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- ArtículoAcceso AbiertoFormulation and testing of a water-borne primer containing chestnut tannin(1998) Pardini, Oscar Ricardo; Amalvy, Javier Ignacio; Romagnoli, Roberto; Vetere, VicenteIn this work an aqueous primer containing chestnut tannin and phosphoric acid was developed and its anticorrosive properties assessed by different conventional tests. Treated Steel ponéis coated with an anticorrosive paint and a topcoat were subjected to the salí spray test, humidity chamber, mechanical tests (adhesión and flexibility) and electrochemical tests (corrosión potential, ionic resistance and polarization resistance). Electrochemical tests were done employing only ponéis primed with the primer. The binder employed in this research was prepared in the laboratory by emulsión polymerization of acrylic monomers. It was found that the tested formulation protected Steel against corrosión incorporating corrosión producís to the film as ferric tannates and avoiding oxide formation. Undercutting rusting was not significant and the scratch line stood free from oxides. The good stability of the binder in low pH media and the interaction of the binder with the substrate are decisive factors in the performance of this aqueous pretreatment system.
- ArtículoAcceso AbiertoManufacture and testing of water-based tannic pretreatments(1998) Giúdice, Carlos A.; Benítez, Juan C.; Tonello, M. L.The anticorrosive efficiency of the different coating systems depends to a great extent on the initial State of the metallic surface, since the best paints do not insure a lengthy protection when they are applied over a structure that is not adequately prepared In consequence, at present the treatment of the corroded surfaces continúes being a great challenge in spite of the modem existing methods, specially when the conditions do very expensive the total removal of oxides or is not practicable by diverse motives. In a previous work, the purification and the characterisation of tannins extracted from the heartwood of quebracho (Schinopsis sp.) were performed particularly with the objective ofknowing some inherent properties of the reaction between the tannins and the iron oxides. In the present work; severa1 water-based tarmic pretreatments acidified with orthophosphoric acid were formulated and manufactured at laboratory scale; results of tests carried out allowed to conclude that the application of the quoted tannic Solutions on a substratum with a mechanical preparation insufftcient to eliminóte the totality of the producís of corrosión, increased the useful Ufe of the applied coating system, delaying oxidation and in consequence the deterioration of the subsequent paint films.
- ArtículoAcceso AbiertoStudies on biofouling at Mar del Plata harbor: monthly settlement of calcareous species along a year(1998) Pérez, M. C.; García, M. T.; Stupak, Mirta E.Monthly settlement of calcareous species was followed in Mar del Plata harbor (Argentina) along a year. Large number of calcareous organisms recruited onto ceramic ponéis. Balanus amphitrite and Hydroides elegans were the most representative species settled on the primary space. Other bamacles, B. glándula + B improvisus followed in importance, but the number of recruits per panel was always low. All of them were measured and total occupied oreas estimated The species showéd different settlement cycles, different preferences by both depth levels and surface texture. The máximum peak of density for B. glándula + B improvisus was in December, for B amphitrite in February and for Hydroides elegans in March. Virtually no settlement took place during colder months (June-September). Bamacles preferred to settle on the back side of the panels, with grooves and pits, while serpulids showed no texture preferences. In relation with depth all species preferred to colonize the three deepest levels. Data corresponding to growth rotes indicated a rapid development during warmer months.
