Investigation of the Structural Change of Doped Polyaniline during Heat Treatment

2009 ◽  
Vol 87-88 ◽  
pp. 311-316 ◽  
Author(s):  
Hui Huang ◽  
Zhong Cheng Guo
Keyword(s):  
Crystal Structure ◽  
Heat Treatment ◽  
Acidic Medium ◽  
Structural Changes ◽  
Oxidative Polymerization ◽  
Chemical Oxidative Polymerization ◽  
Ammonium Peroxydisulfate ◽  
Heat Treated ◽  
Doped Polyaniline ◽  
Aqueous Acidic Medium

Doped polyaniline (PANI) was synthesized by chemical oxidative polymerization of aniline in aqueous acidic medium with mixed sulfuric acid and 5-sulfosalcyclic acid as complex dopant , and ammonium peroxydisulfate as an oxidant, and heat treated at 150°C, 200°C, 250°Cand 300°C for 2 hours in vacuum. Different intrinsic and extrinsic structural changes due to heat treatment were determined from FTIR and XRD measurements. When PANI is subjected to heat treatment, different changes are taking place in the system like doping, dedoping (extrinsic), oxidation and changes in crystal structure (intrinsic). Mechanisms for doping, dedoping and oxidation, are proposed.

Heat Treatment Influence on the Corrosion Resistance of a Cu-Al-Fe-Mn Bronze

2018 ◽  
Vol 69 (5) ◽  
pp. 1055-1059 ◽  
Author(s):  
Mariana Ciurdas ◽  
Ioana Arina Gherghescu ◽  
Sorin Ciuca ◽  
Alina Daniela Necsulescu ◽  
Cosmin Cotrut ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Structural Changes ◽  
Heating Temperature ◽  
Galvanic Corrosion ◽  
Cooling Water ◽  
Open Circuit ◽  
Water Quenching ◽  
Heat Treated ◽  
Different Temperatures

Aluminium bronzes are exhibiting good corrosion resistance in saline environments combined with high mechanical properties. Their corrosion resistance is obviously confered by the alloy chemical composition, but it can also be improved by heat treatment structural changes. In the present paper, five Cu-Al-Fe-Mn bronze samples were subjected to annealing heat treatments with furnace cooling, water quenching and water quenching followed by tempering at three different temperatures: 200, 400 and 550�C. The heating temperature on annealing and quenching was 900�C. The structure of the heat treated samples was studied by optical and scanning electron microscopy. Subsequently, the five samples were submitted to corrosion tests. The best resistance to galvanic corrosion was showed by the quenched sample, but it can be said that all samples are characterized by close values of open-circuit potentials and corrosion potentials. Concerning the susceptibility to other types of corrosion (selective leaching, pitting, crevice corrosion), the best corrosion resistant structure consists of a solid solution, g2 and k compounds, corresponding to the quenched and 550�C tempered sample.

Electrochemical Studies on Corrosion Resistance of Coatings Based on Polyaniline and Silica Gel

2021 ◽  
Vol 1167 ◽  
pp. 13-22
Author(s):  
C.C. Soumya ◽  
K.E. George ◽  
Sunil K. Narayanankutty
Keyword(s):  
Silica Gel ◽  
Electrochemical Impedance ◽  
Oxidative Polymerization ◽  
Corrosion Current ◽  
Nacl Solution ◽  
Chemical Oxidative Polymerization ◽  
Ammonium Persulphate ◽  
Protection Efficiency ◽  
Corrosion Studies ◽  
Doped Polyaniline

Organic acid doped polyaniline (PANI), hybrid with silica gel (SiG) and composites with metal primer have been prepared by chemical oxidative polymerization of double-distilled aniline in an acidic medium at 0-5 °C in an ice bath using ammonium persulphate as oxidant and p-toluene sulphonic acid (p-TSA) as the dopant. The anticorrosive property of PANI coatings containing alkyd primer, zinc chromate and silica gel was investigated. The coatings were characterized by FTIR spectroscopy, scanning electron microscopy and electrochemical impedance spectroscopy. The corrosion studies were carried out in a 3.5 wt% NaCl solution. On introduction of SiG, PANI, and PANI-SiG hybrid, the corrosion current decreased from 0.03626 μA to 0.007856 μA, 0.02042 μA, and 0.011 μA, respectively. The penetration rates calculated in mm/yr. for the composites: SiG/Primer, PANI/Primer and PANI-SiG/Primer were 0.430× 10-4, 1.110× 10-4, and 0.599 × 10-4, respectively and that of neat primer was 1.977 × 10-4. The corrosion protection efficiency of the primer was improved up to 7% on introduction of the PANI-based fillers. The 5 wt% of 1:1 PANI-SiG/primer composite, which contains 2.5wt% of PANI, showed better results than that of 5wt% PANI in Primer and these results are very close to that of 5wt% SiG/Primer composites.

