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Organisationseinheit der BAM
- 2 Prozess- und Anlagensicherheit (2)
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- 2.2 Prozesssimulation (2)
- 3 Gefahrgutumschließungen; Energiespeicher (2)
- 3.0 Abteilungsleitung und andere (2)
- 7 Bauwerkssicherheit (2)
- 7.5 Technische Eigenschaften von Polymerwerkstoffen (2)
- 8 Zerstörungsfreie Prüfung (2)
- 8.1 Sensorik, mess- und prüftechnische Verfahren (2)
Eingeladener Vortrag
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Relaxation behaviour of thermoplastic polyurethanes with covalently attached nitroaniline dipoles
(2002)
Thermoplastic polyurethanes with covalently attached nitroaniline chromophores exhibit a strong high-temperature relaxation associated with a glass transition rather than the typical frequency-independent loss due to the aggregation of polymer chains via hydrogen bonds. This relaxation behaviour suggests the formation of an amorphous structure without separation into soft-segment and hard-segment phases. In such a structure, a field-induced orientation of molecular dipoles is stabilised by the high viscosity of the material below its glass transition. The dipole orientation yields a pyroelectric effect caused by dipole-density changes upon thermal expansion and contraction.
The changes in phase separation are investigated by varying the chain length of the soft-phase component and studying its influence on the calorimetric, dynamic-mechanical, and dielectrical properties. Good correlation was found between differential scanning calorimetry, dynamic-mechanical analysis and dielectric spectroscopy as well as measured and calculated pyroelectric coefficients. This leads to a uniform picture of the structural changes caused by the incorporation of nitroaniline chromophores into the polyurethane structure.
Degradation effects of automotive coatings after weathering as detected by thermoluminescence
(2004)
Angesichts der spezifischen Bedeutung der Aushärtung von Phenolharzen für ihre Eigenschaften als Ingenieurwerkstoffe besteht großes Interesse an deren quantitativer Charakterisierung. Mittels DSC-Messungen unter hohem Druck (HP-DSC) kann die Vernetzungsreaktion der Phenolharzformmassen durch die Unterdrückung der Verdampfung niedermolekularer Substanzen ohne störende Überlagerungen verfolgt werden. Mittels verschiedener Vernetzungsgrade können die Einflussparameter der Aufheizrate und der Nachtemperung optimiert werden. Die Messergebnisse ermöglichen eine Modellierung der Reaktionskinetik mit dem Ziel einer verbesserten Prozessführung und Qualitätskontrolle in der industriellen Praxis.
Microbial induced corrosion (MIC) is a crucial problem in many technical plants as well as fuel tanks, leading to considerable damage and huge financial losses. Successful prevention of MIC requires the localization of first signs of corrosion as well as the identification of factors influencing the corrosion process. In this respect, also the determination of corrosion rates can be of interest for the possible prevention of MIC. Hence, there is a growing need for sensitive and preferably inexpensive tools that enable the early detection of MIC. Of special interest are methods, which provide spatially and time-resolved information and allow the study of changes on metal surfaces as prerequisites for a more detailed analysis of ongoing corrosion processes at a MIC-affected site.
Biofilm formation can lead to changes in pH, oxygen and chloride concentration as well as to the release of certain metal ions like Fe(II) and Mn(II) depending on the type of metal surface involved. Hence, optical methods enabling the detection of these analytes at very low concentration and monitoring of their changes can be used for MIC detection. Here, we propose to utilize polymeric nanosensors for MIC detection via the determination of the local pH value changes in different biofilms. Such nanosensors are known to have several advantages in imaging applications such as intracellular pH measurements including the ease of doping or labeling with a multitude of analyte-responsive and inert dye molecules for the realization of a high analyte sensitivity and ratiometric sensing. Moreover, they can be surface functionalized with target-specific ligands e.g., lectins, for the specific binding to the outer surface of certain types of bacteria. In this respect, different polymer architectures will be studied to identify an optimal candidate in terms of imaging performance in conjunction with several classes of pH-responsive fluorescent dyes like cyanines, aza-BODIPYs, and xanthenes, utilizing different mechanism of signal generation such as photo-induced electron transfer or protonation-induced changes in the spectral position of absorption and emission spectra.
Microbial induced corrosion (MIC) is a crucial problem in many technical plants as well as fuel tanks, leading to considerable damage and huge financial losses. Successful prevention of MIC requires the localization of first signs of corrosion as well as the identification of factors influencing the corrosion process.1 Hence, there is a growing need for sensitive and preferably inexpensive tools that enable the early detection of MIC. Of high importance are methods, which provide spatially and time-resolved information and allow the study of changes on metal surfaces as prerequisites for a more detailed analysis of ongoing corrosion processes at a MIC-affected site.2 In this respect, also the determination of corrosion rates can be of interest for the possible prevention of MIC.
Microbial induced corrosion (MIC) is a crucial problem in many technical plants as well as fuel tanks, leading to considerable damage and huge financial losses. Successful prevention of MIC requires the localization of first signs of corrosion as well as the identification of factors influencing the corrosion process.1 Hence, there is a growing need for sensitive and preferably inexpensive tools that enable the early detection of MIC. Of high importance are methods, which provide spatially and time-resolved information and allow the study of changes on metal surfaces as prerequisites for a more detailed analysis of ongoing corrosion processes at a MIC-affected site.2 In this respect, also the determination of corrosion rates can be of interest for the possible prevention of MIC.