Electronic transport properties of graphene-polymer nanocomposites
It has been studied the electronic properties of compounds formed by graphene and polymers. The study makes a comparative analysis between experimental and computational results. To make an experimental measurement of the electronic properties, we deposited graphene nanoparticles over a polypropylene matrix. The deposition was made in several stages. We added different percentages of graphene nanoparticles to the polymer matrix using the melt compounding technique, and we studied microwave adsorption. The experimental conductivity was measured using electrochemical spectroscopy impedance equipment. The second part consists of computational calculations, in which we studied the electronic properties of a graphene sheet under one polypropylene molecule with different degrees of polymerization. We observed a strong percolation phenomenon with a percolation threshold of around 18% of MLG nanoparticles. Before the percolation threshold, the charge carriers are constrained in the polypropylene molecule, making the system an insulating material. After the percolation threshold, the charge carriers are constrained in the graphene, making the system a conductor material. Incorporating the quantum effects and the percolation phenomenon makes it possible for the theoretical conductivity to be close to the experimental conductivity.
To extrapolate our research to several polymers systems with graphene, we have made a stochastic study of the problem to observe how the phenomenon of percolation on different graphene-polymer nanocomposites. We simulate the deposition and transport phenomena with a Monte-Carlo simulation. We compared our results with the experimental studies, and we obtained a reasonable estimation of the percolation threshold and the observed conductivity.