Preparation And Properties Investigation Of Epoxy Coatings Modified By Montmorillonites

Varnish coating, organophilic montmorillonite (OMMT) epoxy polyamide coating andpolyaniline/organophilic montmorillonite (PANI/OMMT) epoxy polyamide coating havebeen studied in this work. The study focused on the effects of the different modifiedmontmorillonites on the properties of epoxy coating.The cation exchange reactions and in-situ intercalation polymerization method were usedto modify the natural clay. The structure and properties of the modified clay werecharacterized by IR, XRD, contact angle test and sedimentation experiment.Epoxy coatings containing OMMT or PANI/OMMT were prepared on the carbon steelpanels. The corrosion protection of the coatings was studied by Water Absorption Test,Electrochemical Impedance Spectroscopy (EIS) and Pull-Off Adhesion Test. The images ofthe cross-section of the coatings and the filler distribution in the coatings were observed bySEM and TEM. Tension test and differential scanning calorimeter (DSC) test were used tostudy the effects of the different modified montmorillonites on the mechanical properties andthermal properties of epoxy coating. The following results were obtained:1. The parameters of the cation exchange reactions and in-situ intercalationpolymerization method were abtained; wet OMMT was used to prepare PANI/OMMT duringthe in-situ intercalation polymerization progress.2. After modified, the lateral dimensions of OMMT or PANI/OMMT layers increased tosome extent. The hydrophobic property of the modified montmorillonites was enhanced sothat they had good compatibility on the interface with epoxy resin. It was also confirmed thatthe properties of PANI/OMMT powders have been improved more remarkably than those ofOMMT powders.3. The modified montmorillonites could form “Labyrinth Effect” in epoxy coating,which could increase the tortuosity of diffusion pathway of the electrolyte solution andimproved the corrosion protection of the coating.4. The toughening and reinforcing of the coating could be obtained at the same time withadding the modified错误！链接无效。. The improvement of mechanical properties played apositive role on the corrosion protection ability of the coating.5. OMMT had more effect on the barrier properties of coating, less effect on the adhesion strength between the coating and the metal. However, PANI/OMMT not only couldincrease the charge transfer resistances Rt, inhibited the corrosion reaction and improved thecorrosion resistance of epoxy coating, but also could improved the adhesion strength of thecoating so that the corrosion resistance of PANI/OMMT coating was further enhanced.6. The protection ability of OMMT coating decreased with increasing the content ofOMMT in the coating, and the best properties of OMMT were obtained on the addition of1wt%-3wt%for OMMT in the epoxy coating. However, the protection ability ofPANI/OMMT coating increased with increasing of PANI/OMMT, and the most appropriateof the addition of PANI/OMMT was between5wt%and10wt%.