The effect of Tinuvin derivatives as an ultraviolet (UV) stabilizer on EPDM rubber

Ethylene-propylene-diene monomer (EPDM) is one of the most widely used synthetic rubbers, especially in the automotive industry. Despite its many benefits, the chief weakness of EPDM has been the color change occurring in its products due to ultraviolet (UV) rays. It is recognized that UV energy causes the dissociation of bonds (mostly C-C and C-H) in EPDM materials as well as cracks and color changes on the surface. The aim of this study was to investigate the effect of the Tinuvin derivatives widely used as UV stabilizers in the plastics industry on EPDM rubber. The EPDM rubber plates were prepared by adding Tinuvin-P, Tinuvin-213 and Tinuvin-234 as UV absorbers (UVAs) and Tinuvin-123 as hindered amine light stabilizer (HALS) material at a ratio of 1.0 phr (parts per hundred parts of rubber) to an available EPDM formula. The effects of the Tinuvin derivatives were investigated by the internationally recognized Florida outdoor aging test. The surfaces of the EPDM plates were visually scrutinized and surface morphological changes were examined via scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and Fourier transform infrared (FTIR) spectrometry analyses. The results obtained showed that, unlike in the plastic industry, not all Tinuvin derivatives could be used as UV stabilizers for EPDM products. Of all the tested Tinuvin derivatives, the Tinuvin-123 compound was the most effective, indicating it to be suitable for use as a protective UV stabilizer for EPDM rubber applications

The effect of caffeine molecule on the physico-chemical properties of blended cement

Caffeine is a nontoxic and eco-friendly natural molecule used in the food industry as well as a corrosion inhibitor in various corrosive media. However, its behavior and performance as an additive in the construction industry has not been explored. This paper investigates the effect of caffeine as an additive on strength, water demands, setting time and hydration mechanism of cement. In the first instance, the water demand, volume expansion and setting time of cement pastes, incorporating 0, 25, 50 and 75 ppm of caffeine were determined. In the second section, the rate of hydration and cement pastes' products were conducted by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermal analysis and scanning electron microscope (SEM) at 28 days. Finally, the cement mortars' compressive strengths were determined at 2, 7 and 28 days intervals. Consequently, mortars containing 75 ppm caffeine registered higher strength than the pure cement mortars due to high quantities of primary C-S-H gel, chemically bound water, compact structure at 28 days. Furthermore, by result of analysis and experiments, it was determined that caffeine had no negative effect on cement. (C) 2020 Elsevier Ltd. All rights reserved.Duzce University Research FundDuzce University [2019.06.05.1036]; Nuh Cement Plant executivesThe authors would like to thank the financial support from Duzce University Research Fund (Project Code Number: 2019.06.05.1036) and Nuh Cement Plant executives and the staff for their invaluable contributions on this study.WOS:0005393861000742-s2.0-8508411210

The effect of zeolite and diatomite on the corrosion of reinforcement steel in 1 M HCl solution

The greatest disadvantage of reinforced concrete structures is the corrosion occurring in the reinforcement which, over time, causes a reduction in the reinforcement-concrete adherence and eventual sectional loss. The purpose of this study was to reveal the corrosion mechanism of ribbed reinforcement inside additive-free (reference), 20% zeolite-doped and 20% diatomite-doped concrete samples after exposure to 1 M HCl over 240 days. Electrochemical impedance spectroscopy (EIS) measurements were made every 10 days. Consequently, it was determined that the 20% zeolite-doped concrete samples had higher concrete and reinforcement resistance compared to the 20% diatomite-doped and the reference concrete, i.e. they exhibited less corrosion

Corrosion inhibition of reinforcement steel in mixture water by caffeine and L-arginine

Many additives are preferred to extend the usage of concrete constructions in order to increase durability. These compounds have to be non-poisonous and have no undesirable consequences on the environs. Out of all these concerns, amino acids are mainly used in food and drug industries as well as safe corrosion inhibitors in a number of acid solutions. Here, the corrosion inhibition efficacy of optimum concentration (50 ppm) of caffeine and L-arginine has been investigated for reinforcement steel in mixture water (MW) environment. This was performed for a duration of 2 h, 7, 28, 56 and 90 d using electrochemical impedance spectroscopy (EIS), dynamic EIS (DEIS), and potentiodynamic polarization (PDP) techniques. The surface of specimens was also investigated by atomic force microscopy (AFM), optical profilometer (OP) and scanning electron microscopy (SEM). DEIS results indicate that selected inhibitors protected reinforcement steel approximately up to 62% against corrosion till 7 d, then the effectiveness of the protection decreased to 30% on 90th day. It was also observed that L-arginine showed better inhibition efficiency than caffeine.Duzce University Research FundDuzce University [2019.06.05.1036]The authors acknowledge the financial support provided by the Duzce University Research Fund (Project No: 2019.06.05.1036). The authors also thank Dr. Marziya Rizvi (ORCID ID: 0000-0001-8928-529X) for his assistance in the interpretation of the EIS measurements. Africa Centre of Excellence in Future Energies and Electrochemical System, Federal University of Technology, Owerri, Nigeria is acknowledged for their contribution to this study.WOS:0006505062000012-s2.0-8510625807

