Electrically conducting polymers in thermosets and thermoplastics.

摘要

Due to strict regulations on the usage of heavy metals as additives in coating industries, the search of an effective organic corrosion inhibitor to replace those metal additives has become essential. In this study, the use of electrically conducting polymers in thermosets for corrosion prevention has been examined. Polyaniline/4-dodecylphenol complex (PANi/DDPh) has been shown to be an effective organic corrosion inhibitor. The concentration dependence of the additive is evaluated and 20 wt.% of the complex been found to have an optimal effect in a polyacrylic-based thermoset. Polyaniline is found to be oxidized by the hardener. The oxidized form of polyaniline provides more corrosion protection than the emeraldine base since the value of the standard reduction potential is 0.041V for the oxidized form of PANi and {dollar}-{dollar}0.559V for the emeraldine base form of PANi, respectively. Therefore, the hardener acts as an oxidant and retains PANi in its oxidized state. Moreover, the surfactant improves the wet adhesion property between the coating and the metal surface. The undoped oxidized PANi is stable for more than one year and the doped oxidized PANi is stable for more than four months under the atmospheric environment in blends with the polyacrylic-based thermoset.; The morphology of the polymer blend influences strongly on the mechanical and electrical properties. In particular, the network formation due to spinodal decomposition reduces the percolation threshold and provides anti-static property without sacrificing the mechanical properties of the matrix. In this study, the ternary blend of conducting polymer with thermoplastics was studied in order to evaluate the possible network formation due to spinodal decomposition. The ternary conducting polymer blend of polystyrene/poly(vinyl methyl ether)/poly(3-dodecylthiophene) (PS/PVME/PDDT) was chosen as the model system. PS/PVME/PDDT forms networks due to spinodal decomposition depending on the initial composition of the blend and the rate of solvent evaporation. The sample can exhibit differences in the electrical conductivity through different preparation procedures. The observation of the two phase separation temperature behavior and the appearance of the conducting polymer in the minor phase support the multiple percolation theory of the polymer blends.