douniazad mezdour - Academia.edu (original) (raw)

Uploads

Papers by douniazad mezdour

Applied Surface Science, Nov 1, 2019

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Université de Jijel, 2017

AIP Conference Proceedings, 2019

This paper reports on the synthesis and physical properties of conducting composites based on pol... more This paper reports on the synthesis and physical properties of conducting composites based on polyaniline and polystyrene. Polyaniline composite powders are synthesized by oxidative polymerization in an acidic medium. Thermal properties are characterized by thermo gravimetric analysis and differential scanning calorimetry. UV-Visible absorption spectroscopy is also used to study the optical properties of the deposited films. The optical gap decreases from 4.6 eV to 2.7 eV with increasing polyaniline content from 0.5 to 5 wt. % confirming the improvement of the semi-conductive properties. Due to the absorption properties in near infrared of the thin composite layers they can be promising materials for optoelectronic and photovoltaic applications.

Spectroscopy Letters, 2017

This study presents a comparison of dielectric properties of composite materials consisting of in... more This study presents a comparison of dielectric properties of composite materials consisting of insulating polymers (Polyamides 6 and 12) containing polyaniline as a conductive phase. Samples were obtained by in situ polymerization of the aniline monomer in the presence of the insulating matrices. The results obtained by dielectric relaxation spectroscopy showed that it was possible to increase the permittivity of the samples by increasing polyaniline content. Polyamide12 based films exhibit high dielectric permittivities above percolation threshold. Polyaniline also induces relaxation phenomena, clearly visible at low temperature. It was also shown that dielectric relaxation phenomena are thermally activated. Some relaxations seem to be of the same nature in polyamide 6 and 12 films because they require nearly the same activation energy.

AIP Conference Proceedings, 2008

Percolation concept has been used in this study to estimate the amount of conductive fibers embed... more Percolation concept has been used in this study to estimate the amount of conductive fibers embedded in polymeric matrix, necessary to establish conduction in this kind of composites. The resistance of composite materials is calculated by simulating composite samples with different size, containing conductive fibers with various lengths Calculation is based on detecting conductive pathways through the insulating matrix, these pathways are assumed to be resistances in parallel. Electrical resistance curves showed a percolative behavior of the samples versus volume fraction of filler. Lower conduction thresholds are obtained for fiber aspect ratio of 20 and sample size of 100. The electrical resistivity and the conduction thresholds of the carbon fiber reinforced polycarbonate composites have been characterized. Simulation results are in good agreement with an experimental result found in the literature.

2014 North African Workshop on Dielectic Materials for Photovoltaic Systems (NAWDMPV), 2014

The present work deals with the preparation of films from polymeric core-shell particles. Our app... more The present work deals with the preparation of films from polymeric core-shell particles. Our approach is based on the chemical polymerization of a very thin layer of polyaniline (PANI) around particles of transparent polymers (polyamide and polystyrene). Films are then obtained by dissolving the two type synthesized core-shell powders in dichloromethane and m-Cresol respectively. Electrical properties were investigated using a dielectric relaxation spectrometer. Both composite films exhibited a percolative behaviour and a well established dc conductivity for high PANI concentration related to the conductive properties of the PANI spanning clusters. This property allows using such films in semi-conductive applications. For polyamide films, high dielectric constants were obtained at 5 wt. % of PANI allowing their use as high k-dielectrics compatibles with organic printed circuit boards.

The International Journal of Multiphysics, 2010

Three-dimensional simulations have been conducted to predict the percolation threshold in fiber c... more Three-dimensional simulations have been conducted to predict the percolation threshold in fiber composite materials. It has been shown that the expansion of the sample's size increases the sharpness of distributions curves of the percolation threshold. Decreasing the percolation threshold with longer fiber is also verified. A method is proposed to evaluate the electrical resistance of fibrous composites. Assuming meandering paths, the calculation is based on detecting conductive pathways through the insulating matrix. The percolation is detected by the height of the conducting cluster instead of its number at the two electrodes. The electrical resistivities and the conduction thresholds of the carbon fiber reinforced polycarbonate composites have been characterized. The simulation results are in good agreement with an experimental study result found in the literature.

ABSTRACT The present work deals with the preparation of transparent antistatic films from an extr... more ABSTRACT The present work deals with the preparation of transparent antistatic films from an extreme dilution of an intrinsically conducting polymer (ICP) with not coloured polymers. Our approach is based on the chemical polymerization of a very thin layer of Polyaniline (PANI) around particles of an insulating polymer (PA12). Films were obtained by dissolving the synthesized core-shell particles in m-Cresol. The electric property and structure relationships were investigated by using dielectric relaxation spectroscopy, X-ray diffraction and micro-Raman spectroscopy. Composite films exhibited a well established dc conductivity over all the frequency range for 10 wt. % of PANI concentration related to the conductive properties of the PANI clusters. X-ray diffraction data show broader and lower intensity of PA12 peaks when increasing PANI content, probably due to the additional doping effect of m-cresol. The doping of PA12/PANI films with Dodecyl benzene sulfonic acid (DBSA) was unequivocally verified by Raman spectroscopy.

physica status solidi c, 2011

Surface conductive composites for antistatic purposes consisting of polyamide 6 (PA‐6) polymer fi... more Surface conductive composites for antistatic purposes consisting of polyamide 6 (PA‐6) polymer films as a matrix containing conductive polyaniline (PANI) particles were chemically elaborated at room temperature by in situ polymerization of aniline inside the matrix. These kind of Polyamide/PANI composites were investigated regarding to their microstuctural and electrical properties. The surface conductivity was characterized using the potential decay technique. The results were correlated with scanning electron microscopic images data concerning PANI particles dispersion in these antistatic polymer films (ASPF). The enhanced surface conductivity was due to percolation of the PANI phase in the surface layer of PA‐6 films. It has been shown by X ray spectra that the crystallinity of the films is also enhanced. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Journal of Physics: Conference Series, 2009

Surface conductive composites consisting of polyamide 6 (PA-6) polymer films and conductive polya... more Surface conductive composites consisting of polyamide 6 (PA-6) polymer films and conductive polyaniline (PANI) particles were chemically elaborated by in situ polymerization of aniline inside the PA-6 matrix, at room temperature. The obtained composites were investigated regarding to their electrical properties. We have measured the frequency dependence of permittivity of these antistatic polymer films (ASPF). Surface conductivity was also characterized using potential decay technique. The enhanced surface conductivity was due to percolation of PANI phase in the surface layer of PA-6 films.

Macromolecular Symposia, 2010

Summary: Volume conducting PA‐12 based composites powders were chemically prepared by in situ pol... more Summary: Volume conducting PA‐12 based composites powders were chemically prepared by in situ polymerization and aniline doping at room temperature. These kinds of polyamide / PANI composites were investigated regarding their electrical properties. Their ac and dc electrical properties measured in the frequency range of 10−2–107 Hz are reported and the frequency dependence of electrical conductivity was investigated as a function of PANI concentration leading to the determination of the conductivity. The experimental conductivity was found to increase continuously with PANI content and explained by percolation theory with a relatively low percolation threshold of about 0.4 wt.%. The dielectric behavior of various PANI polymer composites has been characterized by the critical frequency ωc (denoting the crossover from the dc plateau of the conductivity to its frequency dependent ac behaviour). Modelling the conductivity behavior versus volume fraction using Slupkowski approach has rev...