- ArtículoAcceso AbiertoThe use of potymerisable surfactants in emulsión copolymerization for coatings applications(1998) Amalvy, Javier Ignacio; Unzué, M. J.; Schoonbrood, H. A. S.; Asua, J. M.In this paper results obtained in high solids contení emulsión copolymerizations using polymerizable surfactcmts (surfmers) have been reviewed On the basis of the interpretation of the behavior of the surfmers (the conversión vs. time and their performance in stability tests and film properties), an optimal surfmer behavior has been defined, which means that all the added surfmer groups end up on the particle surface rather than being buried, which leads to inferior látex stability. One of the strategies that have been proposed to achieve this has been applied to prepare a well-defined styrene-butyl acrylate látex of which film can be easily be casi. Its properties in terms of mechanical stability, film water absorption, and film surfactant exhudation have been assessed and compared with these of a similar látex with sodiicm dodecyl sulfate. Other comonomer Systems have been studied as well with the maleic surfmer. In these Systems the surfmer behavior was less “optimum ”. For these lotices both mechanical stability and water absorption was assessed
- ArtículoAcceso AbiertoConcurrent solution and adsorption of hydrocarbons in gas chromatographic columns packed with different loadings of 3- methylsydnone on chromosorb P(1998) Castells, R. C.; Romero, L. M.; Nardillo, A. M.Thermodynamic properties of solution in 3-methylsydnone (3MS) and of adsorption at the nitrogen/3MS interface were gas chromatographically measured for a graup of fifteen hydrocarbons at infinite dilution conditions. Retention voluntes were measured at five temperatures within the range 37-52°C in six columns containing different loadings of 3MS on Chromosorb P AW. Partition and adsorption coejficients were calculated and from their temperature dependence the corresponding enthalpies were obtained, although with considerable error; infinite dilution activity coejficients of the hydrocarbons in the bulk and in the surface phases demonstrated an strong correlation. Bulk activity coefficients in 3MS were very much smaller than those previously measured for the same solutes in formamide (FA) and in ethyleneglycol (EG), and were also smaller than what could be predicted on account of 3MS cohesive energy density as estimated from the quotient a/v13 (cr. surface tensión; v: molar volume). There was not such a large difference between the surface activity coefficients in the three solvents; furthermore, the quotients (surface activity coefficient/bulk activity coefficient) for a given solute in 3MS were twice as large as in FA and about three times larger than in EG. These results make evident the difficulties inherent in the prediction of surface phase properties from those in the bulk, and casi doubts on the pertinency of employing the surface tensión to compare cohesive energy densities of polar solvents with important Chemical dijferences.
- ArtículoAcceso AbiertoSteel corrosión protection by means of alkyd paints pigmented with calcium acid phosphate(1998) del Amo, Beatriz; Romagnoli, Roberto; Vetere, VicenteThe use of classic anticorrosive pigments is beirtg more and more restricted by increasing environmental concems; they are gradually replaced by zinc phosphate and related compounds. Other anticorrosive pigments such as surface exchanged silicas were also proposed The object of this research is to study the anticorrosive properties of calcium acid phosphate as inhibitive pigment introducing a careful selection of complementary pigments in order to achieve an efficient anticorrosive protection. Several paints were prepared and tested through accelerated and electrochemical tests. The nature of the passive film was also studied. Paints containing zinc oxide and calcium carbonate (50/50) showed the best performance and a higher resistance in the salí spray test. Zinc oxide and calcium carbonate decreased film permeability and improved Steel passivation The passive film was composed by a ferric oxyhydroxide film whose pores became plugged by ferric phosphate.
- ArtículoAcceso AbiertoTin tannates and iron tannates in corrosion-inhibiting coatings(1998) Giúdice, Carlos A.; Benítez, Juan C.; Tonello, M. L.The efficiency of the coating systems in the protection of metallic substraía depends fundamentally, in relation with formulation variables, on the type and contení of corrosion-inhibitive pigment, the characteristics of the film forming material and the pigment / binder ratio in volume. Conceming the pigment, there is not doubt that the use of some inhibitors in anticorrosive paints is actually an important source generating toxicity problems both for the worker andfor the environment. This problem is extended to the applicator and álso to the removal operation of oíd coatings. In this research tin tcamates and iron tannates were employed as inhibitive pigments in anticorrosive paints. The mentioned metallic tannates were prepared on laboratory scale under controlled operative conditions, carrying out the reaction between the metallic ions and the polyphenolic groups of condensed tannins extracted from “quebracho ” heartwood (Schinopsis sp.).
- ArtículoAcceso AbiertoRetention in multistep programmed-temperature gas chromatography and flow control: linear head pressure programs(1998) González, F. R.; Nardillo, A. M.A comparative study of retention in different systems of flow control, that provide linear dependence with temperature of column’s head pressure, is performed by numerical simulation considering multistep (or multiramp) PTGC as the mosí general situation. Calculation algorithms for each flow control mode are developed on the basis of general retention equation and the only additional hypothesis that certain geometric parameters of the column remain practically constant along the program. Procedieres are individually contrasted with experimenta prior to application. The comparative view indicates that simple correlations ccmnot be obtained between retention times and temperatures in two different pressure Controls or pressure programs. It seems that numerical procedures are unavoidable when it is required the conversión of retention data from one chromatographic system to another with the same stationary phase.
