Biodegradable packaging for corrosion inhibition via supercriticial fluid

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] The focus of this study is to develop a packaging material that is both biodegradable (BD) and provides corrosion protection for a packaged metal substrate. Supercritical carbon dioxide (SCCO2) was used to infuse Ecoflex® resin, a BD aliphatic-aromatic copolyester, with sodium nitrite (NaNO2), which is a common volatile corrosion inhibitor (VCI). The effects of SCF density upon the infusion depth and the corrosion prevention capability of the final product were examined. For this study, 10 g of Ecoflex® was infused with NaNO2 using SCF densities that ranged from 0.15-0.62 g/cm3. The results demonstrated that fluid density does not play a significant role in infusion depth, but temperature is significant at 95%. The corrosion protection capabilites of VCI-infused biodegradable polymer was compared to packages of VCI-infused linear low-density polyethylene (LLDPE), uninfused Ecoflex®, uninfused LLDPE, and an unpackaged control. The corrosion rates were 0.00033mm/yr, 0.00048 mm/yr, 0.00297 mm/yr, 0.00089 mm/yr, 0.00353 mm/yr, respectively. The VCI-infused packages provided the most protection, with the VCI-Ecoflex® resulting in 90.7% less corrosion. Scanning electron microscopy studies show that the film integrity was maintained during the SCF infusion process. These findings demonstrate the infusion capability of a supercritical carbon dioxide system, and help elucidate the effects of processing conditions on the infusion quality of the final product. Additionally, the corrosion protection ability of the infused films was verified.