Keywords : properties


Lamellar structures from graphene nanoparticles produced by anode oxidation

Mykola Kartel; Yuriy Sementsov; Galyna Dovbeshko; Liudmyla Karachevtseva; Stanislav Makhno; Tatiana Aleksyeyeva; Yulia Grebel

Advanced Materials Letters, 2017, Volume 8, Issue 3, Pages 212-216
DOI: 10.5185/amlett.2017.1428

An effective cheap method for graphene nanoparticles (GNP) production with controlled size distribution was developed based on anodic oxidation of condensed exfoliated graphite. As it is shown, under certain condition the GNP could be self-organized into a 3-dimensional structure that could be important for understanding of the GNP interaction with different type of surfaces. Based on this feature, a synthesis method for preparation of composites containing GNP and polychlorotrifluoroethylene (PCTFE) was developed. Raman spectroscopy of GNP and GNP/PCTFE revealed a good crystalline structure of synthesized nanoparticles. Laser correlation spectroscopy and electron microscopy studies show that average size of particles ranges from tens to thousands nanometers and thickness consists ten or more graphene layers. We found that conductivity of GNP is of electronic nature. The real and imaginary parts of complex permittivity in the microwave range and electric conductivity at low frequencies were found to be a nonlinear function of a volume content of GNP in GNP/PCTFE composite. It could be explained by a presence of the percolation threshold equals to 0.5 wt.%. Low percolation threshold of GNP/PCTFE composite as self-organized 3D structure, could be a certificate of high surface energy for the particles strongly interacting with the surrounding media.

Synthesis And Characterisation Of Polyaniline (PAni) Membranes For Fuel Cell

Franco D.R. Amado;Satheesh Krishnamurthy

Advanced Materials Letters, 2016, Volume 7, Issue 9, Pages 719-722
DOI: 10.5185/amlett.2016.6127

Over the past decade or so, alternative energy plays a pivotal role in addressing challenges posed by nature. Polymer electrolyte membrane fuel cell is one of the promising alternative energy and there has been significant research and technological investments done in this field. The key information and future prospective of the field is energy conversion and storage, both of which are essential in order to meet the challenges of global warming and the limited fossil fuel supply. However, polymer membrane in particular plays a crucial role in advancing this technology further. The utilization of conducting polymers in manufacturing membranes combining their electrochemical properties along with mechanical properties is of primary importance to enhance the efficiency of this system. In the present study blends of high impact polystyrene (HIPS) and polyaniline (PAni) were obtained with the aim of producing membranes for fuel cell. HIPS and PAni were dissolved in tetrachloroethylene, a common solvent for both materials. After dissolution, PAni was dispersed in an HIPS polymeric matrix. The membranes were molded on to glass plates using a laminator to keep thickness constant, and the solvent evaporated slowly for 24 h under room temperature. The amount of polyaniline used was 10 and 20 % weight. The electronic and structural properties were carried out using X-ray photoelectron spectroscopy (XPS), Thermogravimetric Analysis (TGA) Raman spectroscopy, Scanning electronic microscopic (SEM). The analysis indicate that PAni incorporation and its dispersion into the polymeric matrix modifies the membranes properties and show improvement in efficiency.