Preparation of conductive natural rubber using polypyrrole

Abstract

Natural rubber particles were coagulated by concentrated electrodecantation method on anode. The thickness and weight of the rubber sheets were dependent on applied voltage and coagulation time. Subsequently, a multi-components system incorporating polypyrrole and prepared natural rubber sheets was prepared in an electrochemical cell yielding conductive natural rubber sheets. A suitable condition for best conductive natural rubber sheets was (i) 0.05 M pyrrole monomer in the reaction of 2.00 MLiClO4 in methanol at 25 ℃ in nitrogen gas flow lasted for 6 h and (ii) a voltage of 4V was applied to a palladium (Pd) working electrode. The conductivity of polypyrrole on natural rubber sheets was 10-3 S/cm and it gradually dropped with time. It was also decreased when stored in either acid or base solutions or stored in contact with moisture. Powder polypyrrole was prepared by chemical oxidation reaction in 2.5 M FeCl3 in methanol at 0 ℃ for 20 minute. It was mixed physically with coagulated natural rubber by chemical dissolution method, and the conductivity was measured. However, the electrical conductivity of conductive natural rubber prepared by electrochemical method was higher than that of physically mixed powder polypyrrole and natural rubber.