1,721,051 research outputs found
Zinc-rich paint coatings containing either ionic surfactant-modified or functionalized multi-walled carbon nanotube-supported polypyrrole utilized to protect cold-rolled steel against corrosion
No full textThe intense anodic action of sacrificial zinc pigments ensured viable galvanic function of the highly porous liquid zinc-rich paints (ZRPs) result in deteriorated long-term corrosion resistance often accompanied by cathodic delamination phenomena. In our approach, such a efficacy problem related to the corrosion preventive function of ZRPs is addressed by the application of intimately structured anodic inhibitor particles composed of nano-size alumina and either polyelectrolyte-modified or chemically functionalized multi-walled carbon nanotubes (MWCNT) supported polypyrrole (PPy) in one specific zinc-rich hybrid paint formulation providing balanced active–passive protective functionality.
High dispersity of the nanotube-free PPy-deposited inhibitor particles (PDIPs) with uneven polymer distribution on the alumina carrier was confirmed by transmission electron microscopy (TEM) observations. Furthermore, the MWCNT-embedded PDIPs indicated almost complete surface coverage of the alumina-nanotube carriers by PPy with decreased microstructure dispersity which is attributed to the effect of double-flocculants type co-deposition of the oppositely charged polymers causing coalescence of the modified particles. Depending on the amount of the nanotubes and their proportion to the quantities of the deposited PPy and polyelectrolyte as well as the concentration of the surfactant, varied micron-scale association of the PDIPs in the suspensions of dissolved alkyd matrix was disclosed by rheology characterization carried out at particular solid contents similar to hybrid paint formulation. The evenly distributed but less densely packed nano-structure of PPy was evidenced on the polyelectrolyte-modified nanotubes by Fourier-transform infrared (FTIR) spectroscopy whereas more compact polymer film formation was confirmed on the surface of functionalized nanotubes. According to the greater electrical conductivity, enhanced electroactivity and reversibility of the nanotube-embedded PDIPs were indicated over the nanotube-free particles by cyclic voltammetry, depending on the type and the amount of the nanotubes and their modification.
Protection function of the hybrid paint coatings (formulated with spherical zinc pigment at 70 wt.%) was investigated by immersion and salt-spray chamber tests over 254 and 142 day periods, respectively. Firm barrier nature of the nanotube-embedded PDIP contained hybrids was proved by electrochemical impedance spectroscopy (EIS) and radio-frequency glow-discharge optical-emission-spectroscopy (RF-GD-OES). Furthermore, due to the increased conductivity of the nanotube-embedded PDIPs cemented in epoxy primers optimally at 0.4 and 0.6 wt.%, altered corrosion preventive behaviour of the hybrid coatings was indicated by the positively polarized open-circuit potentials (OCPs) and the X-ray photoelectron spectroscopy (XPS) detected lower relative quantities of the interfacially accumulated zinc corrosion products, moderate oxidative degradation of the epoxy vehicle. Decreasing oxidative conversion of iron at the surface was indicated by XPS found to correlate with the increasing intensity of zinc corrosion and decreasing oxidative degradation of the epoxy binder, according to the higher nanotube contents of hybrid coatings. In addition, inhibited zinc corrosion caused low rate of oxidative degradation of epoxy, allowing increased durability of coating adhesion and cohesion thereby ensuring reliable protection by zinc-rich compositions.