- ArtículoAcceso AbiertoSEM study of intermetallic phases growth in a hot-dip galvanizing process(1998) Seré, Pablo Ricardo; Culcasi, José Daniel; Elsner, Cecilia Inés; Di Sarli, Alejandro RamónThe influence of both the cooling rate and the base Steel roughness upon the Al-rich phase was análized For this, Steel sheets were coated in a simulator of the hot-dip galvanized process working at 470 ºC up to reaching an average roughness valué of 1.30 or 0.90 pan; besides, either an air or water spray flow was used in order to obtain cooling rotes between 7 and 22 ºC s-1, respectively. The galvanized píate surfaces were characterized by means of SEM and XRD analysis. From the experimental results the following conclusions could be drawn: a) the Al-rich phase growths as an intermetallic (AlsFez), that crystallizes forming an orthorombic lattice in which increasing cooling rotes do not change the morphology but stop the growing of the crystals, and b) an increase of the Steel roughness makes that outburst structures but not the Al-rich phase develops at the bottom of pits.
- ArtículoAcceso AbiertoExtraction and characterisation of quebracho (Schinopsis sp.) tannins(1998) Tonello, M. L.; Giúdice, Carlos A.; Benítez, Juan C.Vegetables tarmins are organic substances; when considering the great number of different tarmins, it is possible to State certain properties which are common to all of them such as: a high molecular weight, causing colloidal Solutions in which the particles of tarmins are present in all forms of dispersions; a great number of free hydroxy phenolic groups, which are mainly responsable for the solubility of tannins in water; with few exceptions, all tarmins are amorphous and no crystalline; a different degree of acidity resultant from the polarity of the hydroxy phenolic groups which in some cases is enhanced by free carboxyl groups; tarmins formed by esterification of carboxyl groups usually exhibit a higher acidity than those made by condensation or polymerisation of components free from carboxyl groups; formation of intense precipitates in the presence of soluble iron (III) salís, etc. This last property of the tarmins, that is the capacity of forming chelates with the hexahydrated iron (III) ion, could be employed efficiently to modify the kinetic of oxidation of iron and Steel substraía. In this paper, the extraction, the purification, the concentration and the characterisation of tannins obtained from quebracho (Schinopsis sp.) were performed, particularly with the objective of knowing some inherent properties to the reaction between the tarmins and the iron.
- ArtículoAcceso AbiertoPhosphorus-based intumescent coatings(1998) Benítez, Juan C.; Giúdice, Carlos A.Fire is an energetic manifestation which carnes undesirable consequences due to the problems that it originates. The conflagration is a disagreeable fací produced by fire. The main objective of a fireproofing treatment is to make a material hardly flammáble or autoextinguishable. An ejficient fireproofing effect interrupts the combustión in one or more stadiums, leading the process to end in a reasonable period (preferably before ignition occurs). Intumescent coatings, as a means of passive protection against firet perform a fundamental role in this matter. Dry films of these paints, submitted to fíame action, softens in a first stage and then swells due to an intemal and partial loosing of non combustible gases, reaching up to 200 times of its original thickness. The charred coat, an incombustible spongy mass, protects the painted material’ delays the temperature increase and avoids the access of air, and so the combustión. By means of intumescent coatings, different materials such as paper, wood, pasteboard, plastics, metáis, etc. can be protected The objective of this paper was to study the influence of some formulation variables of phosphorus-based intumescent coatings, formulated and manufactured for this experiment. Chlorinated rubber coatings based on ammonium polyphosphate, pentaerythritol, melamine, 42 % chlorinatedparaffin and an endothermic filler showed very high performance after ageing.
- ArtículoAcceso AbiertoInfluence of differences between sample and mobile phase viscosities on the shape of chromatographic elution profiles(1998) Castells, R. C.; Castells, Cecilia Beatriz; Castillo, M. A.The injection of samples whose viscosities are appreciably different from íhat of the motile phase can result in highly distorted elution profiles, showing severai maxima. The distortions are produced at the rear of the band when the viscosity of the sample solvent is higher than that of the motile phase. It is shown that the distortion of the peaks produced on injecting arbutin in columns of aminopropyl silica, using water as mobile phase and mixtures of 2-propanol and water as the sample solvent, grows in importance when the sample size increases, when the viscosity of the sample solvent increases and when the flow rate is decreased On the other side distortions at the band front are observed when arbutin dissolved in water or in acetonitrile + water mixtures is injected in a 2-propanol-water (50:50) mobile phase of higher viscosity. These trends are coincident with the predictions of a hydrodynamic instability criterion postulated several years ago and up to now almost entirely ignored in chromatography, except in relation with size exclusión chromatography.
