Linseed oil-filled microcapsules containing drier and corrosion inhibitor - Their effects on self-healing capability of paints

Core-shell microcapsules of urea-resorcinol-formaldehyde shell and linseed oil (LO) core material as paint additives for self-healing coatings were prepared. The capsules contained LO either with or without Co-octoate as drier material and/or octadecylamine (ODA) as corrosion inhibitor. The microcapsules embedded in a commercial paint were applied on sandblasted mild steel sheets. After scratching the coated surface, the inhibition efficiency of core-shell microcapsule-containing coat, dipped into corrosive media, was followed visually and evaluated numerically by electrochemical impedance spectroscopy (EIS). In separate experiments, to optimize for the self-healing process, the composition of the core material, the effect of the drier and/or the inhibitor ODA on drying process of LO films were monitored by infrared spectroscopy. Pure LO needed 6-7 days to dry completely. The drying period could be shortened (to 5 h) via application of a dryer, but the addition of the corrosion inhibitor alone increased significantly the time needed for solifidication. To minimize the drying period we have found the proper combination of the ODA and the dryer of the LO. The EIS measurements, in accordance with the drying tests, resulted in the next order of self-healing ability: LO < LO(+ODA) < LO(+Co-octoate) < LO(+ODA+Co-octoate). (C) 2015 Published by Elsevier B.V

Coordination Chemistry and Sensing Properties Towards Anions and Metal Ions of a Simple Fluorescent Urea

The coordination and sensing properties towards anions and transition metal ions of the simple novel fluorescent urea 1-(2-aminophenyl)-3-(naphthalen-1)-yl)urea (L) were investigated in solution, and in the solid state. An electron donating amine group in the molecular skeleton of L decreased the acidity of the urea NHs that are usually deprotonated by basic anions and allowed for a good degree of affinity towards fluoride in DMSO-d6-0.5 %H2O. Moreover, the amine moiety acted as a further binding group for metal ions. Indeed, L was able to bind Zn2+ both in solution and in the solid state, and to respond to the presence of this metal ion in MeCN with an enhancement of the fluorescence emission. Although solution studies evidenced the formation of a 1 : 1 complex of L with Zn2+, complexes with a 2 : 1 ligand-to-metal stoichiometry were isolated in the solid state. DFT calculations helped to clarify the stability reasons behind these results

Continuous catalyst free production of biodiesel from agro industrial waste with green solvents

Dissertação para obtenção do Grau de Mestre em Engenharia Química e BioquímicaThe aim of this thesis consists in the study of the production of biodiesel via catalyst free direct transesterification of spent coffee ground oil with supercritical methanol in a continuous process. Supercritical methanol is passed through a packed bed reactor with the spent coffee grounds. Inside the reactor supercritical methanol extracts the triacylglycerols, which are immediately transesterified into fatty acid methyl esters. Therefore, the extraction and transesterification processes take in a single step. It was demonstrated that, at the optimal conditions of operation of 533 K, 10 MPa and solvent flow of 1 ml/min, the maximum yield for the total process was 83%. The effect of supercritical CO2 (ScCO2) as co-solvent was also studied. When using carbon dioxide as co-solvent at supercritical conditions, higher yields were obtained at milder temperature conditions. A maximum yield for the total process of 86% was obtained at 314 K for extraction of oil, 473 K for the reaction into FAME, 10MPa, solvent flow of 4.13 ml/min and a volume fraction of ScCO2 in the solvent feed of 27%

ICE System: Interruptible control expert system

The Interruptible Control Expert (ICE) System is based on an architecture designed to provide a strong foundation for real-time production rule expert systems. Three principles are adopted to guide the development of ICE. A practical delivery platform must be provided, no specialized hardware can be used to solve deficiencies in the software design. Knowledge of the environment and the rule-base is exploited to improve the performance of a delivered system. The third principle of ICE is to respond to the most critical event, at the expense of the more trivial tasks. Minimal time is spent on classifying the potential importance of environmental events with the majority of the time used for finding the responses. A feature of the system, derived from all three principles, is the lack of working memory. By using a priori information, a fixed amount of memory can be specified for the hardware platform. The absence of working memory removes the dangers of garbage collection during the continuous operation of the controller

Adsorption and desorption of gases in porous silicon

This research was undertaken to provide an understanding of the nature, origin and desorption mechanism of species found on the porous silicon (PS) surface and the changes that occur when PS is stored under varying conditions. The PS used in this work was produced from p-, high-resistivity FZ c-Si substrates.Three types of commonly used HF-based electrolytes were chosen for anodisation, under the same process conditions. With the resulting samples, temperature programmed desorption (TPD) coupled with mass spectrometry were used to identify species liberated at different temperatures. FTIR was also used to investigate the nature of surface species on PS and hence to infer how these give rise to the observed volatile products. After various modifications, the TPD system with the custom-made heating unit and the appropriate methodology were developed to suit the present work. Freshly anodised PS in the vacuum chamber at room temperatures gave somewhat enhanced peaks due to air components (0 ⁺, N₂⁺ and/or CO⁺, O₂⁺ and CO₂⁺) and, most significantly, an increase in F-containing species (e.g. F ⁺), derived from the electrolyte. On heating, the main desorbed species were found be hydrogen, silane, Si-Fx species, and Hx-Fx species. TPD spectra for hydrogen showed two peak maxima with a "hump". This implies two types of hydrogen environments; these were assigned as Si-H (lower temperature peak) and Si-H₂ (higher temperature peak) species on the PS surface. The temperature difference between the two peaks was similar (~100K) in all three cases. This shows that hydrogen desorption occurs similarly from PS prepared using the three different electrolytes. It also suggests that hydrogen adsorption during PS formation occurs analogously in the three electrolytes. Silane was observed to desorb at 575K. It is proposed that this comes from -SiH3 groups on the PS surface, possibly after reaction with sorbed water. A mechanism is suggested. In contrast, desorption of Si-Fx species was found to be sensitive to the nature of the electrolyte. The lower temperature peaks from the TPD experiments are assigned to H₂SiF₆ , SiF ₄ and perhaps H₂SiF₂ (by-products from anodisation) sorbed on PS. They are held relatively weakly by electrostatic and/or van der Waals forces. The higher temperature peak assigned to SiF₃ + may be explained in terms of migration of F atoms followed by Si-SiF₃ bond breakage. The various Hx-Fy products derive from species present in the HF electrolytes. To investigate changes in PS under typical storage conditions, samples were kept in (i) a blue wafer box, (ii) a screw-top white box and (iii) a similar box in a vacuum desiccator. The PS was then analysed by FTIR after various time intervals. After one month, only PS stored under condition (iii) was unchanged. The other samples showed evidence of oxidation, attributed to hydrolysis, fonnation of silanol (SiO-H) species, and back-bond oxidation of Si-Hx groups. Further ageing revealed inclusion of C-H species on PS. This work is a contribution to understanding of PS behaviour, and is relevant to its applications in electronic devices and sensors