As a conclusion, modified or functionalized MWCNTs acting as unexchangeable doping agents promote enhanced reversibility and increased conductivity of PPy, forming nano-size inhibitor particles with advanced features. Thus, such inhibitor nano-particles in zinc-rich hybrid compositions afford improved barrier and high efficiency galvanic–cathodic corrosion preventive function, exceeding long-term protection capability of the conventional ZRPs
Carbon Nanotubes as Material Support for Pt-Based Catalysts and their Use in Direct Methanol Fuel Cells
No full textIn the last decade carbon nanotubes have turned out to be an important industrial material, being produced hundreds of tons each year. The unique structure of carbon nanotubes makes them an alternative material for catalyst support in fuel cells devices due to their unique one-dimensional nanostructure, high surface area, excellent electronic conductivity, and high chemical and mechanical stability. However, raw nanotubes do not have sufficient binding sites for anchoring metals nanoparticles, which frequently lead to poor dispersion and agglomeration of the nanoparticles. Hence, functionalization of carbon nanotubes is generally an essential issue to further applications. The presence of these surface functional groups modifies the chemical and physical properties of the carbon, improving wettability, adsorption, and cation exchange capacity. Furthermore, these groups act as nucleation centers or anchoring sites, limiting the particle growth and improving the dispersion of metallic crystallites and the stability of the supported catalysts. This chapter is devoted to review the available scientific literature, motivated by the enormous world-wide demand of increasing the production of energy from green renewable technologies. In the need of developing new, better-performing catalysts for direct methanol fuel cells applications, the present survey is focused on synthesis of catalytically active metal nanoparticles, such as Pt, and Pt-Me (Me: Ru, Sn, Mo, Os, etc.) decorating the external walls or the interior of the carbon nanotubes and carbon nanotubes/polymer composites.Fil: Sieben, Juan Manuel. Universidad Nacional del Sur. Departamento de Ingeniería Química. Instituto de Ingeniería Electroquímica y Corrosión; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; ArgentinaFil: Duarte, Marta María Elena. Universidad Nacional del Sur. Departamento de Ingeniería Química. Instituto de Ingeniería Electroquímica y Corrosión; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentin
Bone tissue restoration by nanoscale features of biomaterials
No full textFrom a biomechanical point of view, bone tissue itself can be described as a nanocomposite of organic (mainly collagen) and inorganic (mainly calcium phosphates) components hierarchically organized from the nano- to the macroscale. Nanostructured biomaterials mimicking the native bone architecture are a new tendency in orthopedic technology since they play a cardinal role in bone regeneration: their chemical and structural similarity to the natural tissue and their comparable size to biomolecules and bio-microstructures provide with enormous possibilities to induce desirable biological responses. Along this chapter, an overview of the current knowledge of bone tissue regeneration is discussed focusing on the importance of nanometer-sized entities, their structure and chemical aspects that might enhance bone healing. Consequently, high emphasis is concentrated on the existing state of the art in nanotechnology in order to be able to narrow the gap between current design strategies and submicron tissue elements to obtain new biomaterials with improved properties.Fil: Gravina, Noel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: D'elía, Noelia Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Sartuqui, Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Messina, Paula Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentin
Polymer nanocomposites and related legal issues: an overview.
Get PDFManipulation of engineered nanomaterials (ENMs) to develop different consumer and industrial products are the preferred choice in modern day industrial production due to their unprecedented, but diversified promises and prospects. The researchers claimed in 2006 that the NMs were in a stage where plastic was in the 1960s. This analogy was made to indicate the potential wide use of the NMs in consumer and industrial products. Burgeoning research has been carried out in almost every corner of the world to explore and exploit the prospects of ENMs. Application of nanoparticles (NPs) into polymer matrix materials have also been tested, and dramatic changes in the mechanical, thermal, electrical, and diffusion properties to the properties of the host polymers were observed. The polymer nanocomposites (PNCs) are undoubtedly very prospective and it can be anticipated that PNCs will widely be used in the automotive industry to replace the metal accessories and to reduce CO2 emissions. However, in order to do so, it is crucial that the manufacturers handle different socio-legal and regulatory issues around the ENMs and PNCs carefully. This record only contains an introduction to the chapter, the full chapter is available from: https://doi.org/10.1016/B978-0-12-811033-1.00026-
Capture of water contaminants by a new generation of sorbents based on graphene and related materials
