Primena modifikovanih tanina u antikorozionim alkidnim premazima

The study of the synthesis of anticorrosive inhibitors, based on chemically modified tannins, and their use in alkyd based coatings to improve anticorrosive properties is presented in this work. Two methods of tannin modification were applied: direct method using ammonium hydroxide, ammonium hydroxide/ammonium chloride buffer or diethylenetriamine (DETA); and a two-step method including tannin modification with epichlorohydrin (ECH) in first step to produce epoxy modified tannin, ET, and further modification with heteroaromatic amines or linseed oil fatty acids (LFA) in second step. The obtained anticorrosive additives were characterized using ATR-FTIR, 1H and 13C NMR spectroscopies and elemental analysis. Epoxy, amino, hydroxyl, acid and iodine values of the synthesized inhibitors were determined according to standard methods. The prepared alkyd coating with tannin inhibitors was tested according to standard SRPS EN ISO 4628 method. Anticorrosive coating containing modified tannin based additive showed increased anticorrosive properties, good adhesion and coverage comparing to the coating with zinc phosphate additive. The alkyd coating films based on ET-LFA and ET modified with 2-amino-5- mercapto-1,3,4-thiadiazole showed best anticorrosive results.U ovom radu prikazana je sinteza antikorozionih aditiva na bazi hemijski modifikovanog tanina i njihova primena u alkidnim premazima u cilju poboljšanja antikorozionih svojstava. Prikazane su dve metode modifikacije tanina: direktna modifikacija tanina primenom amonijum-hidroksida, amonijum-hidroksid/amonijum-hlorid pufera ili dietilentriamina (DETA); i dvostepena modifikacija tanina koja u prvom stupnju uključuje modifikaciju epihlorhidrinom sa ciljem da se dobije tannin sa epoksi terminiranim funkcionalnim grupama, ET, i modifikaciju ET tanina sa heteroaromatičnim aminima ili masnim kiselinama izolovanim iz lanenog ulja (LFA) u drugom stupnju. Sintetisani antikorozioni aditivi su okarakterisani primenom ATR-FTIR, 1H i 13C NMR spektroskopija, i elementalnom analizom. Sadržaj epoksi, amino, hidroksilnih i karboksilnih grupa i vrednost jodnog broja sintetisanih aditiva određen je prema standardnim metodama. Alkidni premazi koji sadrže antikorozione aditive na bazi modifikovanog tanina ispitani su prema standardnoj SRPS EN ISO 4628 metodi. Antikorozivni alkidni premazi na bazi modfikovanih tanina pokazali su poboljšane antikorozione karakteristike i adheziju u poređenju sa alkidnim premazom na bazi cink-fosfata. Alkidni premazi koji sadrže dvostepeno modifikovani tanin sa LFA i 2-amino-5-merkapto-1,3,4-tiadiazolom pokazali su najbolje antikorozione karakteristike

Synthesis and application of thiocarbamates obtained by oxidative treatment of waste xanthate

In this paper, the optimal treatment of industrial waste consisting from xanthate and oxidation product, i.e. diisobutyl and diethyl dixanthogenate, was developed for production of flotoreagents. Waste dixanthogenate was generated during production and storage of flotation agents, i.e. potassium isobutyl (KiBuX) and potassium ethyl xanthate (KEtX), respectively. The process of waste xanthate treatment is based on the reaction of the nucleophilic heterolysis of the persulfide bond in the diisobutyl dixanthogenates by alkylamines in presence of various oxidizing agents (sodium hypochlorite, hydrogen peroxide, potassium persulfate) to produce N-alkyl-, N,N-dialkyl- and N cycloalkyl-O-isobutyl thiocarbamate selective flotoreagents. Also, analogous methodology was applied for synthesis of N-alkyl and N,N-dialkyl-O-ethyl thiocarbamate from KetX using sodium hypochlorite at laboratory and semi-industrial level. The developed method provides the corresponding alkyl thiocarbamates in a high yield and purity. The flotation efficiency was analysed using the obtained thiocarbamate on a real sample of minerals in laboratory and industrial conditions

Green corrosion inhibitors

The corrosion inhibiting possibility examination of extracts obtained from fruits of rose hip and horse chestnut was investigated. Rose hip extracted at different temperatures exhibited different corrosion inhibiting effect. Rose hip obtained at 40oC did not show any inhibiting effect in neutral pH medium, while in acidic media it expressed moderate protective impact (up to 55%) for steel and mild corrosion inhibiting impact for zinc (39%), while for aluminium and copper it did not have any inhibiting effect. Rose hip obtained at 25oC exhibited significant inhibiting effect for steel (up to 62 %) and even better for zinc (up to 72%) in neutral media. For aluminium and copper neither of Rose hip extracts showed any inhibiting effect. The Horse chestnut extract exhibits moderate to significant inhibiting effect for steel (up to 55%) and zinc (up to 60%) in neutral media. In addition to this, because of the complex chemical composition of these fruit extracts, some further electrochemical investigation is suggested, aimed to determine a single component inhibitive effect. Firstly, as one of prevailing components, tannins are examined. Linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS) were used as a testing techniques

Resistance to Pit Formation and Pit Growth for Different Tempers of AA2024 Aluminium Alloy in Presence of Benzotriazole

