Research on the Interface Modification of Epoxy Resin/Metallic Substrates and Epoxy Resin/Pigment
|School||Harbin Engineering University|
|Keywords||Anticorrosive Coatings Interface Modification Adhesion Water Absorption|
Epoxy coatings are the main anticorrosion coatings which are due to their excellent protective properties against corrosion. However, the low adhesion between the epoxy coatings and the metallic substrates and many defects in the coating limited the use of epoxy coatings in many applications, such as in the deep ocean and circumstances with alternate pressures etc. These issues were resulted from the low interaction force between the epoxy resin and the metallic substrates and the bad compatibility between the epoxy and the pigment. In the present work, epoxy resin was modified with some activation groups grafted onto epoxy and formed the chemical bonding to enhance the adhesion between epoxy coatings and metallic substrates, the pigment was also modified with epoxy group to improve the properties of the coating.The modified epoxy resin which has both carboxyl group and the epoxy groups was prepared by grafting the tartaric acid onto the epoxy E44. The modified epoxy was coated on the surface of the high strength steel to form chemical bonding with the high strength steel. The modified epoxy film was more compact after treated at 120℃. Pull-off test implied that the modified epoxy resin pretreatment had increased the adhesion from 5.75 MPa to 9.78 MPa and the increasing extent reached 70%. The fracture interface of the pretreated specimen was in the coatings contrast to that the specimen unpretreated was at the interface between the steel and coatings.The modified epoxy resin has both epoxy group and alkoxy silane functional group was prepared by grafting the 3-Triethoxysilylpropylamine APTES onto the epoxy E51. SEM and FTIR proved that the increasing immersion time of the high strength steel in the hydrolysis solution could influence the adsorption quantity and the state of the modified epoxy on the high strength steel. Pull-off test implied that the modified epoxy resin pretreatment had increased the adhesion from 5.75 MPa to 10.12 MPa and the increasing extent reached 76%.The modified mica iron oxide which has exoxy group was modified by grafting epoxy resin E44 onto the mica iron oxide. According to the results of SEM, the dispersion of the modified mica iron oxide was better than un-modified mica iron oxide, and the pieces of the modified mica iron oxide tend to arrange parallel to the surface of the steel. The modified mica iron oxide led to decreasing of the water absorption. When the content of the modified mica iron oxide was 5%,the water absorption was the lowest.The modified glass flake which has epoxy group was prepared by grafting epoxy resin E44 onto the glass flake.The modified glass flake arranged more compactly on the surface of the steel than un-modified glass flake and led to decreasing of the water absorption in the early immersion time.