Conventional benzoxazine resins, in spite of their excellent thermo-mechanical properties and good solvent resistance, suffer from high curing temperatures and limited self-healing/ reprocessability. In this frame, biosourced phenol (Phloretic acid), various diols (Dodecandiol/PEG200/Ethylene glycol), and amine (monoethanolamine) have been used in appropriate proportions to synthesize innovative benzoxazine precursors bearing exchangeable ester functions following a solventless method. They can be directly handled and used for coating applications without using any solvent. The overall synthesis was followed by Nuclear Magnetic Resonance and Fourier transform infrared spectroscopy (FT-IR). The reduced curing temperature, thermal stability, good thermo-mechanical performance, and ester bond exchange-ability system were demonstrated by Differential Scanning Calorimetry (DSC), thermogravimetric analysis (TGA), and Dynamic mechanical analysis (DMA stress relaxation testing), respectively. The elaborated resins were applied on etched aluminum 1050 without solvent and the corrosion resistance of the coatings was investigated by electrochemical impedance spectroscopy (EIS). The electrochemical results showed proper corrosion protection on aluminum substrates. The best result was obtained with Dodecandiol-based benzoxazine coating due to its longer aliphatic chain and hydrophobic property. Comparing this coating with an epoxy-based benchmark showed enhanced corrosion resistance for the benzoxazine after 50 days of immersion, making it an interesting candidate for future industrial use.

This article aims at improving the understanding of the corrosion mechanism of AZ31 magnesium alloys during a long period of immersion in an aqueous electrolyte. In particular, the influence of the starting pH of the electrolyte on the oxidation of AZ31 alloy and its evolution due to corrosion phenomena were investigated. Several electrolytes with different pH values containing or not chlorides were used. The electrochemical properties of the metal substrate in these electrolytes were studied as a function of immersion time by electrochemical impedance spectroscopy. The kinetics of the reactions were determined by potentiodynamic polarization as well as dihydrogen evolution measurements by eudiometry. All these tests were carried out while the sample surface and electrolyte volume remained constant. The corrosion products generated on the alloy surface were analyzed by X‐ray photoelectrons spectrometry. This study has shown that the evolution of the corrosion rate and the corrosion products depends greatly on the initial pH and the nature of the used electrolyte. Alkaline electrolyte leads to a passive protective layer that can be locally destroyed by chloride ions. For a neutral chloride electrolyte, the strong increase of the pH due to the magnesium corrosion is not able to form a protective layer by precipitation of corrosion products. The kinetic and the corrosion extent are affected by the pH changes.

An aqueous hybrid inorganic/organic sol-gel solution composed of tetraethylorthosilicate (TEOS), methyltriethoxysilane (MTES) and (3-glycidyloxypropyl)trimethoxysilane (GPTMS) was applied on ZnFe (14 wt.% Fe) electrodeposited on steel as a sacrificial layer. Two precursor contents were studied: 10 (SG10) and 30 % (SG30). First, the morphology and thickness of the films were assessed by Scanning Electron Microscopy (SEM) observations. They revealed the presence of micro-cracks in the films without alkaline surface preparation due to the pyramidal shape of the ZnFe deposit. Then, the corrosion resistance of the systems was determined by Electrochemical Impedance Spectroscopy (EIS) and Neutral Salt Spray (NSS) test. All results indicated an improvement in the corrosion resistance thanks to the presence of the SG films. However, the protection provided by the SG10 film did not permit to durably protect the ZnFe deposit. The combination of surface preparation and a SG30 film provided promising protection to the ZnFe deposit with an increase of the low-frequency modulus and a delay in corrosion product appearance during the NSS test.

In the context of protecting Mg-based nano-objects for potential hydrogen storage applications, the potential of C:H layer as a barrier polymer material deposited by the plasma-enhanced chemical vapor deposition process is examined. Corrosion tests reveal (a) good barrier properties of the C:H layer and (b) suggest an increase in the internal stress with the power dissipated in the plasma. The latter is attributed to an increase in the cross-linking density of the coatings accompanied by an increase in the stiffness as shown by nanoindentation measurements. Finally, for a given set of plasma parameters, Mg-based nanowires were successfully enrobed by the C:H coatings as evidenced by scanning electron microscopy measurements.

