Charakterisierung von Elastomeren mittels dynamischer Indentation und vergleichender Methoden

This doctor thesis presents the indentation method, and its application for elastomer testing is demonstrated using NR/SBR systems. The data of the indentation measurements and force/indentation diagrams are evaluated, faults and artefacts as well as effects of temperature and fillers are considered, and NMR and DMTA measurements have been carried out to confirm the results.SIGLEAvailable from: http://sylvester.bth.rwth-aachen.de/dissertationen/2002/107/index.htm / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Bioabbaubare Polymernetzwerke mit Formgedaechtniseffekt als Matrix fuer Wirkstofffreisetzungssysteme

This thesis describes the development and characterization of matrix systems based on biodegradable polymer networks with shape-memory properties for controlled delivery of low molecular mass drugs. A polymer network based on oligo[(#epsilon#-hydroxycaproate)-co-glycolate]-dimethacrylates and butylacrylate with a semi-crystalline switching segment is used for the systematic investigation of the influence of the polymer matrix on drug release. A direct comparison with copoly(esterurethane)networks of oligo[(rac-lactate)-co-glycolate]tetrols and diisocyanate as polymer matrix gives information about the influence of the type of cross-linkings on drug release. In addition, copoly(esterurethane) networks of oligo[(#epsilon#-hydroxycaproate)-co-glycolate]tetrols and diisocyanate with an amorphous switching segment are evaluated. The antimicrobial drugs ethacridin lactate, nitrofurantoin and enoxacin are incorporated into the polymer matrix by swelling the polymer networks in a solution of the drug, followed by a quantitative displacement of the solvent. The drug loading of the materials varies between 0,1 mass-% and 2,4-mass% depending on the swelling degree of the polymer networks, the solubility of the drugs in the polymer matrix and the solvent. Additionally, ethacridin lactate is incorporated into the polymer networks by homogenous dispersion in the oligo[(#epsilon#-hydroxycaproate)-c-glycolate]dimethacrylates followed by photochemical crosslinking in situ. A drug concentration in the polymer matrix between 0,2 mass-% and 5,7 mass-% is realized by this loading technique. (orig.)Available from: http://sylvester.bth.rwth-aachen.de/dissertationen/2003/148/index.htm / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Entwicklung photosensitiver Polymernetzwerke mit Formgedaechtniseigenschaften

In the present thesis a polymer system with shape-memory properties is developed. The shape-memory effect is triggered by irradiation of the polymer with UV-light with different wavelength. The irradiation causes a reversible change of network density of the elastomer. By that, the elastic properties of the material are changed in a way that the fixing of a temporary shape by UV-irradiation is possible. Irradiation of the fixed sample with another UV-light releases the fixing and the permanent shape of the polymer sample is recovered. The light triggered one-way shape-memory effect for polymers has been realized for the first time.SIGLEAvailable from: http://www.deposit.ddb.de/cgi-bin/dokserv / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Entwicklung von Labormethoden zur Prognose des mikrobiellen Selbstreinigungspotentials kontaminierter Grundwaesser und Boeden

Laboratory methods will be developed and optimised for assessing the microbiological background potential and forecasting the possible course of biological self-cleaning processes. A microcosmos experiment with batch cultures will provide information on reaction conditions, preferably by measurements of external parameters like CO2 production and O2 consumption of the microbial breathing processes. The need for further parameters for validating the test will be checked. The results of the short-term and long-term breathing tests with soil samples taken in different depths of a well and long-term breathing tests with groundwater will provide information on the self-cleaning potential of a given site.Es sollen Labormethoden entwickelt und optimiert werden, mit denen das mikrobiologische Potential im Untergrund abgeschaetzt werden kann und die eine Prognose ueber den moeglichen Ablauf von biologischen Selbstreinigungsprozessen erlauben. Dies soll auf der Grundlage von Batch-Kulturen als Mikrokosmosversuch erfolgen, um die Einstellung und den direkten Vergleich verschiedener Reaktionsbedingungen zu ermoeglichen. Der Versuchsverlauf soll vorzugsweise ueber die Messung externer Parameter wie der CO2-Produktion und dem O2-Verbrauch der mikrobiellen Atmungsprozesse zu beobachten sein bzw. bei anoxischen Versuchsbedingungen ueber den Elektronenakzeptorverbrauch; ferner soll die Notwendigkeit weiterer Parameter zur Validierung der Testaussage ueberprueft werden. Abschliessend soll durch den Vergleich der Ergebnisse der Kurzzeit- und Langzeitatmungstests mit Bodenproben aus verschiedenen Tiefen eines Brunnens sowie der Langzeitatmungstests mit Grundwasser eine Prognose ueber das Selbstreinigungspotential eines Standortes moeglich werden.SIGLEAvailable from: http://deposit.ddb.de/cgi-bin/dokserv?idn=966050681 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

RTM Untersuchungen an zweidimensionalen Nanostrukturen am Beispiel der reinen Au(100)-Oberflaeche und des selbstassemblierten Systems Sauerstoff auf Cu(110)

