bitumen and degradation of the polymers. Poor miscibility of the dispersed polymer and the bitumen matrix can result in phase separation during transport of molten bitumen, leading to a heterogeneous binder and further failure of the paved road, which is a common problem in the paving industry. Rubber pre-treating leads to a faster mixing process without compromising dispersion quality and stability. Bitumen was modified with SBS, ground rubber and chopped fibers of polymers. These fibers, which showed good stability, can be considered for the future as bitumen modifiers. To evaluate the stability of the modified bitumen, we propose a stability index.

Cite this publication as follows:
Navarro-Gonzalez M, Wagner MH: Storage stability of bitumen modified by the addition of ground rubber, swollen SBS and polymeric short fibers, Appl. Rheol. 22 (2012) 24691.

Stephan Laske, Andreas Witschnigg, Hannelore Mattausch, Milan Kracalik, Gerald Pinter, Michael Feuchter, Guenther Maier, Clemens Holzer
Determining the ageing of polypropylene nanocomposites using rheological measurements

Appl. Rheol. 22:2 (2012) 24590 (9 pages)

The principle of silicate layer reinforcement in a polymer matrix is known as the formation of a 3D network of single layers. Nevertheless there is still a lack of knowledge about the physical ageing of nanocomposites respectively the stability of this network over time. As most of the nanocomposite applications have a more or less long-term shelf life respectively storage time, the investigation of the storage-time dependent behavior of the layered 3D structure in a polymer matrix is of major interest. In this study, the rheological (shear and elongational) properties of different polypropylene nanocomposites were measured using a cone-plate rheometer and a Rheotens apparatus. To evaluate the structural stability over time, the samples were measured immediately after processing and after defined periods (18 and 36 months) stored under constant conditions. Furthermore the network structure was determined using XRD and TEM measurements. The results show, that, depending on the clay rate and especially the degree of exfoliation, the rheological properties are changing significantly. Thereby chain splitting caused by photo-oxidative degradation, leading to a loss in molecular weight, as well as a weakened 3D network by reverse diffusion of the polymer chains out of the clay gallery and/or reagglomeration of the nanoparticles are the two main factors.

Cite this publication as follows:
Laske S, Witschnigg A, Mattausch H, Kracalik M, Pinter G, Feuchter M, Maier G, Holzer C: Determining the ageing of polypropylene nanocomposites using rheological measurements, Appl. Rheol. 22 (2012) 24590.


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