Preparation of conductive polypyrrole composites by in-situ polymerization

Two kinds of conductive polypyrrole composites were prepared by in-situ polymerization of pyrrole in a suspension of chlorinated polyethylene powder or in a natural rubber latex using ferric chloride as oxidizing agent. The preparation conditions were studied and the results showed that it is better to swell the chlorinated polyethylene powder with the monomer first, followed by addition of the oxidant, than to add the oxidant first, and that conversion can reach 98% for 6h at room temperature. The conductivity percolation threshold of the composite is about 12%. The composites can be processed repeatedly, exhibiting a maximum tensile strength over 9MPa and a maximum conductivity near 1 S cm(-1). The polypyrrole/natural rubber composites were prepared successfully by using a nonionic surfactant (Peregal O) as stabilizer at pH less than 3 with a molar ratio of FeCl3/pyrrole = 2.5 below 45 degrees C. The latter composites show a low conductivity percolation threshold about 6%, a maximum tensile strength over 10MPa and a maximum conductivity over 2S cm(-1). The composites were characterized by FTIR and TGA. The polypyrrole/chlorinated polyethylene composites are very stable in air and almost no decrease of conductivity was observed for over 10 months examined. (C) 1999 Society of Chemical Industry.