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Zhang M.,Xidian University | Yuan Z.,Xian Jiaotong University | Ning T.,Construction Engineering Research Institute | Song J.,Xian Jiaotong University | Zheng C.,Xian Jiaotong University
Sensors and Actuators, B: Chemical | Year: 2013

Platinum is widely used to modify TiO2 based gas sensing materials, and the promotion mechanism accompanied by praiseworthy results are discussed deeply. In this work, the growth mechanism of Pt dispersed on TiO 2 thick film surface is discussed. The surface state of Pt is studied by XRD, XPS, SEM and Kröger-Vink defect theory in depth. Results indicate that Pt is not only dispersed on TiO2 thick film surface in metallic state but also occupy the lattice of Ti vacancy and form the oxidation state Ti1-xPtxO2. A simple model is proposed to explain the growth process of Pt and Ti1-xPtxO 2. © 2012 Elsevier B.V. All rights reserved.

Zhang M.,Xidian University | Ning T.,Construction Engineering Research Institute | Zhang S.,Xidian University | Li Z.,Xidian University | And 2 more authors.
Materials Science in Semiconductor Processing | Year: 2014

In this work, gas response properties of Pd modified TiO2 sensing films are discussed when exposed to H2 and O2. TiO2 films are surface modified in PdCl2-containing solution by the dipping method and treated for different treatment times to get different surface states. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and Kröger-Vink defect theory are used to characterize the sensing films. The gas response properties indicate that the sensor response time which related to the rate of change of sensor resistance is affected by the activation energy (E). In particular, the sensor treated at 900 C for 2 h exhibits a response time of about 20-240 ms when exposed to H2 and 40-130 ms when exposed to O2 at 500-800 C. © 2013 Elsevier Ltd.All rights reserved.

Li Y.,Xian Jiaotong University | Zheng J.-L.,Construction Engineering Research Institute | Feng J.,Xian Jiaotong University | Jing X.-L.,Xian Jiaotong University
Chemical Papers | Year: 2013

This article provides a brief overview of recent work by the authors' group as well as related researches reported by others on controlling the morphology and exploring the formation mechanism of typical micro-/nanostructures of polyaniline (PANI) and aniline oligomers through template-free aniline chemical oxidation process. The contents are organised as follows: (i) tuning the morphology of aniline polymerisation products by employing ultrasonic irradiation, mass transfer, and pH profiles; (ii) exploring the formation mechanism of micro-/nanostructures during aniline chemical oxidation through examining the precipitation behaviours of aniline oligomers and polymers in a post-synthetic system; (iii) tailoring PANI micro-/nanostuctures into pre-designed morphology by introducing certain heterogeneous nucleation centres; (iv) application potential of PANI nanofibres in the areas of transparent conductive film, electromagnetic interference-shielding coating and graphene-based electrode materials. This short review concludes with our perspectives on the challenges faced in gaining the exact formation mechanism of PANI micro-/nanostructures and the future research possibility for morphologically precisely controlled PANI micro-/nanostructures. © 2013 Institute of Chemistry, Slovak Academy of Sciences.

Zhao W.,Northwestern Polytechnical University | Liu W.L.,Northwestern Polytechnical University | Wang J.L.,Construction Engineering Research Institute
Applied Mechanics and Materials | Year: 2013

Several polymer-based drug delivery systems are being developed to enhance the extremely low water-solubility of paclitaxel (PTX). It is believed that there is a positive correlation between the compatibility of polymer-drug and the solubilization. In recent years, solubility parameters for polymer and drug were used to evaluate degree of compatibility between a drug and a polymer, which were measured using various experimental methods or estimated using the group contribution menthod (GCM). In this study, degree of compatibility between PTX and polymers were estimated by molar free energy of mixing (ΔGmix) that was calculated through computer simulation. It is found that the degree of compatibility is: PTX-PTRP > PTX-PLBG > PTX-PLGA > PTX-PCL > PTX-PLA. It has been demonstrated that the result of this study is in accord with the Similar Dissolve Mutually Theory. © (2013) Trans Tech Publications, Switzerland.

Wang J.,Construction Engineering Research Institute | Wu Y.,PLA Fourth Military Medical University
Journal of Elastomers and Plastics | Year: 2014

Styrene-butadiene rubber (SBR) was reinforced with silica (SiO2) by co-coagulating process. This study investigated the SiO2 amount, stirring time and pH value affecting the SiO2 content, curing characteristics and mechanical properties of SBR. Results showed that SiO2 content and reinforcing behavior were greatly influenced by the amount of SiO2 and pH value. The torque, tensile strength and elongation at break were optimal when the mass fraction of SiO2 was 21.5 wt%, stirring time was 6 h and pH value was 6.57. The utilized efficiency of SiO2 decreased with the increasing amount of SiO2 but increased with the increasing stirring time. The optimum cure time decreased with the increasing amount of SiO2. Both tensile strength and elongation at break decreased with the increasing pH value. Scanning electron microscopy observations showed that the SiO2 nanoparticles were distributed evenly in the SBR. © The Author(s) 2012.

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