Communicating about the Graphic Novel – a Series of Workshops

The graphic novel as a development of the last decades and now an independent art form is the focus of this text. A graphic novel workshop series is presented as an example. This took place within the framework of a teacher-training course in the Saharan refugee camps in Algeria. With the possibilities of the graphic novels, contents from the professional field of the participants were developed by means of art education and design, in the sense of reflecting their own work events, the work reference, for themselves and for others. Self-created stories from day-to-day business were developed in detail in the form of successive pictures and picture elements, partly by incorporating writing

Multi-scale simulation of degradation of polymer coatings: Thermo-mechanical simulations

In this work we simulate the full sequence of steps that are also typically performed in an experimental approach when studying photo-degradation of a polymer coating, namely, i) sample preparation, ii) photo-degradation and iii) thermo-mechanical analysis of the material during photo-degradation. In the current paper, we focus on performing several molecular dynamics simulations to study the thermo-mechanical properties of a virgin thermoset coating as well as degraded ones. Using an atomistic structure that is obtained by fine-graining the mesoscopic structure, we obtain consistent correlations between the simulated thermo-mechanical properties of the material and those measured experimentally. In addition, it is shown that by using oscillatory strain fields in MD - instead of the commonly applied linear tensile/compression strain fields - one can acquire greater knowledge on the structure-property relation of polymeric materials. Eventually, we show that our simulation approach gives rise to a remarkable insight into the mechanism of the photo-degradation process

Miscibility and Specific Interactions in Blends of Poly(N-vinyl-2-pyrrolidone) and Acid Functional Polyester Resins

Miscibility and intermolecular interactions of novel blends of poly(N-vinyl-2-pyrrolidone) (PVP) and acid functional polyester resins (APE) were studied by use of Differential Scanning Calorimetry (DSC), Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR), Cross-Polarization Magic Angle Spinning (CPMAS) 13C NMR spectroscopy and 1H NMR relaxometry. The miscibility is found to be correlated to the number of acid end groups (acid value, AV) of APE and the molar mass (M) of PVP. Blends of APE with high AV and PVP with high M exhibit single-phase behavior in DSC and 1H NMR. Both ATR-FTIR and 13C NMR of these blends show composition-dependent displacements of the APE and PVP signals, which confirms that the two polymers are close together in the blend. In particular, FTIR spectra reveal a systematic blue shift of the stretch vibrations of both PVP and APE carbonyl groups. This indicates dipole−dipole interactions between a carbonyl group of PVP and a carbonyl of APE. The spectra contain a broad peak at about 1630 cm−1, which appears as a shoulder of the carbonyl stretch vibration of PVP. This band is ascribed to hydrogen bonding between the carbonyls of PVP and the hydrogen atoms of the end groups of the APE resins. Analysis of temperature-varied FTIR spectra of blends of PVP and a polyester resin of neopentyl glycol and isophthalic acid (PNI), used as a model of the APE resin, confirms the existence of such interactions.status: publishe

Aqueous friction behavior of swollen hydrophilic poly(ethylene glycol)-based polyurethane coatings

The macroscopic friction behavior of water-swollen cross-linked poly(ethylene glycol)-based polyurethane coatings (PEG-based PU coatings) with varying PEG precursor mass is measured against a glass counter surface. Experimental data such as the water uptake and the indentation modulus are used to calculate an accurate value for the molar mass between cross-links Mc, which, in turn, is used for the estimation of the actual coating mesh size ξ. The friction, swelling and indentation data obtained are used to successfully deduce an empirical model for the quantitative description of the aqueous friction behavior of these coatings depending on the mesh size of the coatings and the sliding velocity only

The influence of the exposure conditions on the simulated photodegradation process of polyester-urethane coatings

A kinetic Monte Carlo method to simulate photodegradation of a polymer coating is applied to the weathering process of a polyester-urethane clearcoat during artificial exposure under different conditions. Firstly, the optimised simulation parameters that yield the best match with experimentally measured results on the depth-resolved ester and urethane bond fractions are determined and compared for two different aerobic exposure experiments (one in a Weather-Ometer (WOM) and one in a Suntest equipment). Secondly, several other quantities that are obtained from the simulations, but cannot be determined experimentally, are compared, such as the fraction of newly formed crosslink bonds, absorptivity states, oxidised states, the fraction of radicals, the concentration of oxygen and the total amount of remaining material. Depth-inhomogeneity of the rate of photon absorption leads to the formation of distinct depth gradients in the WOM simulation, while a much more homogeneous evolution is obtained for the Suntest-air simulation. Photo-oxidative damage in the WOM simulation is more concentrated on the upper layer of the coating, resulting in the extensive evaporation of highly oxidised material, whereas degradation in the Suntest-air simulation is more spread out over the entire coating thickness, resulting in less material loss

Design of dual hydrophobic–hydrophilic polymer networks for highly lubricious polyether-urethane coatings

Bio-lubricated surfaces found in nature have inspired the design of low friction polymer coatings for biomedical applications. This work presents a systematic study of the relation between the network structure parameters and the macroscopic friction properties of highly lubricious dual hydrophobic/hydrophilic polyurethane (PU) coatings in an aqueous environment. Chemically cross-linked PU coatings were prepared by adding poly(ethylene glycol) mono-methyl ether (mPEG) as hydrophilic dangling chains, or poly(ethylene glycol) (PEG)-diol as hydrophilic elastically active network chains, to poly(propylene glycol) (PPG)-PU coating formulations. The friction behaviour of the water swollen coatings was measured using a custom-made water immersed tribology setup. Addition of the PEG segments or mPEG dangling chains to hydrophobic PPG coatings greatly enhances the lubricious properties of the coatings. These dual hydrophobic/hydrophilic diol PU network exhibit a surface with a lower coefficient of friction compared to reference coatings from either individual precursors, demonstrating a large synergistic effect between the hydrophobic PPG and the hydrophilic PEG in the coatings. Based on network structure and surface chain considerations it is hypothesized that the existence of a thin and softer hydrated surface layer on top of a less hydrated, more rigid, coating bulk layer gives rise to the observed enhanced lubricious properties, hereby mimicking to some extent bio-lubricated systems, such as cartilage