Introduction Antibiotic detection has become a major issue in many fields such as water analysis, food control, health, etc. Besides the immediate dangers, the spread of antibiotics everywhere provokes the phenomenon of bacterial resistance which, on the long run, will cause health issues. Indeed, the excessive use of antibiotics allows the bacteria to mutate and thus develop resistance, requiring the development of new compounds. This work aims to develop and characterize a sensing material to detect multiple antibiotics in liquid phase using various methods. The idea is to conceive low power sensors or even disposable sensors. Therefore, sensors should be low cost and compatible for mass production. The most interesting sensitive materials seem to be molecularly imprinted polymers (also called MIP) using conductive polymers [1],[2]. Synthesis of the MIP Polypyrrole (PPy) is chosen as conductive polymer to be molecularly imprinted. Pyrrole (Py) is used as the cross-linker and pyrrole-3-carboxylic acid as the functional monomer, to obtain chemical interactions between polymer and the target molecule (also called “template”). The synthesis is performed in-situ (also called bulk polymerization) in aqueous media by mixing the target molecule, the functional monomer and the cross-linker with the oxidizer, ammonium persulfate (APS), while pH value is set to around 2.2, well below the template’s pKa to allow better interactions between monomers and the template. While oxidative polymerization takes place, temperature is kept at 30 °C, for 2 hours. The polymer is deposited everywhere in the reactor, and also on the substrates used to get the sensor. The next step, so-called extraction, consists in removing the template from the polymer. It is performed by using a solution of methanol and HCl (9:1) wherein substrates are immersed for 2 hours [3]. Then, substrates are stored in PBS (phosphate buffered saline) solution before being tested. Non-Imprinted Polymers (NIP) are also synthetized following the same steps, except that the template is not present during the synthesis. Measurement methods Polymerization has been performed on various substrates allowing to use multiple sensing methods to explore as much path as possible. Up to now, sensors had been performed and tested on chemoresistive plastic IDE sensors to perform impedimetric measurements, on quartz crystal microbalance substrates to perform mass variation measurements and on glass slide to perform UV/VIS/NIR absorbance measurements (the ultimate goal is to use the sensing material on optical fibers), as shown on Fig.1. Results and Conclusions Sensors are tested in PBS 0.5x solution (half the usual concentration). After the extraction step carried out on the various substrates, detection is performed by adding the target antibiotic into the PBS solution. Fig. 2 shows impedance measurements and this parameter grows nearly linearly as soon as we add a dozen ppb of the antibiotic. Fig.3 shows that for the same measurement method, the NIP nearly doesn’t react when we add the template, which means that the imprinting is functional and significantly increases the performance of the sensor. Fig. 4 and Fig. 5 show the evolution of the NIR spectrum of the sensing layers after contact with the antibiotic, for the MIP ad NIP, respectively. This method exhibits some limitation with a saturation above 50 ppb. Fig.6 shows the mass evolution on a quartz microbalance of the sensitive layer in contact with the target antibiotic and an interferent with the same concentrations to show the sensor specificity. The response shown to the interferent is quite weak in comparison with the one corresponding to the target molecule. In conclusion, the sensors were found to be able to detect concentrations of approximately 15 ppb and are close to the detection limits of conventional methods (10 ppb). In addition, they have proven their specificity to the target molecule by showing no reaction when exposed to the usual interferents. We showed that the MIP is suitable for both impedimetric sensors as well as for optical sensors (optical fibers or dipsticks for instance). References [1] S. A.Piletsky, N. W.Turner, P. Laitenberger, Molecularly imprinted polymers in clinical diagnostics – future potential and existing problems, Medical Engineering & Physics , 28 (2006), 971-977. doi:10.1016/j.medengphy.2006.05.004 [2] M. Díaz-Bao, R. Barreiro, J. M. Miranda, A. Cepeda et P. Regal, Fast HPLC-MS/MS Method for Determining Penicillin Antibiotics in Infant Formulas Using Molecularly Imprinted Solid-Phase Extraction, Journal of Analytical Methods in Chemistry, 2015 (2015). doi: 10.1155/2015/959675 [3] J. L. Urraca, A. J. Hall, M. C. Moreno‐Bondi, B. Sellergren, A Stoichiometric Molecularly Imprinted Polymer for the Class‐Selective Recognition of Antibiotics in Aqueous Media, Angewandte Chemie, 118 (2006), 5282-5285. doi: 10.1002/ange.200601636 Figure 1