- ArtículoAcceso AbiertoThe performance of zinc molybdenum phosphate in anticorrosive paints by accelerated and electrochemical tests(1998) del Amo, Beatriz; Romagnoli, Roberto; Vetere, VicenteRed lead and zinc chromates are doubtless efficient pigments to protect metáis against corrosión. Their use in paints formulation is being restricted due to their deleterious action. Zinc phosphate wasfirstly suggested to replace toxic chromates. However, data on their anticorrosive properties are not conclusive; so, a second generation of phosphate pigments, including zinc molybdenum phosphate, was developed In this paper, the anticorrosive behavior of micronized zinc molybdenum phosphate in paints with 30% of the pigment by volume and a PVC/CPVC ratio 0.8, formulated with different binders (alkyd, vinyl, chlorinated rubber and epoxy resins), was assessed by accelerated (salt spray cábinet and accelerated weathering) and electrochemical tests. Epoxy and chlorinated rubber paints showed the best anticorrosive performance. The inhibitive action of zinc molybdenum phosphate was confirmed Good correlation has been obtained between salt spray and electrochemical tests.
- ArtículoAcceso AbiertoTheoretical and practical aspects of flow control in programmed-temperature gas chromatography(1998) González, F. R.; Nardillo, A. M.Behavior pattems for the temperature dependence of cohann head pressure and outlet volumetric flow rote are analyzed for some particular configurations of chromatograph's flow control system. Cuantitative prediction of this behavior, and specially it’s effect on gas hold up time, is evaluated the attention is centered on the application to PTGC retention simulation.
- ArtículoAcceso AbiertoComunidades incrustantes de áreas costeras naturales del sur de la Provincia de Buenos Aires (Argentina)(1998) Bastida, Ricardo; Martin, J. P.; Ieno. E.This work deais with the study of marine fouling communities of two Coastal localities of Buenos Aires Province. Sampling programme was carried out using artificial sampling substrates which were placed vertically on the intertidal and subtidal zone of Reta and Monte Hermoso shores. Both localities showed the dominance of the small mussel Brachidontes rodriguezi. Density of this species decreases towards the subtidal levels, while associated fauna density fluctuates with increasing depth. The studied localities show dijferences in some of their specific components and differ notably from fouling communities described for harbour oreas of the Buenos Aires Province. Associations between fouling samples are based on specific components and enviromental factors related with tidal levels.
- Contribucion a revistaAcceso AbiertoPublicaciones científicas y técnicas realizadas por el CIDEPINT (Período 1993-1998)(1998) Centro de Investigación y Desarrollo en Tecnología de PinturasIncluye listados de: - Publicaciones en revistas internacionales de la especialidad - Publicaciones en proceedings de congresos y reuniones científicas - Publicaciones en revistas nacionales y en CIDEPINT-Anales
- ArtículoAcceso AbiertoHigh performance anticorrosive epoxy paints pigmented with zinc molybdenum phosphate(1998) Romagnoli, Roberto; del Amo, Beatriz; Vetere, Vicente; Véleva, L.Zinc molybdenum phosphate belongs to the so called second generation phosphate pigments and is claimed to have equal or greater anticorrosive properties than chromates and better than zinc phosphate alone. Little Information is available in the literature about its anticorrosive performance. The aim of this research was to stucfy the anticorrosive performance of zinc molybdenum phosphate in solvent borne epoxy paints employing two anticorrosive pigment loadings. The effect of incorporating zinc oxide as complemetary pigment was also studied SAE 1010 Steel ponéis were primed and coated with three different paint systems containing the anticorrosive paint and this paint plus a sealer cmd/or a topcoat. The anticorrosive efftciency of the different paint systems was assessed by accelerated tests (salí spray, humidity and accelerated weathering). Electrochemical measurements were done employing the anticorrosive paints alone. Results showed that the highest anticorrosive effect was obtained employing 30% of zinc molybdenum phosphate. Polarization measurements showed that the anoche film formed on Steel blocked the active sites for oxygen reduction. The incorporation of zinc oxide to pigment formula was detrimental due to its high water absorption and to the fact that it reduced zinc molybdenum phosphate solubility by the common ion effect. Polarization curves of pigments mixtures could be used as a guideline to precüct the anticorrosive coating performance in accelerated and electrochemical tests. However, the final decisión on pigment selection musí be taken on the basis of accelerated triáis.
