Advanced Engineering Materials

Cover image for Advanced Engineering Materials

September, 2004

Volume 6, Issue 9

Pages 701–787

    1. Contents: Adv. Eng. Mater. 9/2004 (pages 701–704)

      Article first published online: 8 SEP 2004 | DOI: 10.1002/adem.200490007

    2. Preparation and Application of Nanostructured Perovskite Phases (pages 709–714)

      A. Weidenkaff

      Article first published online: 8 SEP 2004 | DOI: 10.1002/adem.200400098

      Perovskite-type transition-metal oxide phases have attracted significant attention due to their useful physical and chemical properties. Thus, they are known to be suitable catalysts for different redox reactions in e.g. electrochemical applications resulting from the ability to respond reversibly to oxidising and reducing environment. For the development of novel functional materials the properties of these materials are tuned by compositional and morphological variations applying different chimie douce preparation methods.

    3. Hyperbranched Polymer/Clay Nanocomposites (pages 715–719)

      M. Rodlert, C.J.G. Plummer, H.J.M. Grünbauer and J.-A.E. Månson

      Article first published online: 8 SEP 2004 | DOI: 10.1002/adem.200400073

      Nanocomposites have been prepared from a range of hyperbranched polymers (HBPs) and montmorillonite clays (MMTs) by solution processing. With high levels of exfoliation significant changes in rheological behaviour were observed. Rheological models for conventional filled polymers led to estimates of the effective particle aspect ratio. In combination with classical models for particle reinforcement, the derived parameters accounted well for the evolution of the mechanical properties of solid HBP-based polyurethane nanocomposites.

    4. SU8-Silver Photosensitive Nanocomposite (pages 719–724)

      S. Jiguet, A. Bertsch, H. Hofmann and P. Renaud

      Article first published online: 8 SEP 2004 | DOI: 10.1002/adem.200400068

      A photosensitive composite resist having electrical properties has been developed for the direct photopatterning of electrically conductive microcomponents. This composite material is based on the dispersion of silver nanoparticles into the SU-8 photopolymer, an insulating negative-tone photoresist. Electrical and optical characterizations reveal a wide range of electrical conductivity of the composite structures depending of the filler load, and a lateral resolution better than 5 μm.

    5. Polyamide-6/Silica Nanocomposites (pages 724–729)

      M. García, J. García-Turiel, B. Norder, F. Chavez, B.J. Kooi, W.E. van Zyl, H. Verweij and D.H.A. Blank

      Article first published online: 8 SEP 2004 | DOI: 10.1002/adem.200400059

      New strategies were developed which incorporate silica nanoparticles (<30 nm) into a nylon-6 matrix, to form technically interesting hybrid nanocomposites with improved stiffness. Silica particles retained their original shape and size (10–30 nm), are mono-dispersed and mainly non-agglomerated as shown by TEM. Mechanical tests on the composites were conducted and showed that with less than 0.1 volume fraction of silica addition the E-modulus of the nanocomposite increased when compared with neat nylon-6. Furthermore, the rheological properties of the nanocomposites were determined. The viscosity showed a very dependant behavior at different filler loadings. The viscosity of highly filled samples was mainly caused by interactions between particles.

    6. Smart Nanostructured Polymeric Coatings for Use as Remote optical Strain Sensors (pages 729–733)

      J. Halary, P. Cookson, J.L. Stanford, P.A. Lovell and R.J. Young

      Article first published online: 8 SEP 2004 | DOI: 10.1002/adem.200400061

      This research study is aimed at developing a novel high-resolution non-contact stress/strain sensor system applicable for a wide variety of engineering components used in both laboratory and in-the-field (external) applications. Nanocomposites and nanostructured polymers with unique opto-mechanical properties were developed as smart coatings. Remote polarized Raman spectroscopy was used to monitor the strain sensitivity of deformed coatings, and determine local strains on the micron scale directly from stress/strain induced Raman band shifts.

    7. Processing of Transparent Conducting Coatings Made With Redispersible Crystalline Nanoparticles (pages 733–737)

      J. Puetz, N. Al-Dahoudi and M.A. Aegerter

      Article first published online: 8 SEP 2004 | DOI: 10.1002/adem.200400078

      The present paper describes recent developments in the employment of ITO (In2O3:Sn) nanoparticles for the preparation of transparent conducting coatings and discusses capabilities and limits of this approach, especially for applications in display and smart window technology. Meanwhile, redispersible nanoparticles of ITO, which shows the best electrical properties among the transparent coating oxides (TCOs), can be produced reproducibly on an industrial scale and various products are on the market.

    8. Preparation and Characterization of Styrene Butadiene Rubber Based Nanocomposites and Study of their Mechanical Properties (pages 738–742)

      S. Sadhu and A.K. Bhowmick

      Article first published online: 8 SEP 2004 | DOI: 10.1002/adem.200400066

      Nanocomposites were prepared from styrene butadiene rubber (SBR) having different styrene contents and octadecyl amine modified Na-montmorillonite clay (OC). The modified and the unmodified clays were characterized with the help of X-ray diffraction technique (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Transmission Electron Microscopy (TEM). All these nanocomposites were then subjected to tensile testing. The modified clay-rubber nanocomposites showed improved tensile strength (55% increase) and elongation at break (76% increase) compared to those of the gum vulcanizates.

