Material innovation institute

Delft, Netherlands

Material innovation institute

Delft, Netherlands
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Chen X.,Technical University of Delft | Chen X.,Guilin University of Electronic Technology | Yuan C.A.,Technical University of Delft | Yuan C.A.,TNO | And 6 more authors.
Sensors and Actuators, B: Chemical | Year: 2012

We proposed a molecular modeling methodology to study the protonic acid doping of emeraldine base polyaniline which can used in gas detection. The commercial forcefield COMPASS was used for the polymer and protonic acid molecules. The molecular model, which is capable of representing the polyaniline doping with the aqueous hydrochloric acid, was built by Monte Carlo method. The initial entire systems were equilibrated using a new protocol, which aims at creating a final structure with realistic density and low-potential energy characteristics. The doping process is modeled by a combined molecular mechanics and molecular dynamics simulation techniques. The radial distribution functions of doped emeraldine salt and the relationships including pK a/pH and doping percentage/pH, were computed and compared with the experimental data. This method contributes a novel molecular modeling approach to select and evaluate the conducting polymers in chemical sensor applications. © 2012 Elsevier B.V.


Van Soestbergen M.,Material Innovation Institute | Van Soestbergen M.,TU Eindhoven | Baukh V.,TU Eindhoven | Erich S.J.F.,TU Eindhoven | And 4 more authors.
Progress in Organic Coatings | Year: 2014

Carcinogenic chromates are phased out as corrosion inhibitors in organic coatings, and are replaced by benign alternatives. Cerium-based compounds are excellent corrosion inhibitors in an aqueous environment. However, whether they are effective as corrosion inhibitor in an organic coating also depends on their interaction with the coating matrix, which should result in a sufficient release of inhibitors over a desired period of time. In this work we report on the leaching of cerium dibutylphosphate, Ce(dbp)3, from an epoxy coating system as a first step toward a fundamental understanding of the leaching behavior. To this end, coating systems containing various levels of inhibitor loading, ranging from 1 up to 50 wt%, were fabricated. These coatings were characterized using Fourier transform spectroscopy (FTIR), and Scanning Electron Microscopy (SEM). Leaching experiments were performed by exposing the coating films to water, while the concentration of dissolved Ce(dbp)3 in this water was monitored in situ using ultraviolet-visible (UV-vis) spectroscopy. The leaching of inhibitors showed a clear dependence on the initial inhibitor loading of the coating system. For highly loaded coatings (>25 wt%) all inhibitors leach out, whereas for a low loading level (<10 wt%) no leaching was observed. The difference between the high and low loading levels might be the formation of a porous network in the highly loaded coatings due to the dissolution of large Ce(dbp)3 clusters. Using Magnetic Resonance Imaging (MRI) we visualized the penetration of a water front into this porous network during the leaching experiments. This water-filled porous network provides an excellent pathway for transport of Ce(dbp)3. For low levels of inhibitor loadings such a network is absent, and the transport of Ce(dbp)3 is blocked. The samples containing moderate levels of inhibitor loading showed an increasing amount of leaching for decreasing values of pH. We believe that this pH dependence is the result of the concurrent leaching of significant amounts of Bisphenol-based coatings residues at low pH since the removal of these residues will also result in an increased porosity of the coating. © 2014 Elsevier B.V.


Chen X.P.,Technical University of Delft | Chen X.P.,Guilin University of Electronic Technology | Yuan C.A.,Technical University of Delft | Yuan C.A.,TNO | And 6 more authors.
Molecular Simulation | Year: 2011

We report a molecular modelling study to validate the forcefields [condensed-phase optimised molecular potentials for atomistic simulation studies (COMPASS) and polymer-consistent forcefield (PCFF)] in predicting the physical and thermophysical properties of polymers. This work comprises of two key steps: (1) generating and validating the molecular model in predicting the material properties of the bulk amorphous emeraldine base polyaniline and (2) modelling the glass-rubber transition of the polymer. From all the molecular dynamics simulation results, it clearly shows that the more recent COMPASS forcefield provides a higher accuracy in predicting the polymer properties than PCFF, and it enables a more accurate prediction of condensed-phase properties (density, glass transition temperature, solubility parameters, etc.) in a broad range of temperature for various applications. © 2011 Taylor & Francis.


Krkoska M.,Material Innovation Institute | Barter S.A.,Defence Science and Technology Organisation, Australia | Alderliesten R.C.,Technical University of Delft | White P.,Defence Science and Technology Organisation, Australia | Benedictus R.,Technical University of Delft
Engineering Fracture Mechanics | Year: 2010

It is well known that variable amplitude fatigue loading produces progression marks on fatigue crack surfaces that are related to the loading sequence. These marks are generally a local change in the crack path. The same pattern of loading can produce a pattern of progression marks that have differences from material-to-material or from heat treatment-to-heat treatment, yet the crack path changes that produce these markings are not considered in the prediction of the crack growth behaviour. These path changes can be used to: investigate how the crack grows, aid crack growth measurement and shed light on the mechanism that forms striations. Consequently, an understanding of these path changes and their fundamental cause in structurally significant alloys is important to the explanation of how fatigue cracks grow and how their life can be predicted. In this paper, a number of simple loading sequences were used to investigate the influence that underloads have on the crack path, to develop a better understanding of the formation of fatigue striations and the coarser crack path changes associated with loading changes. The material chosen was aluminium alloy (AA)2024-T3. The results from the tests reported here were compared to previously investigated AA7050-T7451 specimens that were loaded in a similar manner. It is shown that the fatigue crack surfaces that were produced here were the direct consequence of the applied loading interacting with the crystal structure of the material. By changing the loading, via the addition of underloads it was possible to produce fatigue crack surfaces that where composed of not only striations but ridges, depressions and fissures. These features give an indication of the crack growth mechanism. Although, AA2024-T3 and AA7050-T7451 have different chemical compositions, mechanical properties and micro-structures, it was shown that both materials share essentially similar fracture features corresponding to crack propagation at the cycle-by-cycle level. It also appears that despite the above noted differences, similar failure mechanisms may take place. © 2010 Elsevier Ltd.


Sha W.,Queen's University of Belfast | Wu X.,Material innovation institute | Sarililah W.,Queen's University of Belfast
Materials Science and Engineering B: Solid-State Materials for Advanced Technology | Year: 2010

This paper follows previous X-ray diffraction work on crystallisation and phase transformation of electroless nickel-phosphorus deposits, concentrating on microstructural changes. Amorphous or nanocrystalline coatings, depending on their phosphorus content, were heat treated at temperatures between 100 and 500 °C for 1 h. Changes in microstructure after the heat treatment were examined using high-resolution field emission scanning electron microscope. Crystallisation and grain growth effects are observed, as well as some inherent defect structures in the coatings and their changes. These are compared with the previous X-ray diffraction work and in general, good agreement is observed. The complementary strength and weakness of the different characterisation techniques are discussed. © 2009 Elsevier B.V. All rights reserved.


Lafont U.,Material Innovation Institute | Lafont U.,Technical University of Delft | Moreno-Belle C.,Technical University of Delft | Van Zeijl H.,Technical University of Delft | Van Der Zwaag S.,Technical University of Delft
8th Asian-Australasian Conference on Composite Materials 2012, ACCM 2012 - Composites: Enabling Tomorrow's Industry Today | Year: 2012

Thermally conductive composite with a thermally triggered self-healing response were produced dispersing BN or Graphite particles into 2 type of polysulfide based thermoset matrix. The composites produced exhibit recovery of both cohesion and adhesion properties upon healing. Using a mild healing temperature (65 °C), the materials show full recovery of their initial adhesive strength during several healing cycles. In contrast the composites behave differently regarding the cohesion recovery: 100 to 20% recovery is achieved depending on the filler type, filler loading and the type of matrix. The thermal conductivity of the produced materials increase with the amount of filler. Valuesof 1 and 2 W/mK can be achieved for the BN and graphite based composite, respectively. The results presented in this work clearly show that multifunctional thermal interface materials with different functionality and self-healing response can be realised. Copyright © (2012) Asian-Australasian Association for Composite Materials (AACM).


Pan Y.,Material Innovation Institute | Richardson I.M.,Material Innovation Institute | Richardson I.M.,Technical University of Delft
Journal of Physics D: Applied Physics | Year: 2011

The production of consistent, high-quality laser welds on zinc-coated steels for the automotive industry remains a challenge. A simple overlap joint geometry is desirable in these applications but has been shown to be extremely detrimental to laser welding because the zinc vapour formed at the interface between the two sheets expands into the keyhole and disrupts fluid flow in the melt pool, which often leads to metal ejection. In this work, laser welding on sheets with various coating thicknesses has been performed and it is observed that the sheets with thick coatings (~20 μm) show surprisingly good weldability. High speed video camera visualizations of the keyhole provide insight into the keyhole dynamics during the process. It appears that the dynamic pressure of zinc vapour can effectively elongate the keyhole and the process can reach a stable state when an elongated keyhole is continuously present. A simple analytical model has been developed to describe the influence of zinc vapour on keyhole elongation. © 2011 IOP Publishing Ltd.


Alderliesten R.C.,Technical University of Delft | Schijve J.,Technical University of Delft | Krkoska M.,Material Innovation Institute
Fatigue of Materials II: Advances and Emergences in Understanding, Held During Materials Science and Technology 2012, MS and T 2012 | Year: 2013

Special load histories are adopted to obtain information about the behavior of the moving crack tip during the increasing and decreasing part of a load cycle. It is associated with the crack opening and closure of the crack tip. Secondly, modern SEM techniques are applied for observations on the morphology of the fractures surfaces of a fatigue crack. Information about the cross section profiles of striations are obtained. Corresponding locations of the upper and the lower fracture surface are also explored in view of the crack extension mechanism. Most experiments are carried out on sheet specimens of aluminum alloys 2024-T3, but 7050-T7451 specimens are also tested in view of a different ductility of the two alloys.


Lafont U.,Material Innovation Institute | Lafont U.,Technical University of Delft | Van Zeijl H.,Technical University of Delft | Van Der Zwaag S.,Technical University of Delft
ACS Applied Materials and Interfaces | Year: 2012

Synthetic systems with intrinsic self-repairing or self-healing abilities have emerged during the past decade. In this work, the influence of the cross-linker and chain rigidity on the healing ability of thermoset rubbers containing disulfide bonds have been investigated. The produced materials exhibit adhesive and cohesive self-healing properties. The recovery of these two functionalities upon the thermally triggered healing events has shown to be highly dependent on the network cross-link density and chain rigidity. As a result, depending on the rubber thermoset intrinsic physical properties, the thermal mending leading to full cohesive recovery can be achieved in 20-300 min at a modest healing temperature of 65 °C. The adhesive strength ranges from 0.2 to 0.5 MPa and is fully recovered even after multiple failure events. © 2012 American Chemical Society.


PubMed | Material Innovation Institute
Type: Journal Article | Journal: ACS applied materials & interfaces | Year: 2012

Synthetic systems with intrinsic self-repairing or self-healing abilities have emerged during the past decade. In this work, the influence of the cross-linker and chain rigidity on the healing ability of thermoset rubbers containing disulfide bonds have been investigated. The produced materials exhibit adhesive and cohesive self-healing properties. The recovery of these two functionalities upon the thermally triggered healing events has shown to be highly dependent on the network cross-link density and chain rigidity. As a result, depending on the rubber thermoset intrinsic physical properties, the thermal mending leading to full cohesive recovery can be achieved in 20-300 min at a modest healing temperature of 65 C. The adhesive strength ranges from 0.2 to 0.5 MPa and is fully recovered even after multiple failure events.

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