Abstract: In this work we present the investigations on the blackening of the outer jacket of the
High Pressure Sodium (HPS) lamps. For this purpose ceramic arc tubes and their glass outer jackets
taken from lamps burned for different times (0h-10000h) were examined by X-ray Photoelectron
Spectroscopy (XPS) and Secondary Ion Mass Spectroscopy (SIMS) in order to determine the
composition of the deposit on the internal wall of glass outer jacket. In the case of the several
thousand hours burned lamps the outer bulb was found to be covered by aluminium, which comes
to a black deposit on the glass surface. XPS identified Al on the glass surface can be found in two
different chemical state (elemental Al, Al2O3). The assumed evaporation of aluminium-oxide
ceramic tube might be described by a dissociative mechanism of the alumina evaporation. This
papers described the possible mechanism of the alumina evaporation. Na was also found in the
black deposit, whose cause of this in the case of the several thousand hours burned lamps is
probably related to the sodium transport through the walls of the arc tube
Abstract: Obtaining ceramic bodies with enhanced mechanical properties via colloidal processing
requires efficient dispersion of the ceramic powders. In this work, the dispersive effect of three low
molecular weight quaternary ammonium hydroxides with different alkyl groups upon stabilisation
of CuO aqueous suspensions is studied and compared with that of Tiron, a compound based on the
benzene molecule. The purpose is to illustrate the effect of molecular structure, size and charge
location upon dispersing effectiveness. To access these parameters, rheological and electrophoretic
measurements using both bare and surface charge modified CuO were made. Tiron® revealed to be
the most efficient dispersant for CuO in water, rendering viscosity values below 1 Pa⋅s and the
highest variation in zeta potential amplitude.
Abstract: The determination of electrokinetic properties such as the zeta-potential of polymer
samples with classical methods is laborious and time-consuming. For this reasons, a reliable, fast,
and easy to use measurement system based on streaming potential measurement was developed. In
this novel measurement system, streaming potential is created by an oscillating flow of a small
amount of electrolyte solution through the sample media. In addition, this setup allows direct
titration and therefore time-resolved monitoring of changes in zeta-potential in a seconds timescale.
With this instrument, the concentration- as well as the time-dependent adsorption behaviour of
various non-ionic, anionic and cationic surfactants on a novel, regenerated cellulosic polymer was
investigated. This new cellulose-based, fibrous textile polymer is permanently cationised, not only
at the surface but throughout the whole fibre.
The results show that even very low concentrations of surfactant, due to its charge and chemical
composition, highly influence the surface charge of the polymer in a large range. Furthermore, the
results for this new textile material are compared with other textile fibres, e. g. wool.
Abstract: Growing awareness of dangers related to NOX emission by industry and road
transportation has resulted in increasing demand for sensors detecting NOX. An important class of
these sensors use Pt-based electrodes applied on yttria-stabilized zirconia (YSZ) substrates.
Performance of such sensors depends on redox reactions occurring at electrodes in the tested
atmospheres. Impedance spectra and j-U curves of PtRh electrodes were measured in a 3-electrode
mode, using Pt metal pads as counter and reference electrodes. The data were collected in a 10mHz-
100kHz frequency range at temperatures from 450 to 750°C. Each series of measurements was
carried out in a gas mixture with different oxygen content ranging from 0 to 21 vol%. It was found
out that the low-frequency part of the impedance spectra (characterizing electrode processes) was
sensitive to the oxygen content in the gas mixtures.
Abstract: Degussa P-25 TiO2 powder was used as a catalyst in the photocatalytic oxidation of
organics. With the objective of promoting a more effective electron-hole separation upon
irradiation, the catalyst was modified with small amounts of platinum. Characterisation of the
powders was done by X-Ray diffraction and SEM. Chloroform was used as a model molecule and
its degradation followed using selective electrodes, with excellent results for the modified titania.
Langmuir-Hinselwood kinetic was used to describe the heterogeneous oxidation of chloroform on
TiO2, for low solute concentrations.