The effect of three different cerium salts (Ce(NO3)3·6H2O, CeCl3·7H2O and Ce(OOCCH3)3·5H2O) on the ring-opening polymerization (ROP) of a model diamine-based benzoxazine (4EP-pPDA) was investigated. With the incorporation of the cerium salts, the curing temperature of 4EP-pPDA is reduced substantially, and the glass transition temperatures of the resulting networks are increased significantly. The three cerium salts exhibit different catalytic activities, which were analyzed by FT-IR, NMR, and energy-dispersive X-ray (EDX). Ce(NO3)3·6H2O was found to exhibit the best catalytic effect, which seems to be related to its better dispersibility within 4EP-pPDA benzoxazine precursors.

To protect Al alloys from corrosion, standard procedures in the aerospace industry use chromium-based acid anodizing with subsequent post-treatment steps also containing hexavalent chromium (Cr(VI)) ions. However, environmental and health related concerns associated with Cr(VI) have encouraged the search for new surface treatments providing effective corrosion protection without the drawback of generating toxic residues. In this investigation, a hydrothermal treatment in aqueous solution with cerium ions is proposed as a post-treatment for tartaric-sulfuric acid (TSA) anodizing, and its effects on the AA2524-T3 alloy corrosion resistance investigated. The effect of Ce on the characteristics of the surface film formed, such as morphology and corrosion resistance, is investigated by scanning electron microscopy and electrochemical impedance spectroscopy (EIS). The results show that the hydrothermal treatment in solution containing Ce(III) ions presents a less stable behavior than the treatment in boiling water. However, the results of the EIS experiments show recovery of the protective properties of the system, indicating that some self-healing properties must be imparted to the system.

The potential of sebacic acid as a corrosion inhibitor for hot‐dip galvanized steel in 0.1 M NaCl solution has been investigated. Different concentrations of the organic acid have been tested in order to understand the inhibition mechanism of the compound. The electrochemical test revealed a competitive mechanism between the dissolution of the metal in the acidified solution and the inhibition provided by the dicarboxylic species. The formation of a whitish layer consisting of zinc carboxylates and corrosion products was proved by means of scanning electron microscopy (SEM) investigation combined with Fourier transform infrared (FT‐IR) analysis. A bidentate bridging coordination between the Zn(II) and the carboxylic species is suggested.

Plasma electrolytic oxidation (PEO) coatings were produced on AZ80 magnesium alloy in a solution containing silicates and phosphates and working at high current densities with short treatment times. The effect of a sealing treatment in boiling water on corrosion and mechanical properties of the coatings were investigated. Moreover, the corrosion mechanism of the samples with and without the sealing treatment was evaluated. The microstructure of the coatings was characterized with scanning electron microscope observation and X-ray diffraction analysis. The mechanical properties were evaluated with nanoindentation tests and the corrosion resistance was studied by potentiodynamic polarization, electrochemical impedance spectroscopy, and scanning vibrating electrode technique. The results showed that the sealing did not influence the microstructure and the mechanical properties of the samples and instead produced a remarkable increase in the corrosion resistance. The crevice corrosion, present in the sample without the sealing, was avoided with the treatment in boiling water.

