Applied Mechanics and Materials Vols. 633-634

Abstract: Different polyaniline micro/nanostructures were prepared in by oxidative polymerization doped with different acids like citric acid (C6H8O7), H₃PO₄ and HCl. The samples were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and UV–Visible spectral techniques. The rod-like composites, microspheres and nanofiber of polyaniline could be synthesized by different doting. The corrosion studies were carried out on steel plates coated with epoxy coatings containing polyaniline prepared with acid doping and no acid doing. Corrosion protection of these epoxy coatings containing prepared polyaniline (PANI) on steel was studied by Tafel polarization test in 3.5wt% sodium chloride (NaCl) aqueous solution. The results indicated that coatings prepared from acid doped polyaniline particles were found to exhibit excellent corrosion resistance much superior to no acid doped PANI in aggressive environments, and the epoxy coating containing PANI obtained in HCl doping had the best performance of the corrosion protection in all systems under investigation. The possible protective mechanism of PANI was discussed.

Abstract: Dielectric elastomer actuators (DEAs) represent one class of electroactive polymers that have already demonstrated excellent performances and show potential applications in many fields. In this paper, we present a simplified conically-shaped dielectric elastomer actuator model to explore the effects of various preloads and actuation voltages on both the actuation displacement and force output of DEA. The strain energy potential of Yeoh is used and the viscoelasticity is also taken into account. Using the developed model, the numerical results of DEA including the actuation displacement, the distribution of the principal stretch ratios and principal stresses in the membrane and the force output can be obtained. With different preloads and actuation voltages, the actuation characteristic of conically-shaped dielectric elastomer actuator is explored experimentally and validates the results determined from the proposed model. The proposed model can be used for the design and optimization of conically-shaped dielectric elastomer actuator.

Abstract: Biodegradable polyurethane foam (PUF) was prepared by using tung oil and starch as the modifiers, they were mixed with polyether polyol and some other reaction auxiliary agents, and then reacted with toluene diisocyanate (TDI). The structure and thermal stability of products were analyzed based on SEM and TG, and the soil burial method was used to investigate the biodegradability of products. The results indicated that polyurethane foam modified by tung oil and starch has good thermal stability, good mechanical properties and good biodegradability. The degradation rate of PUF modified by 5: 2 of starch/ tung oil was 38% after 120 d.

Abstract: Self-cleaning coatings are getting tremendous attention from both the academic interest and industrial communities. Among the two kinks of self-cleaning coatings, which are super-hydrophobic and super-hydrophilic coatings, the super-hydrophilic self-cleaning coating comprised of TiO₂/doped-TiO₂ has four unique features when exposed to ultraviolet (UV) light or sunlight, which are self-cleaning property, anti-bacterial properties, environmental friendly, and visible-light photocatalysts and indoor usage. And PU-TiO₂ self-cleaning coating produced by “grafting” method, which can accomplish stable chemical attachment between the nTiO₂ and the PU substrates, may potentially show an increase of the thermal properties, an increase of the amount of active sites for photo-catalysis, and a decrease in the self-degradation of the resulting polymer nanocomposite than the traditional mechanical shear method. There is a tremendous scope for the application of polyurethane-nTiO₂ self-cleaning coatings in industrial, health care and consumer sectors.

Abstract: Injection molded discontinuous fiber reinforced components are widely used in many demanding engineering applications and are exposed to a complex combination of thermo-mechanical loads. Mean field homogenization approach was successfully applied for predicting the global stiffness behavior over wide part geometry complexity, fiber orientation distribution (FOD) and loading situations including loading rate and temperature dependence. The prediction of the component strength, however, is significantly more complicated and requires additional and theoretical considerations as well as the application of various numerical tools and sophisticated experiments. To overcome above difficulties the MFH technique was extended with the first pseudo grain failure or damage (FPGF or FPGD) approach proposed by the research group of Doghri [1] elaborated in detail using short glass fiber reinforced PP-GF in the PhD Thesis of Reiter [2] and shortly described in this study.

Abstract: The compatibilities of polymer blends, Polypropylene (PP) and Polyamide12(PA12), was simulated by molecular dynamics (MD) simulations. Density, cohesive energy density (CED) ,and solubility parameters (δ) of pure substances and PP/PA12 blends were calculated by MD simulations with the COMPASS force field for the prediction of polymer blends compatibility . Results showed that PP/PA12 is not miscrible by comparing the difference in the solubility parameter value ( Δδ), radial distribution function value. The predictions agreed well with the experimental results. So it can be showed that MD simulation is a valid method to provide information on miscibility of polymer blends.

Abstract: HT300 (Cast Iron) is widely used in heavy machines, and the metal magnetic memory (MMM) technique can is used to evaluate early damage of the following metal while calculating the stress concentration. An experimental investigation of the effect of stress on permeability of HT300 has been undertaken on cast iron. The result showed that the stress can alter the permeability of the material which will amplify the magnetic field of the specimen. Further, simulation was used to evaluate the characteristics of magnetic signal under different conditions. The present work indicate that the MMM can detect stress concentration and early stage of damage effectively.

Abstract: The shape and stability of growth interface have significant influence on the floating zone (for short FZ) silicon crystal. During the growth of crystal cone, growth interface reversal will happen due to the change of cooling mechanism, which makes crystal growth unstable. This impact will be more obvious for crystal with large diameter. During the growth of crystal body, with the crystal diameter increasing, the growth interface curvature and thermal stress both increase, which is easy to result in dislocation and even crack of the crystal. So this experiment mainly studied how to solve the instability problem due to interface inversion and how to reduce interface curvature. In the experiment we compared the growth interface shape of 6 inches <111> FZ silicon, at different pull speed, and find that during the growth of crystal cone, interface inversion can finish ahead with higher pull speed, and during the growth of crystal body, interface curvature decreased (interface depth≈32 mm) with lower pull speed ( υ=2.5mm/min) and higher rotate speed, to increases the chances for success of crystal growth.

Abstract: The work introduces the spectra of fluorescent derivatives which have been annealed. It’s usually unstable when heated or electrified, showing the red-shift and emerging new emission peak. We analyze the connection between emission peak and temperature. OF3R4, OF3R6, OF4R4, which are characterized by NMR. By contract, different temperatures and materials have similar phenomenon.

Abstract: Co-doped rod-like ZnO particles with nominal Co doping concentration of 1 at% were synthesized by hydrothermal method and characterized by X-ray diffraction, field-emission scanning electron microscopy, photoluminescence and superconducting quantum interference device. The results show that the as-synthesized samples are pure hexagonal wurtzite structure without metallic Co or other secondary phases and display rod-like shape with smooth surface. The room temperature PL spectrum of the Co-doped rod-like ZnO particles exhibits a strong blue emission at 440 nm, a shoulder violet emission at 410 nm and a weak green emission centered at 550 nm. The magnetization measurements reveal that the Co-doped rod-like ZnO particles show ferromagnetic behavior at room temperature. The saturation magnetization and coercive field are 0.0125 emu/g and 45 Oe, respectively.