Abstract: Dense ceramic anodes of perovskite-type La1-x-ySrxCo1-zAlzO3-δ ( x = 0.45-0.70; y = 0-
0.05; z = 0-0.20) and K2NiF4-type La2Ni1-xMexO4+δ (Me = Co, Cu; x = 0-0.20), synthesized by the
glycine-nitrate technique, were assessed for oxygen evolution in alkaline media. The lowest
overpotentials are observed for (La0.3Sr0.7)0.97CoO3-δ, which exhibits a significant oxygen deficiency
in combination with high conductivity associated with the A-site cation nonstoichiometry
compensation mechanism via Co4+ formation. Perovskite-type cobaltite anodes are essentially
stable in alkaline solutions, whilst La2NiO4-based electrodes exhibit degradation at the potentials
where the oxygen evolution occurs, probably due to the electrochemical oxygen intercalation in the
Abstract: We present results concerning the characterization of selected silica-based materials from
a molecular modeling approach, together with some physical and mathematical tests to check the
reliability of the obtained results. The experimental adsorption data is used in combination with
Monte Carlo simulations and a regularization procedure in order to propose a reliable Pore Size
Distribution (PSD). Individual adsorption isotherms are obtained by Monte Carlo simulations
performed in the Grand Canonical ensemble. The methodology is applied to M41S materials,
chosen due to their well defined pore geometry and pore size distribution, obtainable from
alternative procedures. Our results are in excellent agreement with previous published results,
demonstrating the reliability of this methodology for the characterization of other materials, with
less well-defined structural properties.
Abstract: Deposition of thin plasma polymer films as final layer on organic coatings can provide
one promising solution to tailor the surface properties offering third functionality and increased
The present work is dedicated to the study of the barrier properties of polyurethane coil coatings
modified by different plasma polymerization processes. Microwave (MW) and radio frequency
(RF) plasmas were used to deposit thin films with different composition from various precursor
mixtures. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) were used
to reveal the evolution of the plasma treated coil coatings during weathering tests. Electrochemical
impedance spectroscopy (EIS) was employed to study the barrier properties of the coatings.
The results show a degradation effect of the plasma treatment on the barrier properties of the coil
coatings especially in the case of the oxygen-containing plasmas. However addition of a fluorinecontaining
component to the precursor mixture leads to the elimination of the negative effect of the
plasma treatment on the barrier properties of the coil coatings. The fluorine-containing films exhibit
higher weathering stability in comparison with the fluorine-free ones.
Abstract: Polymer extrusion is one of the most important polymer processing techniques.
Modelling of the phenomena developing inside single screw extruders enabled the development of
commercial software which can be used to study the performance of existing systems and to define
the equipment characteristics for new applications.
Although mixing is one of the most important performance measures of extrusion, it is usually
disregarded in the available programs. Consequently, in this work mathematical models for
quantifying mixing in single screw extruders are developed and subsequently inserted in a global
computer modelling program of single screw extrusion. The mixing model quantifies distributive
and dispersive mixing and coalescence mechanisms in a liquid-liquid system. This is accomplished
by calculating the variation of the thickness of drops considered to be suspended in the polymeric
matrix, taking into account the rate and drop break-up time and the coalescence probability.
The influence of several parameters, such as viscosities, initial drop dimension, screw speed and
barrel temperature, are examined
Abstract: The local cyclic elastic-plastic stress-strain responses were simulated using the
incremental plasticity procedures of ABAQUS finite element code. It is shown a better
understanding on the evolutions of the local cyclic stress-strain and the strong interactions between
the most stressed material element and its neighboring material elements in the plastic deformations
and stress redistributions. Based on the stress/strain states of the stabilized cycle, a new damage
parameter, proposed on modification of the ASME code parameter, is applied and improved
correlations between the predicted and the experimental fatigue lives are shown. It is concluded that
the improvement of fatigue life prediction depends not only on the fatigue damage models, but also
on the accurate evaluations of the cyclic elasto-plastic stress/strain responses.