    9. Reversible Tenso-Resistance and Piezo-Resistance Effects in Conductive Polymer-Carbon Nanocomposites (pages 742–746)

      M. Knite, V. Teteris, A. Kiploka and I. Klemenoks

      Article first published online: 8 SEP 2004 | DOI: 10.1002/adem.200400062

      Recently efforts have been made to obtain active polymer-elektrically conductive particle composites the conductivity of which would be strongly dependent on external thermodynamic parameters – pressure, temperature, and other. New interesting properties are expected in case the polymer composite contains dispersed nano-size conducting particles. The present study is focused on examining electrical resistance vs tensile strain and pressure of polyisoprene-corbon nanocomposites near the percolation threshold to find the best composition for sensor applications.

    10. Alternating-Current Properties of Elastomer-Carbon Nanocomposites (pages 746–749)

      M. Knite, V. Teteris, I. Aulika, H. Kabelka and A. Fuith

      Article first published online: 8 SEP 2004 | DOI: 10.1002/adem.200400063

      Analysis of conductivity and dielectric permittivity as functions of applied AC frequency and features responsible for the giant tenso-resistance effect in polyisoprene-extraconductive carbon black nanoparticles composites are presently reported. The experimentally obtained results are in good agreement with the mechanism of inter-cluster polarisation. Some deviation from the statistical percolation theory at carbon concentrations above the percolation threshold is discussed.

    11. Chemical and Thermal Stability of Alkylsilane Based Coatings for Membrane Emulsification (pages 749–754)

      M.J. Geerken, T.S. van Zanten, R.G.H. Lammertink, Z. Borneman, W. Nijdam, C.J.M. van Rijn and M. Wessling

      Article first published online: 8 SEP 2004 | DOI: 10.1002/adem.200400060

      Silicon nitride microsieves are excellent candidates for their use in membrane emulsification processes. These microsieves have well-defined pores with extremely narrow pore size distributions. To produce water in oil emulsions the surface of the microsieves has to be altered from a hydrophilic to a hydrophobic state. We establish this by applying a coating based on self-assembled monolayers of alkylchlorosilanes. This paper focuses on the chemical and thermal stability of these coatings considering the cleaning procedures used in food and diary industry.

    12. Cellulose Fibrils for Polymer Reinforcement (pages 754–761)

      T. Zimmermann, E. Pöhler and T. Geiger

      Article first published online: 8 SEP 2004 | DOI: 10.1002/adem.200400097

      Agglomerated cellulose fibrils embedded in a lignin matrix in the cell wall are a predominant reason for the outstanding specific tensile strength of wood. To convert these mechanical properties to practical use for polymer composites, the fibrils were isolated out of sulphite pulp. Depending on the disintegration method, the fibrils have diameters in the nanometer and lengths in the micrometer range.

    13. Cutting of SiC Fibers for Ti-MMC Applications (pages 761–767)

      M. Herkt, F. Heutling and U. Koch

      Article first published online: 8 SEP 2004 | DOI: 10.1002/adem.200400101

      This study compares different methods to cut SiC fibers as a semi-finished product for the production of lightweight Ti-MMC parts with high specific strength and stiffness for aerospace applications. Special attention has to be paid to the cutting surface morphology of fibers to get a homogeneous distribution of fibers in the final part. As a test, Titanium 6–4 coated and uncoated SiC fiber types have been cut with three different methods: bending, cutting the fibers with scissors, laser cutting.

    14. Processing and Characterization of Al-Cu and Al-Mg Base Composites Reinforced with TiC (pages 767–775)

      A. Contreras, A. Albiter, E. Bedolla and R. Pérez

      Article first published online: 8 SEP 2004 | DOI: 10.1002/adem.200400102

      Most of the work on metal matrix composites (MMCs) is based in Al and its alloys, because of its high electrical conductivity, heat treatment capability and low density. The current study presents the infiltration behavior of liquid Al-Cu and Al-Mg alloys into TiC preforms. Some mechanical and microstructural properties of the infiltrated composites are also presented, in addition to transmission electron microscopy studies (TEM).

    15. Properties of ZrB2-Reinforced Ternary Composites (pages 775–781)

      D. Sciti, C. Melandri and A. Bellosi

      Article first published online: 8 SEP 2004 | DOI: 10.1002/adem.200400039

      Different amounts of ZrB2 particles are added to a matrix constituted by AlN+SiC for the production of novel electro-conductive composites by hot pressing. The presence of ZrB2 particles makes the composites electro-conductive and improves many relevant mechanical properties, such as toughness, hardness and strength. The new materials can reach a fracture toughness of 4 MPa.m1/2 and strength of 504 MPa at 1400°C.

    16. Enhanced Strength and Ductility in Ultrafine-Grained Aluminium Produced by Accumulative Roll Bonding (pages 781–784)

      H.W. Höppel, J. May and M. Göken

      Article first published online: 8 SEP 2004 | DOI: 10.1002/adem.200306582

      Due to a printing error in the Adv. Eng. Mater. 2004, 6, issue 4, this article, originally published on pages 219–222, had to be reprinted. Now the correct references are given to allow all readers the correct access to the literature. The editorial team apologizes for any inconveniences this may have caused.

    17. High precision densitometry of small specimen (pages 784–786)

      M. Sonnleitner and R. Danzer

      Article first published online: 8 SEP 2004 | DOI: 10.1002/adem.200406031