In this STM study, nanostructures on metallic single crystals are observed under UHV conditions. The aim of the work at the Au(100)-surface is to evaluate an energetic quantity, namely the step free energy, from a topographic structure information. Adatom and vacancy islands are produced on the tempered reconstructed Au(100)-surface by evaporation of submonolayer quantities of gold and sputtering with Argon ions, respectively. The decay of these islands is correlated with a decrease of the aspect ratio to approximately 1. After that the aspect ratio varies merely stochastically around this mean value. We could observe adatom islands at T=353 K, which neither grow nor decay over a long period of time and whose aspect ratio varies stochastically around the mean value of 1. In conclusion, we assume that these islands are in a thermodynamic equilibrium situation or at least close to it. By averaging over these island shapes, we obtain the equilibrium shape for this temperature. From island shape fluctuations we make a quantitative determination of the mean step free energy to 170 meV per atom. In completely separated experiments from the described ones above, the formation of the so-called (2 x 1) oxygen stripe phase on Cu(110) is imaged in situ, and simultaneously a quantitative determination of the induced surface stress is accomplished. (orig.)SIGLEAvailable from: http://deposit.ddb.de/cgi-bin/dokserv?idn=973322225 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Grenzflaechen-Analyse durch Mie-Plasmon-Spektroskopie an Edelmetallclustern

In this thesis the study of interband transitions and interface phenomena by means of small clusters is described. The clusters were studied by means of optical resonance-absorption spectroscopy. Especially silver clusters deposed on Al_2O_3, TiO_2, Cr_2O_3, In_2O_3, ans SiO_2 substrates and embedded in Al_2O_3, Sb_2O_5, TiO_2, SrTiO_2, SnO_2, In_2O_3, C_6_0, Si, and SiO_2 matrices and gold clusters were studied. Finally the measurement of the electric conductivity of thin, cluster-coated silver films is described. (HSI)SIGLEAvailable from TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Plasmagestuetzte Oberflaechenmodifizierung von Polypropen

The employment of polypropylene in clothing industry is restricted due to its low dye absorption. An increase in wettability of polypropylene fibers and a simultaneous increase of the interaction between dyes and fibres should be suitable procedure in order to increase the dye absorption. The author investigates the possibilities of plasma-assisted hydrophilization in order to improve the colouring properties. There is an increased water wettability of the surface of polypropylene in comparison to the untreated material with an increase in time of treatment in oxygen plasma, with an increase of the microwave input and with decreasing distance between probe material and microwave input. The degree of hydrophilization of polypropylene fibres treated by barriere discharge increases with increasing exposition time nearly being independent of the microwave performance. The oxygen supply does not influence the wettability during the plasma-assisted hydrophilization. The wettability of the surface of propylene foils decreases with increasing storage at atmosphere due to a reorientation of the plasma induced functional groups towards the interior of the foils. The wettability of plasma-assisted propylene foils in water nearly is unchanged. The functional groups are on the surface. With increasing duration of treatment in oxygen plasma and in barriere discharges, there is an increase of oxygen containing functional groups in the surface of polypropylene foils. XPS experiments at oxygen plasma treated polypropylene foils increases and then decreases with increasing duration of storage. This decrease is due to a reorientation of the oxygen containing groups from the surface into the bulk medium. With increasing duration of treatment, the surface roughness of the probe increases leading to a reduction of the contact angle with water and to an increase of the oxygen content in the surface. Beside the plasma induced insertion of oxygen containing groups, the author observes plasma induced etching processes resulting in degradation substances. The author also investigates the mount behavior of the dispersion colour Resolin Red FB and the mount behavior of the solution colours Sudan Blue II and Sudan Red B on polypropylene fibres treated by oxygen plasma and barriere discharge, respectively. The mount performance of all three colours on plasma treated fibres is greater in comparison to untreated materials. Polypropylene fibres treated by barriere discharge do not show this behavior due to the low degree of hydrophilization of the fibre surface. Sudan Blue II has the highest mount rate according to untreated and plasmatreated polypropylene fibres.SIGLEAvailable from: http://deposit.ddb.de/cgi-bin/dokserv?idn=966432460 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Instabilitaeten und spontane Symmetriebrechung in zweidimensionalen Fermisystemen

In this thesis the Pomeranchuk and the Cooper instability for Fermi liquids is considered. After a description of the superconducting state by means of the renormalization group the application to the two-dimensional Hubbard model is studied. (HSI)SIGLEAvailable from: http://deposit.ddb.de/cgi-bin/dokserv?idn=967673313 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Messung der qql#nu#-Endzustaende der W-Paar-Produktion bei Schwerpunktsenergien von 183 GeV bis 202 GeV mit dem L3-Detektor bei LEP

The flavour-independent selection was applied to the data obtained with the L3 detector from 1997 to 1999 with a c.m. energy from 183 to 202 GeV and used for the determination of the production cross sections, the branching ratios, the mass, and the decay width of the W boson. For the branching ratios resulted following values as mean values of the measurements of all considered c.m. energies: BR_W_#->#_e_#nu#=10. 58#+-#0.37 %, BR_W_#->#_#mu#_#nu#=9.57#+-#0.36 %, BR_W_#->#_#tau# _n_u=11.91#+-#0.48 % without assumption of lepton universality as well as BR_W_#->#_l_#nu#=10.69#+-#0.16 % with lepton universality. After a kinematical fit the W mass and W decay with are extracted. as whole result of this fit to the events selected by the present analysis from all considered energies and lepton types results: M_W= 80.34#+-#0.09 GeV and #GAMMA#_W=2.14#+-#0.21 GeV.SIGLEAvailable from: http://sylvester.bth.rwth-aachen.de/dissertationen/2000/ / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Messung der Myonpaarproduktion im Prozess e"+e"-#->##mu#"+#mu#"-(#gamma#) bei Schwerpunktsenergien von 89 GeV bis 183 GeV

At different c. m. energies the total cross section and the forward-backward asymmetry were measured. To the measurements parametrization of the standard model are fitted in order to determine the mass and the width of the Z resonance as well as the vector and axial-vector coupling constants of the muon to the Z.SIGLEAvailable from: http://sylvester.bth.rwth-aachen.de/dissertationen/2001/ / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman