The related articles of these works are available in the bibliography tab.
Postdoctoral training in Nancy (France): Nanostructures and ferroelectric nanocomposites: Synthesis, caracterisation, applications
Abstract: The aim of this project is to develop new nanocomposite materials with piezo and ferroelectric properties, and with various mechanical properties and shapes. The piezoelectric nanocrystal is the lithium niobate, which has never been synthesized as a nanofiller with a controlled size. The lithium niobate is piezoelectric in his mono-crystal form. It will be dispersed in various polymers, such as epoxy-amine systems or PVDF (in order to increase its piezoelectric properties). Then, the formed nanocomposite will be sudied by dielectric and brillouin spectroscopy and used to make Surface Acoustic Waves devices (SAW), as a collaboration with the LPMIA lab (SAW and piezoelectric materials specialist) takes place in Nancy.
Postdoctoral training in Saarbrücken (Germany): Study of DGEBA Prepolymer and Epoxy Network by DES.
Abstract: Dielectric spectroscopy is an extremely effective method for characterizing the molecular dynamics over a large range of time scales. Even if the ceramics are not well-known to be studied by dielectric spectroscopy, their dielectric behaviour makes them interesting as dielectric spectroscopy media. The mechanisms of polarization are the same than in polymers or other materials. Then we interested in the fitting programs. All of them are able to fit curves, and use the least squares method. These programs penalty are:
- Using the least squares approximation
- They do not take in account the error of the measurement
- The number of relaxation has to be fixed (and well-known)
- The fit need initial values
- Finally, the results can not be verified (problem of local minimum...)
- The parameter answer is given as an interval
- SADE does not need initial values
- It takes in account the error of measurement
- SADE used with Debye relaxations has a "real physical meaning"
- The best advantage is the given empty result if the supposed relaxation number is wrong, that means that SADE is able to determine the number of relaxation
PhD Thesis: Physico-chemical characterization of epoxy-amine / metal interphases, characterization of their constituentsDownload in PDF.
Slides used during the defense (Pdf).
Abstract: Epoxy-diamines are used as adhesives or paints in many industrial applications. When they were applied on metallic substrates and cured, an interphase, having chemical, physical, and mechanical specified properties, was created between the substrate and the polymer. The amine dissolved the hydrated metallic oxide layer and, at the same time, chemisorbed on the metal. The amine chemically reacted to form an organometallic complex. Then, complexes reacted with the epoxy monomer to form a new network. When over the complexes solubility limit, the chelates crystallized. Such crystals acted as short fibers, changing the mechanical properties of the coatings. Therefore, the different chemical, physical, and mechanical properties of these systems were determined and correlated to the formation and/or precipitation of the chelates. This occurred using two amines: the isophorone diamine, which crystallized after the reaction onto metal, and the diethylenetriamine, which never crystallized.
Last update : June 2012