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Sunlight curable hybrid organic–inorganic methacrylic‐based coatings: analysis of the cure mechanism and functional properties
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An experimental ultraviolet (UV) polymerizable hybrid organic–inorganic protective coating, mainly intended for the surface protection of porous calcareous stone substrates, has been recently proposed and patented. The hybrid product evidenced an extraordinary hydrophobicity character, able to guarantee a high protection of the stone against water actions, as well as a high traspirability. Furthermore, it is able to equal the performance of commercial available coatings, with the important adjunctive advantage to be free solvent. The application of this product involves the use of a “dual curing” treatment, necessary to harden the coating applied on the substrate, representing this latter a technological limit. The dual curing treatment consists of 6 hr of exposure to a UV‐lamp plus 1 hr at 140°C in oven. In order to avoid this procedure, not easy to realize in situ, two different modifications of the composition of the hybrid product are proposed in this paper. The first one allows the photopolymerization of the hybrid coating only by sunlight exposure. The second one, even though requiring a UV exposure to photo‐polymerize the coating, does not need the subsequent thermal treatment at 140°C. Several experimental characterizations were performed on the newly developed hybrid products, in order to select an optimal composition for the formulations. The selected innovative products were, finally, applied on a calcareous stone substrate, typical of Apulia Region (Pietra Leccese, PL). Both coatings exhibit excellent water‐repellent action and a slight variation of the natural stone color. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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D. Frigione 《La Rivista del Nuovo Cimento (1969-1970)》1999,22(8):1-37
Conclusion In this paper we have examined various aspects regarding high-density operation in tokamaks and in particular the density
limit, the plasma detachment, the MARFE formation and the fuelling efficiency. As regarding the density limit, both experimental
findings and theoretical model indicate that the plasma current and the total input power are relevant in limiting the edge
density that can be sustained in a tokamak discharge: radiation losses and SOL momentum and energy conservation are the underlying
mechanisms. In the latest divertor experiments, operating in the detached regime, the influence of the input power seems to
vanish or even disappear. Edge phenomena such as plasma detachment, occurring beyond a density threshold that can be lowered
by means of impurity injection, can lead to the almost complete exhausting of the heating power by radiation which is greatly
helpful for the design of the divertor plates. The compatibility of H-mode operation with this regime is still under investigation.
The MARFE phenomenon, sometimes precursor of a major disruption, is now understood in terms of a radiation induced thermal
instability. Finally, experiments performed in order to investigate the fuelling efficiency of the gas puffing technique have
shown that at high density this technique becomes rather inefficient, thus indicating that pellet injection still remains
an essential requirement to fuel the reactor plasma. The drop of the fuelling efficiency of gas-puffing at high density can
be accounted for by collision phenomena taking place in the SOL. 相似文献
3.
A hyperbranched polymer (HBP), based on a highly branched polyester, was added to a trifunctional triglycidyl-p-aminophenol (TGAP) epoxy resin as a possible route to increase the toughness of the resin. Different amounts of the HBP, up to 26.5% wt. of resin, were dispersed in the TGAP resin. The rheological behavior of the formulations produced was studied as function of the shear rate and the filler content using a cone and plate rheometer. The rheological behavior of the TGAP resin, initially Newtonian, was modified displaying a pseudo-plastic trend when the hyperbranched polymer was added. An increase in the viscosity of the resin was observed with increasing volume fraction of the filler. The Cross equation was used to predict the viscosity of each formulation as a function of the shear rate. A novel procedure was developed to predict the viscosity of each mixture as a function of the filler volume fraction. This could be employed to provide quantitative information on the filler volume fraction in epoxy/HBP systems, necessary to achieve the characteristic viscosity values corresponding to the typical shear rates for a specific processing technology. 相似文献
4.
