1,720,967 research outputs found
Facile preparation of soluble poly(2-aminothiazole)-based composite coating for enhanced corrosion protection in 3.5% NaCl solution
No full textConducting polymer-based coating is the prospective alternative in consideration of environmentfriendly coatings for corrosion protection of metallic substrate. Minimally-researched poly(2-aminothiazole) (PAT) with well-dispersion and good processability was synthesized successfully via radical polymerization and explored to prepare novel PAT/epoxy composite coatings on Q235 steel. The anticorrosive performance of PAT-based composite coatings was evaluated by electrochemical impedance spectroscopy, potentiodynamic polarization technique and scanning vibrating electrode technique in 3.5 wt % NaCl solution. The corrosion protective mechanism of poly(2-aminothiazole) was proved by the identification of rust layer beneath the composite coating
Surface modification of Mg/Al layered double hydroxide by camphorsulfonic acid doped polyaniline and its applications for anticorrosive coating
No full textAlthough Mg/Al layered double hydroxide has significant anion exchange capability and hydrophobicity, its layer-blocking performance is rarely investigated for anti-corrosive performance. In this work, the camphorsulfonic acid doped polyaniline(CPANI)-modified Mg/Al layered double hydroxide (LDH) composites were successfully prepared through oxidative polymerization with an aim to improve dispersion of hydrotalcite in waterborne epoxy resin. Through a series of basic characterizations, camphorsulfonic acid doped polyaniline was successfully coated on the surface of layered double hydroxide and its dispersibility in water was greatly improved. In addition, the CPANI modified LDH was pigmented into waterborne epoxy resin to form a composite coating, further, potentiodynamic curve and electrochemical impedance spectroscopy were employed to study the corrosion behavior in 3.5 wt% NaCl aqueous solution. Composite coating with CPANI/LDH exhibited excellent anticorrosion performance owing to the barrier and passive effect of LDH and CPANI. The optimized specimen CAPNI/LDH0.5% presents a superior barrier property during 45 d immersion compared with pure epoxy coating
Synergistic Effect of Polypyrrole-Intercalated Graphene for Enhanced Corrosion Protection of Aqueous Coating in 3.5% NaCI Solution
No full textDispersion of graphene in water and its incorporation into waterborne resin have been rarely researched and hardly achieved owing to its hydrophobicity. Furthermore, it has largely been reported that graphene with impermeability contributed to the improved anticorrosion property. Here, we show that highly concentrated graphene aqueous solution up to 5 mg/mL can be obtained by synthesizing hydrophilic polypyrrole (PPy) nanocolloids as inter-calators and ultrasonic vibration. On the basis of pi-pi interaction between PPy and graphene, stacked graphene sheets are exfoliated to the thickness of three to five layers without increasing defects. The corrosion performance of coatings without and with PPy and graphene is obtained by potential and impedance measurements, Tafel curves, and fitted pore resistance by immersing in a 3.5 wt % NaCl solution. It turns out that composite coating with 0.5 wt % graphene additive exhibits superior anticorrosive ability. The mechanism of intercalated graphene-based coating is interpreted as the synergistic protection of impermeable graphene sheets and self-healing PPy and proved by the identification of corrosion products and the scanning vibrating electrode technique
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Water Soluble Trianiline Containing Polyurethane (TAPU) as an Efficient Corrosion Inhibitor for Mild Steel
No full textNovel trianiline containing water soluble polyurethane (TAPU) was synthesized by polymerization of polyethylene glycol, toluene diisocyanate and amine-capped aniline trimer. The influence of TAPU on the corrosion inhibition of mild steel in 1 M HCl was investigated using weight loss measurements, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS). The performance of TAPU on the corrosion inhibition of mild steel was also evidenced by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and atomic force microscope (AFM). Results confirmed that the adsorption of TAPU on the mild steel surface and consequent inhibition of the corrosion process. The inhibition efficiency (IE%) increased with a rise in TAPU concentration, reaching a value up to 97% at a concentration of 200 mg/l. Potentiodynamic polarization curves showed that the TAPU affected both cathodic and anodic protection and was a mixed type inhibitor in HCl corrosive medium. Adsorption isotherm studies confirmed that the adsorption of TAPU on the mild steel surface in 1 M HCl solution obeyed Langmuir adsorption isotherm. EDS analysis determined the adsorption of TAPU molecules on the steel surface, and the absorbed TAPU provided an effective corrosion inhibition in 1 M HCl solution from observation of surface morphology by SEM and AFM
In situ polymerization of sulfonated polyaniline in layered double hydroxide host matrix for corrosion protection
No full textThe hybrid material of sulfonated polyaniline/Mg Al layered double hydroxides (SPANi/LDHs) was obtained through polymerization of o-aminobenzenesulfonic acid and aniline in the galleries of LDHs. The structure of SPANi/LDH was characterized by field-emission scanning electron microscopy, X-ray diffraction, Fourier transformed infrared and Raman spectroscopy. The as-prepared SPANi/LDH showed an irregular lamellar shape with an average diameter of 4-6 m and offset of XRD reflections, which revealed that SPANi successfully grew between the LDH interlayers and expanded the interlayered structure slightly. Besides, the monolayer thickness of the SPANi/LDH was about 2.67 nm, which exhibited a significant structure of a nanosheet. The as-prepared SPANi/LDHs hybrids were applied to waterborne epoxy coatings for steel substrates and exhibited significant corrosion protection capacities compared with those of neat epoxy and pure SPANi blended epoxy composites. The electrochemical impedance spectroscopy (EIS) technique was used to describe the electrochemistry dynamics and remarkable corrosion protection performance. Furthermore, corrosion products beneath the epoxy coatings immersed in a 3.5 wt% NaCl aqueous solution were also investigated, which indicated the barrier property and passivation effect of SPANi/LDH. In addition, the mechanism of corrosion inhibition was explored via the analysis of rust layers, and the barrier effect and passivation effect of the composite materials was also demonstrated
Noncovalent Functionalized Graphene-Filled Polyimides with Improved Thermal, Mechanical, and Wear Resistance Properties
No full textA facile method is proposed to prepare poly-o-phenylenediamine (PoPD) noncovalent functionalized graphene (G)-reinforced polyimide (PI) nanocomposites. PoPD-G exhibited excellent dispersibility in various organic solvents. The structures of PoPD-G were characterized by Raman and UV spectrum, which verified the pi-pi interactions between PoPD and G. The effective exfoliation of graphene nanosheets was investigated by observation of the morphology of PoPD-G with SEM, SPM, and TEM. Compared to PI/G composites, the interfacial adhesion between graphene nanosheets and PI matrices promoted efficient stress transfer from PI chains to PoPD-G nanofillers. Polyimide nanocomposites with different incorporations of PoPD-G exhibited outstanding thermal properties. It is interesting to note that only 0.5 wt% PoPD-G-reinforced PI composites increased by 20.8% in hardness, enhanced by 84.0% in storage modulus, and reduced by 72.8% in wear rate compared with neat PI. The eminent enhancement was attributed to the facile dispersion of graphene nanosheets and strong interface adhesion between PI and PoPD-G
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