The sol–gel coating method is considered to be simple and easy to implement to lead to organic/inorganic hybrid coatings. In addition, the application of thin films by this technique is inexpensive and applicable on large substrates without form restriction. In this context, thin sol–gel coatings based on a mixture of three alkoxysilanes and synthesized in purely aqueous phase with different thicknesses and with the presence or not of ZrO2 nanoparticles, were applied on metallic and glass substrates. After application and curing, the mechanical properties of sol–gel coatings were characterized by Berkovich nanoindentation with continuous stiffness measurement mode (CSM). The effective elastic moduli as well as the hardness values were estimated for each coating along the indentation depth and as a function of the substrate material and sol–gel characteristics. The effect of a annealing at higher temperature was also studied. Then, the failure modes of sol–gel coatings were investigated using both Berkovich nanoindentation and nanoscratch technique with a 5 µm radius spherical diamond tip. Careful microscopic observations of residual imprints and residual grooves both exhibit chipping in case of thick coating especially on glass substrate and no dramatic failure for thin coating applied on both substrates. It is shown in this work that the mechanical properties of the sol–gel and the mechanical stability of coatings on substrates are influenced dramatically by the presence of nanoparticles and the thermal treatment. Finally, interfacial fracture toughness of sol–gel coatings on substrate was estimated using analytical model from the literature and Ashby map based on experimental results was created using performance indices in order to proceed to sol–gel coating selection.

Phenol‐paraphenylenediamine (P‐pPDA) benzoxazines exhibit excellent barrier properties, adequate to protect aluminum alloys from corrosion, and constitute interesting candidates to replace chromate‐containing coatings in the aeronautical industry. For the successful application of P‐pPDA coatings, it is necessary to decrease the curing temperature to avoid the delamination of the coating while preserving the mechanical properties of the alloy, as well as the barrier properties of the coating. However, decreasing the curing temperature leads to less polymerized films, the extent of which requires a quantitative assessment.While the conversion rate of the polymerization reaction is commonly evaluated for bulk samples using differential scanning calorimetry (DSC), a tool for its evaluation in thin films is missing. Therefore, a new approach was developed for that matter using time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS). The relation between the SIMS data integrated from inside thin films and the DSC results obtained on bulk samples with the same curing cycle allowed to calibrate the SIMS data. With this preliminary calibration of the technique, the polymerization of P‐pPDA coatings can be locally determined, at the surface and along the depth of the coating, using dual‐beam depth profiling with large argon cluster beam sputtering.

The Ethylene-Propylene-Diene Monomer (EPDM) is a material used for the housing of the high voltage composite insulators. The stress conditions related to that outdoor exposure causes alteration of the material's properties. Several characterization techniques were used in this study for the evaluation of the thermal aging of the EPDM. The FTIR technique was used to evaluate the molecular behaviors of the material. The Carbonyl Index measurement was used to assess the oxidation rate of the material along the aging by means of FTIR spectroscopy. The crosslink density was measured using the solvent swell method. For the macroscopic characterization, the surface roughness of the aged samples was measured. This study showed that both crosslinking and oxidation were observed within the studied samples with a linear variation along the aging time. The correlation between the molecular and morphological properties was investigated. This study showed that for each structural scale a phenomenon of degradation is observed during the aging. The erosion of the material observed by the use of the surface roughness measurement has an impact on the oxidation of the material which was monitored by the use of the FTIR spectroscopy. Both of these measured parameters increase along the aging time. This increase is more important when the aging temperature became higher.

The mechanism of corrosion protection of zinc‐magnesium coatings on steel is investigated in this work in order to understand if each layer of the metallic coating is able to provide galvanic protection to the underlying layer and to the steel substrate. Thus, the electrochemical behavior of the metallic coating is studied as a function of the in‐depth structure and composition. The microstructure of each layer is analyzed using the scanning electron microscopy in combination with energy dispersive X‐ray spectroscopy (SEM/EDXS). The electrochemical characterization is carried out by means of electrochemical micro‐cell and scanning vibrating electrode technique (SVET). The corrosion protection mechanism of Zn‐Mg metallic coatings is based on the galvanic protection provided by the Zn‐Mg and Zn layers to the steel substrate. Preferential Mg dissolution in the metallic coating plays an important role in the protection mechanism. Local alkalinization at cathodic sites favors the precipitation of protective Mg‐rich oxides/hydroxides that reinforce the protective corrosion products and therefore could inhibit corrosion processes on the metallic coating and steel substrate.