Influence of nitrogen speciation on the TDN measurement in fresh waters by high temperature catalytic oxidation and persulfate digestion 总被引:1,自引:0,他引:1
Marco Minella Gabriele A. Tartari Michela Rogora Mattia Frigione Davide Vione Claudio Minero 《International journal of environmental analytical chemistry》2016,96(5):474-489
Analytical methodologies for the determination of total dissolved nitrogen (TDN) in waters are based on a conversion step able to transform selectively all the nitrogen species into a compound that is then quantified. A crucial requirement to meet accuracy is the quantitative recovery of all organic and inorganic nitrogen species during the conversion step. In this work, the N recoveries of two widely employed methodologies that use different conversion steps (high temperature catalytic oxidation (HTCO) and persulfate digestion (PD)) were assessed on a set of organic nitrogen compounds, representative of the structures of both dissolved organic matter (DOM) and anthropogenic contaminants. Low recoveries are due to poor selectivity during the conversion step, with the formation of nitrogen compounds other than nitrogen oxide (HTCO) and nitrate (PD). The results show that in many instances the TDN measurements give systematically low results depending on N speciation. PD could give lower results than HTCO even for samples containing only DOM of biological origin. In particular (i) low N recovery was always observed with compounds having two or more contiguous N atoms; (ii) the HTCO method is very effective for TDN quantification in the presence of s-triazine rings while PD method did not yield satisfactory N recovery; (iii) a full N recovery was observed with compounds having amido or amino groups or nitrogen atoms in imidazole, indole and pyrimidine rings; and (iv) the N recoveries for purine derivatives are almost complete with HTCO, but give systematically low results by PD.Finally, the estimation of dissolved organic nitrogen (DON) fluxes and pools from TDN measurements can be affected by uncertainties larger than previously thought as a consequence of (i) the lower N recovery for some nitrogen compounds and (ii) the differences in the N recovery as a function of the adopted analytical methods. 相似文献
5.
Carola Esposito Corcione Giulio Malucelli Mariaenrica Frigione Alfonso Maffezzoli 《Polymer Testing》2009,28(2):157-164
The effect of the presence of a hyperbranched OH-functionalized polymer (HBP) on the kinetics of cationic photopolymerization of an epoxy system was investigated employing two complementary techniques, photo-DSC and real-time FT-IR spectroscopy.Lower rates of cross-linking reactions and higher conversion degrees were obtained in photo-DSC experiments with respect to real-time FT-IR spectroscopy. A limited amount (10% wt) of HBP influenced to a certain extent the cure kinetics of the epoxy resin followed by RT-IR; a final conversion of epoxy groups equal to 100% was achieved by increasing the content up to 20% wt The addition of 10% wt of HBP leaves the cure kinetics of the CE resin studied by p-DSC almost unchanged. By increasing the HBP content, a slightly lower reaction rate is observed at lower reaction times. The presence of the HBP produced a continuous decrease of the Tg of the UV-cured epoxy resin but only modest reductions in its thermo-oxidative stability. 相似文献
6.
JET quasistationary internal-transport-barrier operation with active control of the pressure profile
Crisanti F Litaudon X Mailloux J Mazon D Barbato E Baranov Y Bécoulet A Bécoulet M Challis CD Conway GD Dux R Eriksson LG Esposito B Frigione D Hennequin P Giroud C Hawkes N Huysmans G Imbeaux F Joffrin E Lomas P Lotte P Maget P Mantsinen M Moreau D Rimini F Riva M Sarazin Y Tresset G Tuccillo AA Zastrow KD 《Physical review letters》2002,88(14):145004
Quasistationary operation has been achieved on the Joint European Torus tokamak in internal-transport-barrier (ITB) scenarios, with the discharge time limited only by plant constraints. Full current drive was obtained over all the high performance phase by using lower hybrid current drive. For the first time feedback control on the total pressure and on the electron temperature profile was implemented by using, respectively, the neutral beams and the ion-cyclotron waves. Although impurity accumulation could be a problem in steady state ITBs, these experiments bring some elements to answer to it. 相似文献
7.
Mariaenrica Frigione Mariateresa Lettieri 《Journal of Polymer Science.Polymer Physics》2008,46(13):1320-1336
The absorption/desorption behavior of a commercial cold‐cured bisphenolic epoxy resin, subjected to different treatments prior to exposure to water, was analyzed. The epoxy system has been already used as both matrix and adhesive for the manufacture and application, respectively, of fiber reinforced polymers composites employed for rehabilitation procedures. The effects of different curing, conditioning, and storing conditions on the water absorption/desorption process taking place in the cured resin were evaluated. The different conditioning procedures used to dry the specimens before their exposure to water caused a different extent of physical aging and of curing on each system, influencing the amount and the rate of diffusion of the water molecules inside the specimens. Moreover, if the specimens are subjected to thermohygrometric cycles prior to immersion in water, the rate of diffusion and the amount of water also depends on the presence of water molecules inside the cured resins not easy to remove by any drying treatment. During all the hygrometric treatments performed, a deaging process took place. The kinetic of this deaging process for the not‐fully cured systems depends on the additional crosslinking taking place in the samples. The different procedures used to condition the specimens also affect the variations in glass transition temperature (Tg) of the cured systems during and after immersion in water. Finally, the different drying procedures employed proved to be not equally appropriate for cold‐cured epoxy resins. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1320–1336, 2008 相似文献
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