Controlled Release of Novel Volatile Corrosion Inhibitor (VCI) Nanoparticles Incorporated in Low Density Polyethylene (LDPE) Films for Steel Coverings: Correlation of Experimental Results with Molecular Dynamics Simulation

Abstract

The compositions of 10 different VCI compounds were optimized. Low density polyethylene (LDPE), ECA-5 copolymer (poly(ethylene-co-methyl acrylate) as an ethylene based coupling agent) and the prepared VCI compound, so called BFA-200, were processed in a twin screw extruder followed by a film casting method to make films. The 80/20 LDPE/ECA-5 composition was determined as the optimized VCI unfilled blend having the maximum mechanical properties for the film processing; the BFA-200 VCI nanoparticles (5, 10 and 15%) were added to this composition. Measurement of the controlled release of the VCI within the LDPE/ECA-5/BFA-200 80/20/15 sample was carried out using thermo-gravimetric analysis (TGA). The TGA method was also used for determination of the VCI content after periods of 3, 6 and 12 months in polyethylene bags stored at ambient conditions. There was a significant difference in the release of VCI agent for the blends as compared to that of VCI incorporated in only LDPE. The preservative quality of the blend films was tested on steel plates using the TL8135-002 standard. There were acceptable degrees of corrosion with all of the virgin blends containing BFA-200, especially 10% upward. However, there was a different behavior after each time period, in good accordance with the release tests. Moreover, a molecular dynamics (MD) simulation was performed to determine the diffusion of the VCI molecules within pure LDPE and the LDPE/ECA-5 blends. There was a decrease in the simulated diffusion of the VCI material through the blends with addition of the ECA-5 content which fitted well to the experimental data.