In this study, carbon nanotubes (CNTs)/ZnO composites had been prepared using the sol-gel method and then incorporated into an epoxy resin for reinforcement of mechanical and electrical properties. Fourier Transform Infrared (FTIR), X-ray diffraction (XRD) Field Emission Scanning Electron Microscope (FE-SEM) analyses show that the ZnO nanoparticles deposited on CNTs were crystallized in a hexagonal wurtzite structure. Average particle size of ZnO deposited on the CNT was about 8 nm. The mechanical and dielectric properties of epoxy containing CNTs/ZnO were investigated in comparison to epoxy resin and epoxy resin containing only CNT or ZnO nanoparticles. The results indicated that tensile strength and elongation at break of the nanocomposite were substantially improved with the presence of CNTs/ZnO at the equal volume. The DSC analysis associate with the dielectric results shows that the behavior of epoxy/CNTs/ZnO is identical to epoxy/ZnO composite, and the CNTs is essential to the distributed arrangement of ZnO in the epoxy resin.

During the lifetime of a High Voltage composite insulator, the housing of that latter is exposed to stress conditions. Those exposures alter the insulating behavior of the insulator in term of Electrical field (E-field) distribution and, consequently, the leakage current flow. The assessment of that evolution is an important parameter to be considered during the design of the insulator in order to prevent additional stresses such as dry band arcing which is caused by the leakage current increase. In this paper, an attempt has been made to build a model based on the Finite Element Method (FEM) for the calculation of the E-field distribution around a composite insulator. This model was used to assess the impact of the aging of the housing material. A program was developed in order to minimize the effect of the aging of the housing. That optimization was done by modifying the construction parameters of the insulator.

A convenient and efficient approach is presented in this study for developing advanced thermosetting composite laminates reinforced or not with 0.5 wt% of pristine CNTs. A highly aromatic benzoxazine monomer was selected as the matrix for the preparation of carbon fiber composites due to its strong intrinsic affinities with CNTs. Fine CNT dispersion was achieved within the whole composite after fabric impregnation leading to a considerable increase of the glass transition temperature of about 50 degrees C. The resulting multiscale composite exibits an improved thermomechanical stability, up to 300 degrees C and its room temperature flexural strength is enhanced from 520 to 700 MPa. Moreover, the confinement of neat CNTs within the whole composite is also found to have a beneficial effect on the fire properties and the water sensitivity of the composite. These promising results highlight that when neat CNTs are able to develop strong interactions with the aromatic resin, the resulting system can provide a new and efficient way to design and improve the properties of composite laminates. (C) 2016 Elsevier Ltd. All rights reserved.

A novel biobased benzoxazine monomer containing additional allyl functionality was synthesized using a solventless approach from the reaction of a natural occuring phenol: chavicol, para-phenylene diamine and formaldehyde. The chemical structure of this functionalized benzoxazine monomer was confirmed by H-1 NMR and FTIR. Its polymerization was investigated and monitored by DSC showing two well defined exotherms allowing the selective ring-opening polymerization of benzoxazine functions and the preservation of the allyl functionality. The network crosslink density could be further increased via the controlled polymerization of allyl functionalities with a post-cure in order to adjust the thermo-mechanical properties. When both networks were polymerized, the thermoset presented an excellent thermo-mechanical stability with a T alpha higher than 350 degrees C as measured by DMTA. This exceptional behavior for a potentially biobased benzoxazine resin will allow the preparation of sustainable high performance biocomposite materials. (C) 2016 Elsevier Ltd. All rights reserved.

This work presents a scalable and solventless synthesis of two fully bio-based bis-benzoxazine resins derived from resorcinol, hydroquinone and furfurylamine. The structures of the two synthesized precursors have been studied by H-1 NMR and FTIR spectroscopies and SEC. The polymerization and degradation of the precursors have been investigated and monitored by DSC and TGA. The properties of the resulting polybenzoxazine networks were found to be dependent on the precursor molecular structure. In both cases, an excellent thermomechanical behavior associated with high charring ability were obtained which highlights the great potential of these fully bio-based resins as new matrices for the preparation of structural composites following a sustainable approach. (C) 2016 Elsevier Ltd. All rights reserved.