scholarly journals Effects of aluminum sulfate soaking pretreatment on dimensional stability and thermostability of heat-treated wood

2020 ◽  
Author(s):  
Lijie Qu ◽  
Zhenyu Wang ◽  
Jing Qian ◽  
Zhengbin He ◽  
Songlin Yi
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Thermal Degradation ◽  
Structural Changes ◽  
Aluminum Sulfate ◽  
Treated Wood ◽  
Treatment Temperature ◽  
Chinese Fir ◽  
Heat Treated ◽  
Thermal Stability Of

Abstract Acidic aluminum sulfate hydrolysis solutions can be used to catalyze the thermal degradation of wood in a mild temperature environment, and thus reduce the temperature required for heat treatment process. To improve the dimensional and thermal stability of Chinese fir during heat treatment at 120 °C, 140 °C and 160 °C, this study investigated the effects of soaking pretreatment with 5%, 10% and 15% aluminum sulfate on the chemical and structural changes of the heat-treated Chinese fir. The results indicated that the samples treated at 15% aluminum sulfate concentration and 160 °C heat treatment achieved the best dimensional and thermal stability. Chemical analyses by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) indicated that the catalysis of aluminum sulfate resulted in degradation of hemicelluloses during the heat treatment, and an increase in the soaking concentration and heat treatment temperature also affected the thermal degradation of celluloses. The scanning electron microscope (SEM) and mass changes test results proved that the hydrolyzed aluminum flocs mainly adhered to the inner wall of the wood tracheid as spherical precipitates, and when the soaking concentration reached 10% and 15%, a uniform soaking effect could be achieved. The thermogravimetric (TG) analysis revealed the soaking pretreatment effectively improved the thermal stability of the heat-treated wood by physically wrapping and promoting the formation of a carbon layer on the wood surface during heat treatment. Thus, aluminum sulfate soaking pretreatment exerted a great effect on the dimensional and thermal stability of wood, allowing heat treatment to be performed at a lower temperature.

Structural Characterization of Poly(o-Tolidine)

2005 ◽  
Vol 494 ◽  
pp. 357-362 ◽  
Author(s):  
G. Ćirić-Marjanović ◽  
B. Marjanović ◽  
M. Trchová ◽  
P. Holler
Keyword(s):  
Spectroscopic Analysis ◽  
Platinum Electrode ◽  
Electrochemical Polymerization ◽  
Oxidative Polymerization ◽  
Gel Permeation Chromatography ◽  
Chemical Oxidative Polymerization ◽  
Ammonium Peroxydisulfate ◽  
Gel Permeation ◽  
Ir Spectroscopic

A new polymer of o-tolidine was synthesized by chemical and electrochemical methods from its aqueous solutions in 1M HCl. Chemical oxidative polymerization was performed using ammonium peroxydisulfate as an oxidant. Electrochemical polymerization was carried out using two steps which were successively repeated in a continual process: first, holding the working platinum electrode under a constant anodic potential of +1.6 V, and second, the voltammetric cycle between +0.3 and +1.6 V. During this procedure a polymeric film was formed on the working electrode. Polymerization of o-tolidine was exactly proved by gel permeation chromatography evidencing the chains of molar masses in the range of 1000 – 12600 g mol─1. The structure of poly(o-tolidines) obtained by both chemical and electrochemical procedures was studied by IR spectroscopy. Coupling pathway N–C during polymerization, existence of quinonoid rings and hydrogen bonding involving NH group in polymeric products are revealed by IR spectroscopic analysis. The mechanism of o-tolidine oxidative polymerization is proposed.

