Study Of Composite Methods For Polyaniline's Application And It's Anti-corrosion Properties

The application of polyaniline (PANI) is restricted by its poor solubility, infusible and almost non-processable properties. In order to improve the processability of PANI, two composite methods such as mechanical mixing and in-situ emulsion polymerization were studied and the blending conditions and polymerization technology were optimized. Moreover, the anti-corrosion properties of polyaniline were studied in detail.Polyaniline was dispersed in epoxy resin and composite coatings were prepared by the simple mechanical polishing. It was found that the suitable dosage of polyaniline in epoxy resin was 0.6% (mass percentage). The corrosion prevention of composite coatings was investigated through the salt spray test and electrochemical method. The results showed that the epoxy composite coating mixed with phosphoric acid, oxalic acid and acrylic acid-doped polyaniline was provided with excellent protective function for carbon steel; however, the epoxy composite coating mixed with hydrochloric acid, sulfuric acid, acetic acid doped-polyaniline and de-doped polyaniline lose the protective effect fastly during immersing.Polyaniline was dispersed in acrylate pre-emulsion through ultrasonic vibration in assistance with mechanical stirring. Result showed that the stability of pre-emulsion reduced gradually with increasing amount of polyaniline; Different polyaniline showed different dispersing stability in acrylate pre-emulsion: Hydrochloric acid and acrylic acid-doped polyaniline was provided with the best dispersing properties in the acrylate pre-emulsion, the following was sulfuric acid and acetic acid-doped polyaniline; However, dispersing properties of oxalic acid-doped polyaniline in acrylate pre-emulsion was poor and phosphoric acid-doped polyaniline showed the worst dispersing properties.Based on condition of the pure acrylate emulsion polymerization, using multi-step polymerization technology, polyaniline-polyacrylate copolymer was obtained by in-situ emulsion polymerization. The morphology of copolymer was fiber with cross-linking network. It was reasonable to consider that in-situ emulsion polymerization of acrylate occurred on the surface of PANI nanofibers which was the reactive position and finally covered the surface of fibers. The study of Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA) and Salt-spray Experiment indicated that the copolymer possessed good film-forming properties, excellent high temperature-resistance and good salt spray-resistance.