Anales CIDEPINT 1996
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Acceso Abierto Revisión sobre los aspectos biológicos del "fouling"(1996) Pérez, M. C.; Stupak, M. E.The development of fouling communities is object of world-wide research since the last half of the century. Biological fouling of vessels has been known since the beginning of man ’s maritime activities. Biological corrosión became a problem of concern when steel replaced wood as the primary ship construction material. The purpose of the present paper is to present a guide about biological aspects of fouling for the non-specialist (the non-biologist). The scope ofthis guide is to give some historical references, development sequences of the fouling community, abiotic factors influence, fouling problems, study methodology and enough elements to recognize the most important taxa with some pictures. Also, in relation to freshwater fouling, a basic approach and comments about exotic species introduction by ships are presented. A glossary and a broad bibliography on this subject are ineluded. - Artículo
Acceso Abierto Thermodynamics of solutions of hydrocarbons in low molecular weight poly(isobutylene): a gas chromatographic study(1996) Castells, R.C.; Romero, L. M.; Nardillo, A. M.The reduced chemical potentials (x*) of twenty normal and branched alkanes, cyclohexane and three aromatic hydrocarbons at infinite dilution in polyisobutylene (PIB) were measured by gas-liquid chromatography at five temperatures between 35 and 65°C. Reduced partial molar residual enthalpies (k*) were calculated from the temperature dependence of x*; they are positive for PIB+alkane systems, but smaller than those obtained in former chromatographic studies. Although uncertainties on k* are at least one order of magnitude larger than those on x*, binary X12 Flory parameters obtained from k* display a good correlation with the structural parameter 0ɵv defined as the ratio of the number of hydrogen atoms on methyl groups to the total number of hydrogen atoms in the alkane molecule. Very poor or nil correlation exists between X12 values obtained from x* and 0ɵ1. The evidence is by no means conclusive, but in principie the x* results obtained for PIB + alkane systems could be explained in terms offree volume contributions and of the antipathy between methyl groups on the alkanes molecules and the polymer side groups. Positive partial molar residual entropies were detected for the three aromatic hydrocarbons; their partial molar residual enthalpies are however highly positive, resulting in their poor solvent properties towards PIB. - Artículo
Acceso Abierto Activity coefficients of hydrocarbons at infinite dilution in di-n-octyltin dichloride: comparison with results obtained in other alkyltin solvents(1996) Nardillo, A. M.; Soria, Delia Beatriz; Castells, C. B. M.; Castells, R.C.The gas chromatographic method was employed to measure the infinite dilution activity coefficients of twenty-eight hydrocarbons of different types in di-n-octyltin dichloride between 323.15 and 353.15 K, and ofseven branched alkanes in tri-n-octyltin chloride between 313.15 and 333.15 K. A comparison is made between the results obtained for all the solutes in both solvents and in tetra-n-octyltin. - Artículo
Acceso Abierto Thermodynamic consideration of the retention mechanism in a poly(perfluoroalkyl ether) gas chromatographic stationary phase used in packed columns(1996) Castells, R. C.; Romero, L. M.; Nardillo, A. M.Retention voluntes of fifteen hydrocarbons were measured in columns containing several concentrations of a commercial poly(perfluoroalkyl ether), Fomblin Y HVAC 140/13, as the stationary phase. Two different type ofpacking were studied: one ofthem employed pre-silylated Chromosorb P AW DMCS as the solid support, and the other type wasprepared by coating the stationary phase on Chromosorb P AW and silylating on-column. On-column silylated columns showed unequivocal symptoms of partial deactivation; retention volumes changed regularly with the contení of stationary phase in pre-silylated columns. Analysis of retention in pre-silylated columns indicates that a mixed mechanism (partition and adsorption on the gas-liquid interface) is operative. Systems hydrocarbon + perfluorocompound show pronounced positive deviations from the ideal behaviour that can be attributed to repulsión between the hydrocarbon and the perfluorocompund segments. - Artículo
Acceso Abierto Recent developments in miniemulsion polymerization(1996) Aizpurua, I.; Amalvy, Javier Ignacio; Baralidiaran, M. J.; de la Cal, J. C.; Asua, J. M.Some developments in miniemulsion polymerization aiming at taking advantage of its unique mechanisms minimizing the drawbacks of this technique are discussed. The discussion ineludes preparation of highly concentrated latexes, miniemulsion polymerization in continuous stirred tank reactors (CSTRs), and elimination of the low molecular weight hydrophobe. - Artículo
Acceso Abierto Dilute-solution viscosimetry and solution properties of colloidal polymers(1996) Amalvy, Javier IgnacioThe intrinsic viscosities of a terpolymer of methyl methacrylate, ethyl acrylate and methacrylic acid, prepared by semicontinuous emulsión polymerization (látex) were measured in acetone and THF at different temperatures. Data were analyzed with the aid of the equations of Huggins, Kraemer, Martín, Schulz-Blaschke and an equation recently suggested by Rao. Relationships between different parameters were also considered The effects of low-molecular weight and water-soluble compounds on the intrinsic viscosities were observed for uncleaned samples of látex as compared to samples purified, by single precipitation or by dissolution and precipitation from THF. Solvent powers and effects of degree of purification and temperature on viscosity are discussed. Polymer-solvents interactions are discussed in terms of the acceptor / donor properties of the solvents. - Artículo
