Materials Science Forum Vols. 654-656

Abstract: Mesoporous carbon with MoO3 loading (MoO3/CMK-3) was obtained via ultrasonic assembly with CMK-3 as the host material and MoO3 as the guest material which was yield from MoO3ּpH2O2ּqH2O sol precursor. The microstructures of such MoO3/CMK-3 composites were characterized by X-ray diffraction (XRD), nitrogen adsorption and desorption, X-ray photoelectron spectra (XPS), Fourier-transform infrared (FTIR) and transmission electron microscopy (TEM). The results show that the method of ultrasonic assembly was efficient to highly disperse MoO3 nanoparticales into the channels of mesoporous carbon.

Abstract: In this paper, gelatin-arabic gum microcapsules containing Artemsia argyi oil was prepared by complex coacervation firstly, along with its application to textile finishing using 2D resin as a crosslinking reagent was investigated. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to investigate the formation of ether bonds between 2D resin and cellulose and/ or gelatin-arabic gum microcapsules. The washing durability, strength retention, wrinkle-free performance, formaldehyde content, release property and antibacterial property of the finished fabrics were also tested. The results showed that the crease recovery angle of finished fabric was above300°, with the strength retention was above 60% and the released formaldehyde concentration was lower than 75 mg/kg. While the released amount of Artemsia argyi oil was less than 50% after 9 days. Moreover more than 70% antibacterial property could also be obtained even after 30 washing cycles.

Abstract: Ethylene gas is released from plants as a hormone during a certain stage of life cycle and induces ripeness in fruits and blooming of flowers. The early detection and control amount of ethylene gas in storage can prevent wastage of the entire stock. The aims of this research were to fabricate ethylene sensor based on polyaniline (PANi) and to investigate the effect of acid doping on an improvement of its sensitivity. Electrochemically synthesized conductive layer of PANi was prepared via an in situ radical polymerization by repeating potential cycling in the range of -0.3 to 1.0 V relative to the silver reference electrode and platinum counter electrode. The PANi films were deposited on interdigitated electrode of gold substrate. These emeraldine bases of PANi were doped with five different acids doping (such as HCl, H2SO4, H3PO4, TSA, and DBSA) at particular concentration. The influences of types and amount of acid on the sensitivity of acid doping PANi on ethylene gas were investigated. The PANi-dope films were characterized by Fourier transform infrared spectroscopy (FT-IR) and UV-visible spectroscopy (UV-vis). The morphology of PANi film was investigated by scanning electron microscope (SEM). The magnitude sensing of doping PANi in terms of types and amount of acid against ethylene gas was presented. Introduction

Abstract: This research was a study of physical and mechanical properties of polyethylene foam incorporated with various amount of lignin from 5 to 20 phr.The lignin was isolated from black liquor from Kraft pulping using a sulfuric acid at pH 3 and washed with hot water. A Fourier Transform Infrared Spectroscopy (FTIR), Thermo Gravimetric Analyzer (TGA), and Laser Light Scattering were used to characterize the extracted lignin.The preparation of polyethylene foam was carried out using two-roll mill and compression moulding.Visual inspection, density measurement, and Scanning Electron Microscope (SEM) were used to investigate physical properties while compression test and compression set were used to investigate mechanical properties.The average lignin particle size diameter appears to be 31.733 m. The foam density increased slightly with amount of lignin.From SEM micrographs, it exhibited that all PE foams had a closed-cell structure where the cell sizes varied with amount of lignin.Foam incorporated with 10 phr of extracted lignin showed the finest cell distribution with an average cell diameter of 0.51 millimeters.

Abstract: Using our recently developed in situ transmission electron microscopy techniques, we revealed that the FCC structured Ni nanowires with diameter of about 30 nm possess ultra-large strain plasticity. Dynamic complex dislocation activities mediated the large strain bent-plasticity and they were monitored at atomic scale in real time. The bent-induced strain gradient allows studying the strain effects on dislocation mediated plasticity. We also explored the deformation techniques to more general cases, the nano thin films. An example of tensile Pt ultra-thin film is presented.

Abstract: Orientation-imaging microscopy offers unique capabilities to quantify the defects and damage evolution occurring in metals following dynamic and shock loading. Examples of the quantification of the types of deformation twins activated, volume fraction of twinning, and damage evolution as a function of shock loading in Ta are presented. Electron back-scatter diffraction (EBSD) examination of the damage evolution in sweeping-detonation-wave shock loading to study spallation in Cu is also presented.

Abstract: Recently, three-dimensional (3D) observation and analysis have attracted considerable attention in materials science field. By using the synchrotron radiation, the tomography makes possible high-resolution 3D observation dynamically and the recent diffraction analysis is available for 3D orientation mapping. In this study, grain deformation behavior in polycrystalline aluminum alloy has been characterized by 3D observation method applying the synchrotron radiation. The method to measure inner strain distribution by means of microstructural features tracking provides strain distribution within the sample, which we could not access before. The effect of grain orientation and its interaction during tensile deformation was discussed with the obtained strain distribution.

Abstract: Three-dimensional structure of crack tip dislocations were investigated by combining scanning transmission electron microscopy (STEM) and electron tomography (ET) in silicon single crystals. P-type (001) silicon single crystals were employed. <110> cracks were introduced from an indent on the (001) surface. The specimen was heated at 873K in order to introduce dislocations at the crack tips. The specimen was thinned to include the crack tip in the foil by an iron milling machine. STEM-ET observation revealed the three-dimensional structure of crack tip dislocations. Their Burgers vectors were determined by using an invisibility criterion. The local stress intensity factor was calculated using the dislocation characters obtained in the observation in this study, indicating that the dislocations observed were mode II shielding type dislocations.

Abstract: To apply nano-structured materials in micro/nano system, understanding of the mechanical properties of nano-structured materials is required. In order to perform the mechanical test of nano-structured materials, the mechanical testing system was installed in a scanning electron microscope (SEM). The nano-manipulator was set up in the SEM, and the force sensor formed as a cantilever was mounted on the nano-manipulator. Then, the force sensor can be controlled by using the nano-manipulator. The nano-structured materials were dispersed on the transmission electron microscope (TEM) grid, and both end of the nano-structured materials were welded on the TEM grid and the tip of force sensor by exposing E-beam of the SEM. The tensile tests for carbon nanotubes, ZnO nanorods and ZnS nanowires were carried out in the SEM, respectively. The load response during the mechanical test was obtained by force sensor. The dimension of nano-structured materials was obtained by determining the configuration measured from the TEM. And, strain-stress curve was obtained after mechanical test. The elastic modulus of the nano-structured materials after the tensile tests were calculated and compared. The elastic modulus for multi-walled carbon nanotubes, ZnO nanorod and ZnS nanowire were ~0.98 TPa, ~59 and ~39 GPa, respectively.

Abstract: The instrumented indentation test (IIT) is a mechanical testing method to determine the hardness and elastic modulus of materials by putting an indenter into a material surface. This technique has now gone beyond normal hardness tests by evaluating additional properties of materials and by allowing testing at much lower forces and indentation depths (micro/nano ranges). This study presents analytic models and procedures for evaluating tensile flow properties and residual stress state using IIT; the tensile flow properties are treated by defining a representative stress/strain beneath a spherical indenter and the residual stress by using a stress-insensitive contact hardness model. The IIT results are compared with those from conventional methods such as uniaxial tensile test and X-ray diffraction. In addition, IIT can be used as a multiscale mapping tool for the mechanical properties of composite materials and constituent phases by using macro/micro/nano indentation system: we made a hardness map of multiphase steel and measured the strength/residual stress distributions of welded pipeline.