Study of modern paint and varnish coatings of cars produced by "UAZ" and "Volkswagen"

The article presents the results of a study of samples of factory paint and varnish coatings of cars of the "UAZ" and "Volkswagen" model series in accordance with the methods of studying paint and varnish coatings of vehicles in force in the system of forensic departments of the Ministry of Internal Affairs of Russia. When carrying out the study, a set of recommended methods for studying paint and varnish coatings was used - optical microscopy, infrared spectroscopy, electron scanning microscopy with X-ray spectral microanalysis. In the course of the work, the morphological features of the investigated each layer of the studied paint and varnish coatings were determined, and the infrared spectra of these layers were also recorded and interpreted. Based on the analysis of infrared spectra, the qualitative molecular composition of the main components of soils, enamels and varnishes of paint and varnish coatings was determined. Electronic images of cross-sections of paint-and-lacquer coatings of UAZ and Volkswagen vehicles were obtained, as well as X-ray spectra of each layer. The data obtained made it possible to generalize and compare the characteristic features of paint and varnish coatings of each manufacturer. So, for paint and varnish coatings manufactured by Volkswagen, the following characteristics have been determined: the first primers of the samples are made on the basis of a polyester binder containing titanium dioxide in the mineral part, the second primers (fillers) are made on the basis of an acryl-urethane or polyacrylate binder with various modifiers, containing barium sulfate, titanium dioxide and other fillers, the lacquer layers are made on the basis of an acrylic-urethane binder modified with styrene and melamine. The paint and varnish coatings produced by "UAZ" were characterized by the following features: the first primers were made on the basis of an epoxy-ester binder containing various fillers. In the manufacture of the second primers (fillers), an alkyd binder modified with melamine can be used. The available lacquer layers are made on the basis of a polyacrylate binder modified with styrene and melamine. The identified groups of features make it possible to differentiate the paint and varnish coatings of cars of the UAZ and Volkswagen model lines within the framework of the examination of materials, substances and products.

Polar migration behavior of phosphonate groups in phosphonate esterified acrylic grafted epoxy ester composites and their role in substrate protection

Epoxy resin is widely used in metal surface protection, because of corrosion resistance and adhesion. However, it’s water solubility, oxygen, and water impermeability are not enough. In this paper, linoleic acid (LOFA) and epoxy resin (E20) were used to synthesize epoxy ester (EL) and grafted with phosphonate esterified acrylic resin (AR-P) to prepare acrylic grafted epoxy ester (EL@AR-P). After modification, water solubility and film-forming property were improved, and the oxygen transmission rate (OTR) and water vapor transmission rate (WVTR) decreased. At the addition of PM-2 at 2%, the OTR, WVTR, and water-uptake rate decreased by 12.9%, 25.0%, and 12.1%, respectively. Subsequently, the modified material was subjected to electrochemical impedance spectroscopy. The low-frequency impedance of EL@AR-P2 is three times higher than EL@AR-P0. After 16 days of immersion, the low-frequency impedance of EL@AR-P2 is 20 times higher than EL@AR-P. Energy dispersive spectrometer and X-ray photoelectron spectroscopy results showed that the P elements were concentrated on the substrate surface and found the presence of P–O–Fe bonds, demonstrating that the phosphonate groups were migrated to the substrate surface to form a chelate layer with the substrate and enhancing the coating adhesion and corrosion resistance. This paper modifies the molecular structure of epoxy resin, which is expected to be an excellent material for anti-corrosion coatings.

APPLICATION OF DYNAMIC MECHANICAL ANALYSIS FOR UV-CURED COATINGS

The present study is about soya epoxy ester which was made by epoxy resin and fatty acid. Oleochemical polyols were prepared after the soya epoxy ester reacted with various hydroxyl and cellulose based derivatives. These oleochemical polyols were changed to urethanes prepolymers by reacting NCO groups of TDI and IPDI. By utilizing the reaction of NCO end group of urethane with HEMA, these urethanes were transformed in to urethane acrylate oligomer. By mixing the oligomers with various reactive diluents, UV curable coating compositions were derived. The methodology was based on dynamic mechanical analysis. The UV cured samples from cellulose based oleochemical polyols exhibit good mechanical and thermal properties. Their mechanical properties are more dependent on double bonds from unsaturated contribute to curing with extra cross-linking by an oxidative mechanism.