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Active anodic zinc content below 90 wt.% does not support sufficient electrical contacts but higher contents cause high porosity of traditional liquid zinc-rich paints (ZRPs). To resolve this problem, our proposal is the application of highly dispersed polypyrrole (PPy) coated alumina inhibitor particles (PCAIPs) in zinc-rich paint compositions. Using these nano-size inhibitor particles at concentrations from 4.55 to 0.85 wt.%, hybrid paints were formulated with zinc contents ranging from 60 to 85 wt.% at the same time. Submicron morphology and nano-scale structure, spectroscopy characteristics and electrochemical properties of the PCAIPs were studied by transmission electron microscopy (TEM) and rheology, Fourier-transform infrared spectroscopy (FT-IR) and cyclic voltammetry (CV) in first part of the work. In the second part, electrolytic corrosion resistivity of two sets of paint coatings were salt-spray chamber and immersion tested with 5 wt.% aqueous solution of sodium chloride. Active corrosion prevention ability of the saltspray tested coatings was evaluated in compliance with ISO recommendations. Dielectric properties of the coatings during the immersion tests were monitored by electrochemical impedance spectroscopy (EIS). Corrosion tested area of the coatings was investigated by glowdischarge optical emission spectroscopy (GD-OES) to disclose infiltration of corrosive analytes and oxygen enrichment in the cross-section of the primers in comparison with their pristine states. Morphology of the zinc pigments was examined by scanning electron microscopy (SEM), and quality of steel specimens and the interfacial binder residues by X-ray photoelectron spectroscopy (XPS) as well as FT-Raman and Mössbauer spectroscopy. The results of both types of corrosion tests evidenced efficient utilisation of sacrificial anodic current for galvanic protection and improved barrier profile of the hybrid coatings, along with the PCAIP inhibited moderate selfcorrosion of zinc. As a result of well balanced active/passive function, the hybrid coating 2 containing zinc at 80 wt.% and PCAIPs at 1.75 wt.% embedding PPy at 0.056 wt.% indicated the most advanced corrosion prevention. Galvanic function of the hybrid paints is interpreted on the basis of size-range effect and spatial distribution of the alumina supported PPy inhibitor particles and basic electrical percolation model considerations.

Apparent molar volumes of sodium decyl (NaDS), dodecyl (NaDDS), and tetradecyl sulfate (NaTDS) are calculated from densities measured by a vibrating capillary densitometer in normal and 99.85% heavy water at 25 °C. On the basis of a pseudophase approach, the apparent molar volume of monomers is separated from that of aggregated surfactants. With the concept of group additivity being utilized, the apparent molar volume of the headgroup is separated from that of monomer and aggregated alkyl chains. The apparent molar volumes of a particular surfactant in normal and in heavy water solutions are slightly, but significantly, different. Both the magnitude and the direction of this isotope effect were found to depend on alkyl chain length. From the apparent molar volume of aggregated alkyl chains (determined in normal water), the (apparent) density inside the core of sodium alkyl sulfate micelles is calculated, and its comparison with the bulk densities of liquid n-alkanes indicates that the packing of the alkyl chains in the two media should be different. When the infinite dilution, aggregated apparent, and bulk molar volumes of the CH3 and CH2 groups are compared, the number of solvent molecules that penetrated into the micellar core per alkyl chain is estimated and a good agreement is found with an upper limit arising from a small-angle neutral scattering study. 7 This work is supported by the OTKA Foundation of the Hungarian Academy of Sciences.

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