No full textGrowing concern about water contamination along with the necessity of ensuring water quality and sustainable management of limited water resources have led to the search of more efficient and selective materials for use in sorption-based technologies. They are widely applied for the capture of a variety of different pollutant species in wastewater treatment, due to robustness, easy operation, and relatively low cost. Inspired by the unique nanostructure of graphene and its exceptional properties, efforts have been directed toward the development of a new generation of sorbents based on this latest carbon allotrope, related nanostructures, and/or derived nanostructured composites for the removal of water contaminants. Main advances attained in this field in the last few years are reviewed in the present chapter. The first part is devoted to recent efforts targeted at the development of highly efficient graphene-based nanosorbents for the capture of polluting inorganic and water-soluble organic species, mainly including heavy metals, nonmetal anions, dyes, and pharmaceuticals, whereas the second one provides latest progresses toward using graphene and related materials as advanced sorbents for cleanup of oil spills and removal of some other water-insoluble organic contaminants.Fil: Cukierman, Ana Lea. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria; Argentina. Universidad de Buenos Aires; ArgentinaFil: Bonelli, Pablo Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias; Argentin
Recent developments in waterborne polyurethanes for coating applications
Get PDFIn recent years, the need to use more environmentally friendly polymers has emphasized research for the development of polymers in dispersions in water. In an effort to meet this goal, water-based polyurethanes (WBPUs) were developed, which release almost benign water vapour to the atmosphere during use as supported or self-standing films for different applications instead of huge amounts of volatile organic compounds (VOCs), as is the case with most traditional solvent-based polymers. One of the most studied applications for this type of materials are water-based paints for coatings applications. In this chapter, we will analyse the latest advances regarding the development of WBPU from multiple hydroxyl group (OH) sources, as well as the different types of chain extenders and emulsifiers used in their preparation. On the other hand, to improve performance according to the aimed (required) or final application, mechanical properties (tensile strength, elasticitry, hardness), water resistance, thermostability, adhesion or anti-adhesion on substrate, antibacterial adhesion (antifouling) and hydrophobic property, composite formulations are tailored through the addition of organic or inorganic particles/nanoparticles. In this chapter we will briefly review neat and composite WBPUs that have been developed as specific coatings for different substrates.Fil: Mucci, Veronica Lujan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Aranguren, Mirta Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Amalvy, Javier. Universidad Tecnológica Nacional. Facultad Regional La Plata. Centro de Investigación y Desarrollo en Ciencia y Tecnología de Materiales; ArgentinaFil: Hormaiztegui, Maria Eugenia Victoria. Universidad Tecnológica Nacional. Facultad Regional La Plata. Centro de Investigación y Desarrollo en Ciencia y Tecnología de Materiales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
Bacterial Cellulose Nanofibers for Efficient Removal of Hg<sup>2+</sup> from Aqueous Solutions
No full textThe removal of mercury from wastewater is gaining much attention because of being one of the common heavy metal pollutants found in water source affecting human health and environment. Dye affinity chromatography is a general method for heavy metal removal having high reactivity, stability, easiness, and cost effectiveness. In this study, modified bacterial cellulose nanofibers (BC) were prepared using a dye namely Cibacron Blue F3GA (CB). The covalently attached Cibacron Blue F3GA (17.8 × 104 nmol/g) to the bacterial cellulose nanofibers was successfully applied to remove Hg2+ from aqueous solutions. Cibacron Blue F3GA attachment onto the bacterial cellulose nanofibers significantly increased the Hg2+ adsorption (928.0 mg/g), while the adsorption of Hg2+ onto the unmodified bacterial cellulose nanofibers was obtained very low (0.62 mg/g polymer). The competitive adsorption of heavy metals on BC-CB nanofibers was performed to examine the efficiency of BC-CB nanofibers for Hg2+ in comparison with other divalent metal ions. The adsorption capacities were observed as 322.4 mg/g for Hg2+; 48.5 mg/g for Cd2+; and 41.9 mg/g for Pb2+ indicating higher specificity for Hg2+ adsorption onto BC-CB nanofibers for the mercury ions comparing to other ions. The successive adsorption experiments and elution process demonstrated the efficient repeated workability of modified BC nanofibers. The results show that the preparation of cheap, effective, and eco-friendly nanofibers for mercury removal was performed successfully indicating the potential of BC-CB nanofibers for metal ion removal applications. © 2018 Scrivener Publishing LLC. All rights reserved
Biofunctional Textiles: Functional polymer-carriers with antiviral, antibacterial, antifungal, and repellent activity
No full textThe aim of this review is to describe biofunctional systems reported, formed by vehicles of natural origin that transport active compounds (natural substances) to inhibit microorganisms. In particular, essential oils, which have antibacterial, anti-fungal and antiviral activities in order to use them as micro and nano-finishes in woven and non-woven textiles oriented to the field of bios health are described here.Fil: Martínez, María Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Gende, Liesel Brenda. Universidad Nacional de Mar del Plata. Instituto de Investigaciones en Producción, Sanidad y Ambiente. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Producción, Sanidad y Ambiente; ArgentinaFil: Alvarez, Vera Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Gonzalez, Jimena Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin
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