Synthesis and Properties of Conducting Polyaniline by Co-Doping with Sulfosalicylic Acid and Sulfate Acid

2010 ◽  
Vol 663-665 ◽  
pp. 481-485 ◽  
Author(s):  
Hui Huang ◽  
Zhong Cheng Guo ◽  
Ju Kang Li
Keyword(s):  
Fourier Transform ◽  
Oxidative Polymerization ◽  
X Ray Diffraction ◽  
Chemical Oxidative Polymerization ◽  
Sulfosalicylic Acid ◽  
X Ray ◽  
Co Doping ◽  
Doped Polyaniline ◽  
Fourier Transform Raman ◽  
Ft Raman

A chemical oxidative polymerization of aniline sulfosalicylic acid (ANISSA) and aniline sulfate acid (ANIH2SO4) was performed in an aqueous solution. A co-doped polyaniline (PANI) was thus obtained, a higher conductivity than the insoluble H2SO4-doped PANI compressed pellet, and much higher conductivity than that prepared from pure ANISSA. The PANI doped with SSA and H2SO4 was characterized using Fourier-transform infrared spectra (FTIR), Fourier-transform Raman spectra (FT-Raman), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The investigation reveals that SSA and H2SO4 as dopant not only enhances crystallinity of polyaniline but also stability of polyaniline.

scholarly journals Synthesis of H3PW12O40•xH2O-doped polyaniline by chemical oxidative polymerization

2012 ◽  
Vol 27 ◽  
pp. 1448-1453
Author(s):  
Dawei Gu ◽  
Gang Liu ◽  
Jiansheng Wu ◽  
Linjiang Shen
Keyword(s):  
Oxidative Polymerization ◽  
Chemical Oxidative Polymerization ◽  
Doped Polyaniline

scholarly journals D.C electrical conductivity of prepared pure and doped polyaniline salt

2019 ◽  
Vol 15 (33) ◽  
pp. 1-10
Author(s):  
Salma M. Hassan
Keyword(s):  
Aqueous Solution ◽  
Electrical Conductivity ◽  
Applied Voltage ◽  
Oxidative Polymerization ◽  
Dc Conductivity ◽  
Rate Process ◽  
Chemical Oxidative Polymerization ◽  
Pure Sample ◽  
Ft Ir ◽  
Doped Polyaniline

Pure Polyaniline salt, and protonation PANI by H2SO4 were synthesized by electro-chemical oxidative polymerization of aniline with acidity of H2SO4. The solution was prepared in reaction temperature equal 291 K and the acidity of aqueous solution was 1 molarities. The prepared polyaniline was characterized by FT-IR, the result indicate that the intensity is increase with increasing of applied voltage. The dc conductivity has been measured for bulk polyaniline pure and doped in the form of compressed pellet with evaporated Ohmic Al electrodes in temperature range (303-423) K. The Eav energy of the thermal rate process of the electrical conductivity was determined. The results indicate that the dc conductivity of doped samples are two or three orders of magnitude higher by comparison with the pure sample and found that the increasing in conductivity of prepared samples with applied voltage is systematic.

Synthesis of C60-Doped Polyaniline Nanoshuttles

2011 ◽  
Vol 284-286 ◽  
pp. 1010-1013 ◽  
Author(s):  
Qi Guan Wang ◽  
Su Min Wang ◽  
Jian Ping Li ◽  
Hiroshi Moriyama
Keyword(s):  
Interfacial Reaction ◽  
Supramolecular Structure ◽  
Significant Interaction ◽  
Room Temperature ◽  
Oxidative Polymerization ◽  
Molar Ratio ◽  
Ammonium Peroxydisulfate ◽  
Vis Spectroscopy ◽  
Amorphous Powders ◽  
Doped Polyaniline

Polyaniline–C60nanoshuttle composites have been successfully synthesized by the oxidative polymerization of aniline with ammonium peroxydisulfate in the presence of C60using an interfacial reaction at room temperature, in which the molar ratio of oxidant to monomer was kept at 0.25:1. The influence of initial C60/aniline molar ratio on the supramolecular structure of the composites was studied. It was found that at low molar ratio (0.01:1) amorphous powders could be synthesized, while the as-synthesized products at the higher molar ratio (0.04:1) were shuttle-like superstructures. FTIR and UV-vis spectroscopy confirmed the presence of C60in the resultant nanocomposite and suggested significant interaction of polyaniline with C60. The evolution of supramolecular structure of polyaniline nanoshuttle–C60nanocomposites was discussed.

scholarly journals Heterostructural transformation of mesoporous silica–titania hybrids