The paper analyses the corrosion behaviour of both naturally and artificially aged AA2024 aluminium alloy in NaCl solution in the presence of the corrosion inhibitor benzotriazole (BTA). The differences between these two aging tempers in terms of resistance to general corrosion are explained as well as the differences in terms of pit formation and pit growth. Based on the values of the polarisation resistance and the corrosion current density, the general corrosion resistance of the alloy is determined in the absence and in the presence of BTA. The resistance to pit formation and pit growth is determined on the basis of the polarisation measurements results. Scanning electron microscopy confirmed the expected differences in the appearance and size of the pits formed in naturally aged and artificially aged alloy. In the presence of the corrosion inhibitor BTA, for both aging tempers of the alloy, the corrosion resistance is significantly higher compared to the resistance in the solution without the inhibitor. The value of the polarisation resistance for both aging tempers increases over time. However, at the same time, the value of the constant phase element increases as well. An explanation for this phenomenon is provided. The calculated average value of the thickness of the adsorbed inhibitor layer on the surface of the aluminium alloy is in accordance with the inhibitor protective ability for both aging tempers. Graphi

Phosphorylated kraft lignin based flame retardant: efficient method for improvement of lignin flame retardancy and mechanical action in polyester

In this paper, the potential application of phosphorylated industrial kraft lignin (KLP) in improving flame retardant properties of unsaturated polyester/KLP composites (UPe/KLP) was studied. KLP mass contents in UPe based composites varied from 0.5 wt.% to 5.0 wt.%. The successfulness of the performed phosphorylation method, direct grafting of phosphorus chloride on KLP surface hydroxyl groups, and formation of phosphoric acid ester were confirmed via Fourier Transform-Infrared Spectroscopy (FT-IR). The effects of KLP surface functionalization and KLP mass contents on the UPe tensile properties were studied. Tensile strength (σ), elongation (ε) and Young’s modulus of elasticity (E) of the UPe/KLP composites were analyzed in relation to the structure of KLP modification. The obtained composites were tested on fire retardant properties according to the standard test method UL-94V

Ispitivanje mikrotvrdoće nezasićenih poliestarskih smola sa ojačanjima na bazi aluminijum oksida

Commercial alumina wiskers (Al2O3 w) and synthesized alumina particles via sol-gel technique (Al2O3 m) were used as reinforcement in unsaturated polyester resins (UPR). Composite materials with the addition of 0.1 wt. %, 0.25 wt. %, 0.5 wt. %, 1.0 wt. %. i 2.5 wt. % of alumina based particles were obtained. Structural analysis of used alumina reinforcement and obtained UPR/Al2O3 composites was performed by FTIR spectroscopy. Morphology was studied by scanning electron microscopy (SEM). The microhardness test was done using the Vikers method. Obtained results showed an increase of microhardness of UPR/Al2O3 w composites up to 66.4%, while the increase of microhardness of UPR/Al2O3 m composite was up to 52.3% compared to UPR matrix.Komercijalni aluminijum oksid u formi viskersa (Al2O3 w) i sintentizovane Al2O3 čestice proizvedene sol-gel tehnikom (Al2O3 m) korišćene su kao ojačanja nezasićenih poliestarskih smola (NZPE). Pri-premljeni su kompozitni materijali sa udelom ojačanja od 0,1 mas. %, 0,25 mas. %, 0,5 mas. %, 1,0 mas. %. i 2,5 mas. %. Strukturna analiza korišćenih ojačanja i dobijenih kompozita NZPE/Al2O3 izvršena je FTIR spektroskopijom. Morfologija korišćenih ojačanja ispitana je pomoću skenirajućeg elektronskog mikroskopa (SEM). Ispitivanje mikrotvrdoće urađeno je Vikersovom metodom. Dobijeni rezultati su pokazali da je povećanje mikrotvrdoće kod kompozita NZPE/Al2O3 w do 66,4% a kod kompozita NZPE/Al2O3 m do 52,3% u odnosu na čistu poliestarsku matricu NZPE

Innovative environmentally friendly technology for copper(II) hydroxide production

The innovative laboratory procedure for the synthesis of copper(II) hydroxide in the form of the aqueous suspension was developed. The reaction mechanism consists of the reaction between copper(II) sulphate pentahydrate and sodium carbonate by successive ion exchange of carbonate ions with the hydroxide ones in a multistep process. Production of copper(II) carbonate and sodium sulphate by reacting of copper(II) sulphate with sodium carbonate was followed by addition of sodium hydroxide solution whereby the product, copper(II) hydroxide, was obtained by releasing an equimolar amount of sodium carbonate. It was determined that, the equimolar reaction of copper(II) sulphate and sodium hydroxide lead to the maximal reactants exploitation. Sodium phosphate, formed in the final process stage by addition of 10% phosphoric acid solution, acted as a copper(II) hydroxide stabilizer. High yield of the product was obtained by optimizing the synthesis parameters: reaction time, molar ratio of reactants and the reaction temperature. The obtained product was formulated to obtain a commercial product, which is used as a fungicide and bactericide

Microvickers hardness determination of unsaturated polyester resins reinforced with alumina based reinforcement

Commercial alumina wiskers (Al2O3 w) and synthesized alumina particles via sol-gel technique (Al2O3 m) were used as reinforcement in unsaturated polyester resins (UPR). Composite materials with the addition of 0.1 wt. %, 0.25 wt. %, 0.5 wt. %, 1.0 wt. %. i 2.5 wt. % of alumina based particles were obtained. Structural analysis of used alumina reinforcement and obtained UPR/Al2O3 composites was performed by FTIR spectroscopy. Morphology was studied by scanning electron microscopy (SEM). The microhardness test was done using the Vikers method. Obtained results showed an increase of microhardness of UPR/Al2O3 w composites up to 66.4%, while the increase of microhardness of UPR/Al2O3 m composite was up to 52.3% compared to UPR matrix