- ArtículoAcceso AbiertoFactores que afectan la estructura de recubrimientos de cinc obtenidos por inmersión(1998) Seré, Pablo Ricardo; Culcasi, José Daniel; Elsner, Cecilia Inés; Di Sarli, Alejandro RamónCoating solidification during hot-dip galvanizing is very complex due to Al-Fe, Al-Fe- Zn and Fe-Zn intermetallic compounds development. Fe-Zn ones are brittle and detrimental for mechanical properties, while the diffusion towards the surface of a segregated insoluble alloying such as antimonium causes the sheet darkness. Steel sheets of different roughness were hot-dip galvanized under different operation conditions using a laboratory scale simulator. The effect of steel roughness and process parameters upon coating characteristics were analysed Experimental results showed that the steel roughness affects the coating thickness, zinc grain size and texture as well as the out-bursts development, while the process parameters effects the Fe2Al5 morphology and anümonium segregation.
- Publicación periódicaAcceso AbiertoAnales CIDEPINT 1997-98(1998) Centro de Investigación y Desarrollo en Tecnología de Pinturas- The use of polymerisable surfactants in emulsión copolymerization for coatings application; J.L. Amalvy, M.J. Unzué, H.A.S. Schoonbrood, J.M. Asua - The performance of zinc molybdenum phosphate in anticorrosive paints by accelerated and electrochemical tests; B. del Amo, R. Romagnoli, VF. Vetere - Formulation and testing of a water-borne primer containing chestnut tannin; O.R. Pardini, J.L Amalvy, R. Romagnoli, V.F. Vetere - Phosphorus-based intumescent coatings; J.C. Benítez, C.A. Giúdice - Extraction and characterisation of quebracho (Schinopsis sp.) tannins; M.L. Tonello, C.A. Giúdice, J.C. Benítez - Manufacture and testing of water-based tannic pretreatments; C.A. Giúdice, J.C. Benítez, M.L. Tonello - Tin tannates and iron tannates in corrosion-inhibiting coatings; C.A. Giúdice, J.C. Benítez, M.L. Tonello - SEM study of intermetallic phases growth in a hot-dip galvanizing process; P.R. Seré, J.D. Culcasi, C.I. Elsner, A.R. Di Sarli - Influence of differences between sample and mobile phase viscosities on the shape of chromatographic elution profiles; R.C. Castells, C.B. Castells, M.A. Castillo - Concurrent solution and adsorption of hydrocarbons in gas chromatographic columns packed with different loadings of 3- methylsydnone on chromosorb P10; R.C. Castells, L.M. Romero, A.M. Nardillo - Theoretical and practical aspects of flow control in programmed- temperature gas chromatography; F.R. González, A.M. Nardillo - Retention in multistep programmed-temperature gas chromatography and flow control linear head pressure programs; F.R. González, A.M. Nardillo - Integration of the equation of peak motion in programmed-pressure and -temperatura gas chromatography; F.R González, A.M. Nardillo - Comunidades incrustantes de áreas costeras naturales del sur de la Provincia de Buenos Aires (Argentina); R Bastida, J.P. Martin, E. Ieno - Studies on biofouling at Mar del Plata harbor. Monthly settlement of calcareous species along a year; M.C. Pérez, M.T. García, M.E. Stupak - High performance anticorrosive epoxy paints pigmented with zinc molybdenum phosphate; R Romagnoli, B. del Amo, VF. Vetere, L. Véleva - Steel corrosión protection by means of alkyd paints pigmented with calcium acid phosphate; B. del Amo, R Romagnoli, VF. Vetere - Publicaciones científicas y técnicas realizadas por el CEDEPINT (Período 1993-1998)
- ArtículoAcceso AbiertoIntegration of the equation of peak motíon in programmed-pressure and-temperatura gas chromatography(1998) González, F. R.; Nardillo, A. M.Numerical procedures for the estimation of the retention are compared considering the simultaneous programming of temperature and column head pressure , embracing issues from the mathematical basis to the practical aspects in the simulation of the chromatographic process by Computer.