Thermomechanical studies of poly(aniline)/poly(methyl methacrylate) blends: Relationship with conducting properties

We report on the first dynamic mechanical studies of blends of conducting p olymer poly(aniline) (PANI) in an insulating matrix that exhibit ultralow e lectrical percolation threshold. Whereas the matrix undergoes an irreversib le flow slightly above its glass-rubber transition temperature, blends with PANI mass fraction as low as 1% show a well-defined rubber plateau with a stability range of ca. 100 K. These results corroborate the image of a rami fied network of conducting phase, inferred from electrical results. In situ resistance measurements during tensile testing also probe the conductive n etwork. The increase of conductivity in the elastic regime could be interpr eted as a consequence of a better alignment of PANI bundles.