Comparison of the Corrosion Inhibition Ability of Different Coumarate-Based Compounds Incorporated into Waterborne Binders

One of the most widely applied methods for the mitigation of corrosion is to cover metallic surfaces with polymeric coatings; however, the barrier properties provided by the polymer may not be enough to prevent corrosion. To improve the performance of the coatings, the incorporation of corrosion inhibitors in their formulation can be done to provide active protection to the system. Among the organic corrosion inhibitors, p-coumaric acid (p-CA) is promising for corrosion protection. Therefore, in this work, the corrosion protection efficiency of four p-coumaric-based inhibitors, methyl (H1), butyl (H4), trifluoromethoxy (HCF3), and p-4-ethyloxymethacrylate p-coumaric acid (HMA), is investigated. The inhibitors are incorporated into environmentally friendly waterborne polymeric binders by batch miniemulsion polymerization. The barrier corrosion protection of the coatings produced from these hybrid latexes is analyzed by electrochemical impedance spectroscopy (EIS) of the intact and scratched coated steel substrates. Of the intact coatings, the one with H1 showed the best response, with impedances of 10(6.3)-10(6.7) Omega and phase angles of 82-84 degrees, considerably higher than the control without inhibitor (10(5)-10(5.2) Omega and 60-66 degrees, respectively). The better performance of H1 has been attributed to its higher solubility in the media. However, the best impedance results for the scratched films have been obtained for the coating with HMA, as the impedance was maintained at similar to 10(4.3) Omega for 24 h, while the impedance drops from similar to 10(4.6) to 10(4.1) Omega for the control scratched sample. As HMA is attached to the polymeric chains, it is likely able to protect the exposed metallic area without completely leaching from the coating, thus explaining why it is able to maintain its performance. The EIS analysis also strongly suggests that the inhibitors have an additional protective effect through increasing pore resistance and decreasing metal corrosion as indicated from the higher R-pore and lower C-dl data extracted from the fits.We are thankful for the financial support received from the Basque Government (IT-1525-22), from the Spanish Government (MINECO PID2021-123146OB-I00 and MICINN PDC2021-121416-I00), and from Deakin University

Lignin-Derivative Ionic Liquids as Corrosion Inhibitors

Corrosion is a significant problem that negatively affects a wide range of structures and buildings, resulting in their premature failure, which causes safety hazards and significant economic loss. For this reason, various approaches have been developed to prevent or minimize the effects of corrosion, including corrosion inhibitors. Recently, biobased inhibitors have gained a certain interest thanks to their unique properties, eco-friendliness, and availability. Among all the green precursors, lignin is of particular interest, being a natural polymer that can be obtained from different sources including agricultural residues. Corrosion inhibitors based on ionic liquids (ILs) also present interesting advantages, such as low volatility and high tunability. If combined, it may be possible to obtain new lignin-based ILs that present interesting corrosion inhibitor properties. In this work, the inhibition properties of new biobased lignin ILs and the influence of anions and cations on the corrosion of mild steel in an aqueous solution of 0.01 M NaCl were investigated by Potentiostatic Electrochemical Impedance Spectroscopy (PEIS) and Cyclic Potentiodynamic Polarization (CPP). Moreover, the surface was characterized using SEM, EDS, and optical profilometry. The IL choline syringate showed promising performance, reducing the corrosion current after 24 h immersion in 0.01 M sodium chloride, from 1.66 µA/cm2 for the control to 0.066 µA/cm2 with 10 mM of the IL present. In addition to its performance as a corrosion inhibitor, both components of this IL also meet or exceed the current additional desired properties of such compounds, being readily available, and well tolerated in organisms and the environment

PREPARATION OF POLYMER MATRIX COMPOSITE MATERIALS WITH NIR REFLECTIVE PROPERTIES

In this work, the dispersion of a NIR reflective organic black pigment in polymeric matrices and the influence of other additives on the film processing as well as its mechanical properties and thermal performances were investigated. Other factors such as the concentration of the reflecting material, distribution of the particles within the matrix, and film thickness were evaluated. The aim of the work is the preparation of an efficient NIR reflective polymeric composite for greenhouses or automotive applications

Modeling heavy metal release in the epiphytic lichen Evernia prunastri

In this study, the release of Cu2+ and Zn2+ was investigated and modeled in the epiphytic lichen Evernia prunastri. Samples were incubated with solutions containing these metals at ecologically relevant concentrations (10 and 100 μM) and then transplanted to a remote area and retrieved after 1, 2, 3, 6, 12, and 18 months. The results showed that, after 12 months, all samples faced similar metal reductions of ca. 80–85%, but after this period, all the involved processes seem to be no longer capable of generating further reductions. These results suggest that the lichen E. prunastri can provide information about environmental improvements after exposure to high or very high pollution levels in a relatively short period of time

Enhancing the cooling properties of low-density polyethylene films by combining near-infrared reflective additives

In the last years, the rising temperature caused by global warming brought the research to find new efficient solutions to lower the temperature of buildings and reduce the consumption of electrical energy for air conditioning. In this work, we propose the combined use of organic and inorganic near-infrared (NIR) reflective additives in low-density polyethylene (PE) films as an accessible plastic coating with enhanced cooling features. Two ‘cool’ pigments, the inorganic Sicopal® Black (Si Black) and the organic Paliogen® Black (Pa Black), were investigated for black-tinted coatings, while TiO2 (TI) and glass bubbles (GB) were tested for opaque white coatings. The additive's size and concentration influence the composite processing, and their ultimate optical properties were determined in terms of total solar reflectance (TSR) and cooling effect under solar radiation. TI and GB dispersed in PE showed the highest TSR, whereas the organic Pa Black confirmed its superior reflective features with respect to the traditional carbon black (CB). Moreover, a significant increase in the TSR occurred when TI or GB was added to the black pigments (12.7% and 13.6%, respectively). TSR increasing led to a cooler black-tinted PE film under solar irradiation. When using reflective pigments, a cooling effect of about 10°C was measured with respect to the traditional CB

Modeling heavy metal release in the epiphytic lichen Evernia prunastri

In this study, the release of Cu2+ and Zn2+ was investigated and modeled in the epiphytic lichen Evernia prunastri. Samples were incubated with solutions containing these metals at ecologically relevant concentrations (10 and 100 μM) and then transplanted to a remote area and retrieved after 1, 2, 3, 6, 12, and 18 months. The results showed that, after 12 months, all samples faced similar metal reductions of ca. 80–85%, but after this period, all the involved processes seem to be no longer capable of generating further reductions. These results suggest that the lichen E. prunastri can provide information about environmental improvements after exposure to high or very high pollution levels in a relatively short period of time