Conductive plastics made from natural, renewable, environmentally friendly soybeans

Polymer matrix composites with carbon black are very interesting materials. This is because the carbon black can be used as filler material and can beneficially modify the electrical and mechanical properties of the used matrixes. The polymer components of these composites are traditionally made using oleo-polymers; however, an alternative is to use natural and renewable sources as soybean oil, linseed oil, sunflower oil, etc.

Polymers derived from those natural oils can be tailored for engineering and aeronautical applications by reinforcing them with natural and synthetic fibers and clays.

Recent work by S. Hernández-López, E. Vigueras-Santiago, J. Mercado-Posadas and V. Sanchez-Mendieta from Universidad Autónoma del Estado de México investigated the electrical properties of composites based on acrylated-epoxidized soybean oil (AESO)-co-butyl methacrylate (BMA) with carbon black (CB).

The composites were obtained by in situ copolymerization of the above-mentioned monomers with Vulcan XC72 CB. Examination of the resultant materials has shown that the transition from the dielectric state to the conductive state could be achieved by:

Varying the carbon black concentration in the polymeric matrix

Varying the different monomers proportion that conform the polymer matrix
The researchers found that when carbon black concentration is changed the electrical resistivity shows a typical behavior of ordinary conductive polymer composites. However, the electrical percolation threshold for the AESO:BMA system is reached at lower values than those reported for commercial oleo polymer-based composites. These findings could lead to commercial applications of the materials in antistatic shielding materials and solven sensors.