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101.
O. Werzer B. Stadlober A. Haase M. Oehzelt R. Resel 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,66(4):455-459
Pentacene thin films with thicknesses ranging from 10 nm to
180 nm are investigated by specular X-ray diffraction in the
reflectivity regime and in the wide angular regime. The results of
the reflectivity measurements show a clear shift of the 001
reflection of the thin film phase depending on the layer thickness.
It is shown that this shift can be explained by the dynamical
scattering theory. The wide angular regime measurements show the 00L
of the thin film phase. Williams-Hall plots are used to extract
information on the crystallite size and mean micro strain of the
thin film phase. The crystallite size is in good agreement with the
results obtained by the reflectivity measurements. From this it can
be concluded that the thin film phase crystallites are extended over
the entire film thickness down to the substrate. Additionally an
increase of the micro strain with increasing film thickness is
observed. 相似文献
102.
Vertically aligned monodomain nematic liquid-crystal elastomers contract when heated. If a temperature gradient is applied
across the width of such a cantilever, inhomogeneous strain distribution leads to bending motion. We modelled the kinetics
of thermally induced bending in the limit of a long thin strip and the predicted time variation of curvature agreed quantitatively
with experimental data from samples with a range of critical indices and nematic-isotropic transition temperatures. We also
deduced a value for the thermal diffusion coefficient of the elastomer. 相似文献
103.
Shape transformation of thin two-dimensional sheets into three-dimensional structures using light is of great interest for remotely controlled fabrication, surface modulation, and actuation. Over the last few decades, significant efforts have been made to develop material systems incorporating photochemical or photothermal elements to drive deformation in response to illumination. However, the full extent of the interplay between chemistry, optics, and mechanics in these materials is poorly understood. In this review, we introduce principles of shape morphing in these systems by considering the underlying physics of photoinduced stresses and how these have been used in recent literature. In addition, we provide a critical overview of the important design characteristics of both photochemical and photothermal system and offer our view on the open opportunities and challenges in this rapidly growing field. 相似文献
104.
H. Medhioub H. Smaoui C. Zerrouki J.J. Bonnet 《Journal of Physics and Chemistry of Solids》2008,69(10):2476-2480
Infrared (IR) spectroscopy, dielectric spectroscopy (DS), and thermally stimulated depolarization current (TSDC) have been used to study heat treatment effects on an epoxy-based polymer. Variations in physico-chemical and dielectric properties were examined for annealing temperatures between 55 and 170 °C. IR results have shown that heating causes both chain scission and thermal oxidation of the polymer, increasing thus the amount of trapped charges. The complex dielectric permittivity and the dielectric modulus have been analyzed, by means of DS, to highlight and separate charge relaxation phenomena from conduction contributions. Results indicate structural rearrangements, leading to a decrease of dipolar relaxation frequency (from 16 to 13.5 kHz) and an increase of the relaxation strength (around 20%). TSDC measurements have shown a current peak shift towards higher temperatures, and a significant intensity decrease, which is proportional to the quantity of released charges. 相似文献
105.
Yong Zhang 《Journal of Physics and Chemistry of Solids》2008,69(1):111-115
The role of next-nearest-neighbor hopping interaction in determining the band structures and lattice configurations of combined polarons in pernigraniline-base polymer is explored on the basis of the Baranowski-Büttner-Voit (BBV) model. Numerical calculations show that the valence band extends to a larger range while the conduction band acts to the contrary, as the strength of the next-nearest-neighbor hopping interaction increases. The width of the Peierls gap and the number of the bound states trapped in have almost no changes. If the coupling strength β<0.15, the transition energy from the lower gap level to the higher one for a combined electron-polaron matches the long-lived 1.5 eV photoinduced absorption peak [J.M. Leng, R.P. McCall, K.R. Cromack, Y. Sun, S.K. Manohar, A.G. MacDiarmid, A.J. Epstein, Phys. Rev. B 48 (1993) 15719], and also supports the high temperature dispersion in the thermally stimulated depolarization current (TSDC) experiment [A.N. Papathanassiou, J. Grammatikakis, S. Sakkopoulos, E. Vitoratos, E. Dalas, J. Phys. Chem. Solids 63 (2002) 1771]. For a combined hole-polaron, new shallow level emerges when β∼0.12. 相似文献
106.
A novel composite alkaline polymer electrolyte based on poly(vinyl alcohol) (PVA) polymer matrix, titanium dioxide (TiO2) ceramic fillers, KOH, and H2O was prepared by a solution casting method. The properties of PVA-TiO2-KOH alkaline polymer electrolyte films were studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and AC impedance techniques. DSC and XRD results showed that the domain of amorphous region in the PVA polymer matrix augmented when TiO2 filler was added. The SEM result showed that TiO2 particles dispersed into the PVA matrix although some TiO2 aggregates of several micrometers were formed. The alkaline polymer electrolyte showed excellent electrochemical properties. The room temperature (20 °C) ionic conductivity values of typical samples were between 0.102 and 0.171 S cm−1. The Zn-Ni secondary battery with the alkaline polymer electrolyte PVA-TiO2-KOH had excellent electrochemical property at the low charge-discharge rate. 相似文献
107.
108.
Material databases of plastics are becoming more and more the focus of applied science and commercial use in industry. Material properties of material manufacturers are often provided in publicly accessible material databases, which usually contain processing and mechanical properties under static loadings. Fatigue strength values are usually not accessible. The fatigue data for thermoplastics is of particular interest, as these materials have a particularly high lightweight construction potential and can be processed with a high degree of automation and reproducibility.Individual fatigue strength parameters for a specific material, environmental condition, geometry and loadings have been investigated in numerous publications. However, no work has been found in which fundamental interactions of different materials, environmental conditions, geometries and loadings on the course of the S/N-Curve have been investigated.In this paper, different effect relationships between temperature, filler type and filler content, fiber orientation and load ratio will be presented for the material Polypropylene (PP). A fatigue strength database of 11 different material manufacturers, from 71 different S/N-Curves with 606 tested samples, serves as a basis. The fatigue database enables a digital twin, which is used for the design of structural components to add a third dimension with artificial intelligence, and which is trained by an engineer. From the determined effect relationships, fatigue factors are to be derived and can be used to evaluate the fatigue strength of a component in the design process and to train the digital twin. The fatigue-strength values from the database also allow a statistical consideration of the slope k and the scattering of the S/N-Curve. The different S/N-Curves are transferred into a Haigh diagram, from which the functional course of the mean stress is determined. 相似文献
109.
110.
A modified silica nanoparticle (MSNP) solution was formed by the encapsulation of negatively charged silica nanoparticles by the UV-crosslinkable polycation oligomer diazo-resin (DAR). Appropriate DAR encapsulation concentrations were determined by use of zeta-potential and dynamic light scattering measurements. The MSNPs were used in conjunction with poly(styrene sulfonate) (PSS) to grow homogenous ionic self-assembled multilayer anti-reflection coatings. Stability was induced within the films by the exposure of UV-irradiation that allowed for crosslinking of the DAR and PSS. The films were characterized by UV/vis/IR spectroscopy and field emission scanning electron microscopy. The transmission and reflection levels were >98.5% and <0.05%, respectively. The refractive indices resided in the 1.25–1.26 range. The solvent stability was tested by sonication of the films in a ternary solvent (H2O/DMF/ZnCl2 3:5:2 w/w/w). 相似文献