Anca Dumitru

CsHSO4/Nanooxide Polymer Membranes for Fuel Cell

Composite solid acid/nanooxide polymer membranes with good electrical behaviour can be obtained by thermocentrifugal field processing. The supporting polymer matrix is designed to embed solid acids or strong solid acids/nanooxides making it appropriate for proton conducting composite membranes. Nanocomposites CsHSO4-YSZ/PAN membranes were investigated by Raman, FT-IR and SEM techniques. The dependence of the electrical conductivity on temperature is evaluated.

Silicon Dicarbide Synthesis

A method for the synthesis of the hypothetical silicon dicarbide structure is proposed. This structure with tetragonal symmetry has been synthesized in matrixes of hardened novolac with silicon powder. Thermal treatment up to 1200°C induces in these matrixes spiroconjugation features with subsequent organizing in tetragonal symmetry. XRD, HRTEM patterns and SAED confirmed that the hypothetical structures proposed are synthetically realizable.

Synthesis and Characterization of Carbon Supported Pd and PtPd Catalysts for DMFCs

Carbon supported Pd and PtPd catalysts were prepared by chemical reduction of metal precursors with sodium borohydride. Multi-wall carbon nanotubes (MWNTs) were used as carbon support. The composition of prepared catalysts was given by EDX technique. Cyclic voltammetry (CV) measurements were used to evaluate the electrocatalytic activities for methanol electrooxidation after their immobilization onto carbon paper.

Highly Oriented Carbon Ribbons for Advanced Multifunctional Material Engineering

Abstract Two classes of carbon fibers—one based on MP (Mesophase Pitch) precursors and another on PAN (Polyacrylonitrile) precursors—are well known. Thermomechanical properties depend strongly on the initial precursor, particularly PAN tacticity. Regular, highly oriented carbon fibers require a syndiotactic PAN that is virtually impossible to reach. To improve the attributes of these materials, a new technique was developed, consisting of the deposition of thin films in a high centrifugal field with simultaneous thermal treatment. This technique makes it possible to obtain carbon ribbons made up of well‐aligned micro‐ and nanocarbon fibers. Our first investigations, which were conducted with regular precursors for PAN‐fiber, using deposition in a centrifugal‐thermal field, showed good potential for carbon coating at different stages of carbonization. The centrifugal field and thermal treatment simultaneously applied induced transformations in preferential directions. PAN‐carbon ribbon (PAN‐CR) deposited onto A1‐foil at different stages of carbonization is characterized. The dependence of initial precursor and ribbon properties on molecular orientation (monitored by FT‐IR, XRD, Raman) is presented.

Plasma Polymerization of thin Films using Aniline and P-Xylene Precursors

Low dimensional polymer films were obtained by plasma polymerization of aniline and p-xylene onto silicon (111)/quartz glass substrates The reactions were conducted in a original designed RF reactor, inductively coupled with a 2 54 MHz generator, taking advantage of the electrodless configuration The structural characteristics observed by XRD, Raman and FT-IR spectroscopy were correlated with resistivity dependence measurements at moderated pressures Highly cross-linked plasma polymer films have a resistivity ranging from insulator to semiconductor FT-IR spectra show a number of quite broad single peaks indicating a range of closely related structures rather then one well-defined structural state