Preparation And Characterization Of Inorganic Modified Polyaniline/Epoxy Coatings

Epoxies are widely used in heavy-duty protective coatings such as marine and petroleum pipeline because of their excellent chemical resistance,high adhesive and mechanical strength.However,their lifetime is greatly affected due to their fragility and low scratch resistance.In general,incorporation of polyaniline nanomaterials can significantly increase the scratch resistance and anti-corrosion performance of coatings,while its effect is deteriorated when the coatings are used under high temperature and high salinity condition.Therefore it is of great importance to increase durability of coatings in aggressive conditions by searching simple and effect method of tougheningIn this work,PANI/epoxy coatings with different content of tephra microparticles(TMP)and basalt microplates(BMP)were prepared respectively.The coatings were characterized by salt immersion test(95oC,12wt% NaCl)and electrochemical impedance spectroscopy(EIS).The effect of TMP and BMP on the protective performance of epoxy coatings was evaluated.Contact angle,water absorption and adhesion strength of some coatings were also tested.In addition,the thermal shock test and high temperature-high pressure immersion test were conducted to study the toughening effect of TMP/epoxy coating.The experiment results indicate that incorporation of TMP into PANI/epoxy coatings can effectively improve coating's protective performance,especially for hybrid coating with 10.0wt% TMP which had a resistance of 1.27×109 ohms·cm2 after 60 days immersion.Besides,the results of thermal shock test and high temperature-high pressure immersion test also showed that the toughening effect of TMP improved the corrosion protection performance of coating to some extent.The parallel distribution of BMP in the coating matrix intensively increased barrier resistance of coatings,especially for hybrid coating with 6.0wt% BMP which had a resistance of 4.11×1010 ohms·cm2 after 60 days immersion.The incorporation of BMP and TMP can increase the adhesion strength of epoxy coating and decrease the water absorption of PANI/epoxy hybrid coating.The results of SEM and XPS demonstrated that the high temperature and high salinity environment do damage the coating,and that the iron oxide consisting of a layer of ?-Fe2O3 followed by a layer of Fe3O4 was formed.In a word,incorporation of TMP and BMP into PANI/epoxy coatings can significanty improve coating's protective performance.