Evaluation of nanosilicate filled poly (vinyl chloride-co-vinyl acetate) and epoxy coatings

The corrosion protection, mechanical and thermal properties of nanoclay filled epoxy and poly (vinyl chloride-co-vinyl acetate) (VYHH) resins have been studied. Nanoclay was incorporated into VYHH at 0%, 0.5% and 1.5%wt loadings, and into epoxy at 0% and 1.5% loadings. Steel substrates were prepared and coated with each of the prepared coatings. Some of the samples were submerged in a tank containing 5% NaCl solution and tested periodically using electrochemical impedance spectroscopy (EIS) to study the effect of the nanoclay on the corrosion protection of the coatings. Films were cast from each system to be used to evaluate the mechanical performance of the coatings. Notched and unnotched samples were cut from the films and some were submerged in the 5%NaCl solution while some were left unsubmerged as controlled samples. EIS measurements showed that VYHH/0.5%nanoclay provided superior barrier protection. The nanoclay filled epoxy exhibited increased barrier properties after 21 days. The tearing energy of the neat VYHH coating decrease by 27% after submersion, while the nano coatings showed a slight increase. The neat epoxy showed no change in the tearing energy after submersion, while that of the nano coating was increased by 14% after submersion. Differential scanning calorimetry (DSC) results showed that the nano coatings have improved the thermal barrier properties compared to the neat.