Acceso Abierto Chemical and electrochemical assessment of tannins and aqueous primers containing tannins(1996) Vetere, Vicente; Romagnoli, RobertoWhen the mechanical cleaning of metallic surfaces is not possible, some chemical treatments are an important possibility. The benefit of using acidified aqueous suspensions of tannins in this field has been recognized for more than thirty years. However, little is known about the action of these substances on rusted surfaces. Thus, the chemical reaction of tannins with soluble and precipitated ferric species was studied. The influence of the phosphate anion was also considered. At the same time, cleaned and oxidized steel surfaces, treated with tannin suspensions were analyzed by microscopy and scanning electrón microscopy (SEM) to observe the surface film morphology. Four tannins were selected to carry out this investigation: quebracho, sulphitated quebracho, mimosa and chestnut. The experimental results show that each tannin reacts with soluble and precipitated ferric species in a different way. This reaction depends on the pH of the solution. The tannate film formed on the steel surfaces had a píate morphology which also depended on the tannin. The presence of phosphoric acid contributed to the tannate film building. - Artículo
Acceso Abierto Study of formulation variables of thermoplastic reflecting materials for traffic marking(1996) Aznar, Alberto C.; Caprari, Juan J.; Meda, Jorge F.; Slutzky, O.Nine formulations of thermoplastic materials for traffic marking were prepared using a resin based on maleic anhydride modified with rosin in different proportions (18, 22 and 26%). As plasticizer a liquid coconut long oil alkyd resin (100% solids) was employed Hiding pigment was titanium dioxide; calcium carbonate and micronized tale were used as extenders. Coarse marble powder is used to facilítate the incorporation of glass beads. The operation was made employing a double Z mixer oil heated to obtain a mass temperature of 180-190 QC. The mixer was provided with two asynchronous arms rotating at 46 rpm. Dry and wet abrasión tests were carried out and the obtained results indicated that wearing valúes are three times greater in the case of the wet test. It is demonstrated that plasticization degree controls hardness variation as a function of temperature, determining a critical point which is the beginning of an abrupt reduction of hardness. Water absoption increases when plasticizer content increases. Matrix correlation of tests results was used to analize the obtained numeric valúes. - Artículo
Acceso Abierto Effect of the paint application method on adhesion and corrosion resistance of an alkyd coated steel(1996) Seré, Pablo Ricardo; Santágata, D. M.; Elsner, Cecilia Inés; Di Sarli, Alejandro RamónThe influence of the paint application method (spinning (Sn), rollering (R), brushing (B) and spraying (Sy)) on the behaviour of steel/alkyd coating/aqueous aggressive médium systems was analized. Experimental results obtained from electrochemical and standardized tests allowed to conclude that: a) all intact coated samples showed a high resistance to the strong aggressive médium of the salt spray cabinet; b) cross scribed ones only show corrosión at and cióse to the cross; c) from the electrochemicalpoint of view, the corrosión potential, ionic and charge transfer resistance evolution on immersion time suggests that the alkydpaint applied by the four different methods used have relatively goodprotective properties, in the order Sy > R s Sn > B, at the present environmental conditions. - Publicación periódica
Acceso Abierto Anales CIDEPINT 1996(1996) Centro de Investigación y Desarrollo en Tecnología de Pinturas- Effect of the paint application method on adhesión and corrosion resistance of an alkyd coated steel; P.R. Seré, DM. Santágata, CI. Elsner, AR. Di Sarli - Study of formulation variables of thermoplastic reflecting materials for traffic marking; AC. Aznar, JJ. Caprari, J.F. Meda, O. Slutzky - Chemical and electrochemical assessment of tannins and aqueous primers containing tannins; V.F. Vetere, R. Romagnoli - Dilute-solution viscosimetry and solution properties of colloidal polymers; J.I. Amalvy - Recent developments in miniemulsion polymerization; I. Aispurua, J. I. Amalvy, MJ. Barandiaran, J.C. de la Cal, J.M. Asua - Thermodynamic consideration of the retention mechanism in a poly(perfluoroalkyl ether) gas chromatographic stationary phase used in packed columns; R.C. Castells, L.M. Romero, AM. Nardillo - Activity coefficients of hydrocarbons at infinite dilution in di-n-octyltin dichloride. Comparison with results obtained in other alkyltin solvents; A.M. Nardillo, D.B. Soria, C.B.M. Castells, R.C. Castells - Thermodynamics of solutions of hydrocarbons in low molecular weight poly(isobutylene). A gas chromatographic study, R.C. Castells, L.M. Romero, A.M. Nardillo - Revisión sobre los aspectos biológicos del “fouling”; M.C. Pérez, M.E. Stupak - New trends in industrial painting; V.J.D. Rascio - Comparative corrosión behaviour of 55aluminiun-zinc alloy and zinc hot-dip coatings deposited on low carbón steel substrates; P.R. Seré, M. Zapponi, C.I. Elsner, A.R. Di Sarli - Reactive surfactants in heterophase polymerization of high performance polymers. VIH. Emulsión polymerization of alkyl sulfopropyl maléate polymerizable surfactants (surfmers) with styrene; H.A.S. Schoonbrood, MJ. Unzué, J.I. Amalvy, J.M. Asua - Gas chromatography of aliphatic amines on diatomaceous solid supports modified by adsorption and crosslinking of polyethyleneimines; A.M. Nardillo, R.C. Castells - Excess enthalpies of nitrous oxide + pentane at 308.15 and 313.15 K from 7.64 to 12.27 MPa; J.A.R. Renuncio, C. Pando, C. Menduiña, R.C. Castells - Separation of low-boiling pyridine bases by gas chromatography; M.C. Titon, A.M. Nardillo - Evaluation of the surface treatment effect on the corrosión performance of paint coated carbón steel; D.M. Santágata, P.R. Seré C.I. Elsner, A.R. Di Sarli