Corrosion behavior of dual phase 600 and 800 steels in 3.5wt.% NaCl environment

Dual phase (DP) steels have a great deal of importance in the automotive industry. These steels are used to fabricate structural parts of vehicles with the goal of passenger safety. In this study, the corrosion properties of DP 600 and 800 steel in 3.5wt.% NaCl environment were evaluated using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), and weight loss methods. Although the samples were quite similar to each other in their composition, it was observed that the very small differences changed the corrosion resistance property. For this reason, the calculated charge transfer resistance (R-ct) of the DP-800 in the 3.5wt.% NaCl environment was 51% greater than that of the DP-600 sample. This finding was confirmed by using weight loss, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), atomic force microscopy (AFM), and optical profilometer (OP) analysis.Duzce University Research FundDuzce University [2016.06.05.457]For this work, the authors gratefully acknowledge the financial support provided by the Duzce University Research Fund [Project No: 2016.06.05.457].WOS:0004971361000012-s2.0-8507512935

Corrosion Protection of Aluminum Alloy AA7020 in NaCl Solution by Hybrid Sol-Gel Coatings

In this study, two different hybrid sols as tetraethyl orthosilicate/(3-Glycidyloxypropyl) trimethoxysilane (TEOS/GPTMS) and tetrapropyl orthotitanate/(3-Glycidyloxypropyl) trimethoxysilane (TPOT/GPTMS) were prepared and Aluminum AA7020 alloy was coated with these sols by the dip-coating method. Corrosion behavior of coated samples in 3.5% NaCl solution was investigated using potentiodynamic polarization (Tp) and electrochemical impedance spectroscopy (EIS) methods. The same electrochemical test and analysis procedures were applied to an uncoated AA7020 sample in order to the investigate corrosion protective perfomance of TEOS/GPTMS and TPOT/GPTMS coatings in 3.5% NaCl solution. Morphological analyses of the coated and uncoated AA7020 samples were made before and after corrosion test measurements via Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Spectrometry (EDS). The results obtained from EIS and Tp measurements for the coated and uncoated specimens were reviewed for the corrosion protection activities of the sol-gels coating. TEOS/GPTMS and TPOT/GPTMS sol-gel coatings were found to have high protection effect for the corrosion of AA7020 alloy in a 3.5% NaCl medium

Inhibition effect ofCynara cardunculusleaf extract on corrosion of St37 steel immersed in seawater with and without bleach solution

The inhibition performance of an aqueous extract ofCynara cardunculusleaves on the corrosion of St37 steel immersed in seawater and seawater with bleach was investigated using weight loss measurements, electrochemical methods, and surface characterization techniques. It was found that the extract components acted primarily as a mixed-type inhibitor, and inhibition efficiency increased with increasing inhibitor concentration. Electrochemical impedance spectroscopy (EIS) and dynamic electrochemical impedance spectroscopy (DEIS) confirmed the formation of a protective layer on the metallic surface in both solutions. The adsorption of inhibiting molecules conformed to the Langmuir isotherm model. The thermodynamic parameter values indicated that chemisorption constituted the major contribution to the adsorption process. This result was corroborated by scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) analyses. The significant inhibition effect can be related to the large amount of phenolic compounds in the CC aqueous extract as revealed by the Fourier-transform infrared (FTIR) spectrum.WOS:0005419561000012-s2.0-8508652088

Corrosion inhibition performance of dwarf palm andCynara cardunculusleaves extract for St37 steel in 15% H2SO4: a comparative study

The inhibition effect of extracts obtained from the commercially insignificant, perennial and overgrowing plants in Tunisia such as Dwarf palm (DP) andCynara cardunculus(CC) plants leaves against St37 steel corrosion in 15% H(2)SO(4)has been investigated with weight loss experiments (WL) and classical electrochemical methods. The investigations were conducted at the various concentrations of studied extracts, experiment temperature and time. The obtained results were compared with electrochemical impedance spectroscopy (EIS), dynamic electrochemical impedance spectroscopy (DEIS) and surface imaging method outcomes. The results showed that DP and CC extracts exhibit good corrosion inhibitor for St37 steel in 15% H(2)SO(4)solution. From all applied methods, DP extracts approximately showed better inhibition efficiency than CC. The adsorption of the inhibitors was found to obey the Langmuir adsorption isotherm. Results of infrared spectroscopy (FTIR) and physical electronics spectrometry (XPS) analysis strengthen the authenticity of other experimental results by proving that the extract molecules have bonded with the surface of the St37 steel.Duzce University Research FundDuzce University [2018.06.05.817]; Turkiye Burslari [19IN001804]For this work, the authors gratefully acknowledge the financial support provided by the Duzce University Research Fund [Project No: 2018.06.05.817]. One of the authors, Marziya Rizvi, thankfully acknowledges financial support provided by Turkiye Burslari [19IN001804] for this research.WOS:0005710976000012-s2.0-8509116761