Mechanism of charge transport in castor oil-based polyurethane/carbon black composite (PU/CB)

• Published in: Journal of non-crystalline solids Vol. 358; no. 2; pp. 270 - 275
• Main Authors: Silva, M.J.da, Kanda, D.H.F., Nagashima, H.N.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier B.V 15.01.2012; Elsevier
• Subjects: Applied sciences; Carbon black; Castor oil based polyurethane; Composites; Conductance; Conduction mechanism; Electrical, magnetic and optical properties; Exact sciences and technology; Forms of application and semi-finished materials; Hopping (conductivity); Mathematical models; Networks; Organic polymers; Physicochemistry of polymers; Plutonium; Polymer industry, paints, wood; Polyurethane resins; Properties and characterization; Resistor–capacitor network; Statistical analysis; Statistical model; Technology of polymers; Resistor–capacitor network; Conduction mechanism; Carbon black; Castor oil based polyurethane; Statistical model; Electrical conductivity; Volume fraction; Drude model; Tunnel effect; Animal origin; Dispersion reinforced material; Two dimensional model; Composite material; Resistor network; Polyurethane; Resistor-capacitor network; Transfer matrix method; Percolation; Microstructure
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/j.jnoncrysol.2011.09.032

In order to identify and quantify the conduction mechanisms involved in the transport process, castor oil based polyurethane/carbon black composite (PU/CB) was introduced in a statistical model that reproduced the ac conductivity of composite PU/CB measurements by the application of a transfer-matrix technique. The simulation is based on virtual composite sample generation represented by a two-dimensional model of a resistor–capacitor network. The network represents a microstructure that contains both insulating (polyurethane) and conductive regions (carbon black). Drude's formula was applied in the conductance calculation between two neighboring sites in the CB particles or aggregates, and Miller–Abrahams formula in conductance between two neighboring sites of the polymeric matrix. The theoretical–experimental adjustment indicates that, at low frequencies (below 103Hz), the transport mechanism by charges hopping in the polymeric matrix is dominant. On the other hand, at high frequencies (above 105Hz) electron conduction in carbon black, given by Drude's formula, is dominant. The ac conductivity in the polymeric matrix is determined by the competition of two processes, one connected to hopping between the nearest sites with large energy difference or to hopping between the sites beyond the nearest neighbors with small energy difference. ► We introduced a statistical model based on networks of resistors and capacitors. ► This model reproduces the alternating conductivity of PU/CB composite. ► The model indicates that conductivity in the matrix is governed by Mott's model. ► The system became conductive due to the tunneling effect between particles.