The bioeconomy at work: conductive biopolymer made from soybeans

Researchers from the Universidad Autónoma del Estado de México (UAEM) and its Laboratorio de Síntesis y Caracterización de Materiales, recently investigated the electrical properties of composites based on acrylated-epoxidized soybean oil (AESO)-co-butyl methacrylate (BMA) with carbon black (CB). Their findings are reported in AZojomo, a materials sciences journal.

Polymer matrix composites with carbon black - a petroleum product - are very interesting materials. This is so 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, derived from crude oil; however, an alternative is to use natural and renewable sources as soybean oil, palm oil, linseed oil or sunflower oil.

Polymers derived from those natural oils are taking importance in different areas such as engineering and aeronautics due to the fact that their mechanical properties can be improved by reinforcing them with natural and synthetic fibers and clays, among others. Recently electrical properties were reported pointing that percolation concentration of carbon nanotubes was around 1%. So, polymers obtained from renewable sources are good candidates for being used in conductive polymeric composites:
energy :: sustainability :: biomass :: soybeans :: bioplastics :: biopolymer :: biodegradable :: conductivity :: bioeconomy ::

The composites investigated by the Mexican team 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 the 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.

More information:
Eurekalert: Conductive plastics made from natural, renewable, environmentally friendly soybeans - May 29, 2007.

S. Hernández-López, E. Vigueras-Santiago, J. Mercado-Posadas and V. Sanchez-Mendieta, "Electrical Properties of Acrylated Epoxidized Soybean Oil Polymers Based Composites", AZojmo, Open Access Rewards System (AZo-OARS) article, Volume 3 May 2007, DOI : 10.2240/azojomo0236.