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Navarut Paengjun ◽  
Kasimanat Vibulyaseak ◽  
Makoto Ogawa
Keyword(s):  
Heat Treatment ◽  
Mesoporous Silica ◽  
Structural Changes ◽  
Silanol Group ◽  
Photocatalytic Decomposition ◽  
Amorphous Precursor ◽  
Titania Content ◽  
Heat Treated ◽  
Anatase Nanoparticles ◽  
Lower Temperature

AbstractMesoporous silica (SBA-15 with the BJH pore size of 8 nm) containing anatase nanoparticles in the pore with two different titania contents (28 and 65 mass%), which were prepared by the infiltration of the amorphous precursor derived from tetraisopropyl orthotitanate into the pore, were heat treated in air to investigate the structural changes (both mesostructure of the SBA-15 and the phase and size of the anatase in the pore). The mesostructure of the mesoporous silica and the particle size of anatase unchanged by the heat treatment up to 800 °C. The heat treatment at the temperature higher than 1000 °C resulted in the collapse of the mesostructure and the growth of anatase nanoparticles as well as the transformation to rutile, while the transformation of anatase to rutile was suppressed especially for the sample with the lower titania content (28 mass%). The resulting mesoporous silica-anatase hybrids exhibited higher benzene adsorption capacity (adsorption from water) over those heated at lower temperature, probably due to the dehydroxylation of the silanol group on the pore surface. The photocatalytic decomposition of benzene in water by the present hybrid heated at 1100 °C was efficient as that by P25, a benchmark photocatalyst.

scholarly journals KARAKTERISTIK MIKROSTRUKTUR DAN FASA PADUAN Zr- 0,3%Nb-0,5%Fe-0,5%Cr PASCA PERLAKUAN PANAS DAN PENGEROLAN DINGIN

2015 ◽  
Vol 21 (2) ◽  
Author(s):  
Sungkono Sungkono ◽  
Masrukan Masrukan
Keyword(s):  
Crystal Structure ◽  
Heat Treatment ◽  
Corrosion Resistance ◽  
Cold Rolling ◽  
Retention Time ◽  
Cold Deformation ◽  
Grain Structure ◽  
Post Heat Treatment ◽  
Heat Treated ◽  
Fuel Elements

KARAKTERISTIK MIKROSTRUKTUR DAN FASA PADUAN Zr-0,3%Nb-0,5%Fe-0,5%Cr PASCA PERLAKUAN PANAS DAN PENGEROLAN DINGIN. Logam paduan Zr-Nb-Fe-Cr dikembangkan sebagai material kelongsong elemen bakar dengan fraksi bakar tinggi untuk reaktor daya maju. Dalam penelitian ini telah dibuat paduan Zr-0,3%Nb-0,5%Fe-0,5%Cr yang mendapat perlakuan panas pada temperatur 650 dan 750°C dengan waktu penahanan 1–2 jam. Tujuan penelitian adalah mendapatkan karakter paduan Zr-0,3%Nb-0,5%Fe-0,5%Cr pasca perlakuan panas dan pengerolan dingin yaitu mikrostruktur, struktur kristal dan fasa-fasa yang ada dalam paduan. Hasil penelitian menunjukkan bahwa paduan Zr-0,3%Nb-0,5%Fe-0,5%Cr pasca perlakuan panas (650ºC, 1-2 jam) mempunyai struktur butir ekuiaksial dengan ukuran butir bertambah besar seiring dengan bertambahnya waktu penahanan. Sementara itu, pasca perlakuan panas (750ºC, 1-2 jam) terjadi perubahan mikrostruktur paduan dari butir ekuiaksial dan kolumnar menjadi butir ekuiaksial lebih besar. Paduan Zr-0,3%Nb-0,5%Fe-0,5%Cr pasca perlakuan panas (650°C, 1 jam) dan (750°C, 1 jam) tidak dapat dirol dingin dengan reduksi tebal 5 – 10%, sedangkan pasca perlakuan panas (650ºC, 2 jam) dan (750°C, 1.5-2 jam) mampu menerima deformasi dingin dengan reduksi ketebalan 5-10% tanpa mengalami keretakan. Senyawa Zr2Fe, ZrCr2 dan FeCr teridentifikai dari hasil uji kristalografi paduan Zr-0,3%Nb-0,5%Fe-0,5%Cr. MICROSTRUCTURE AND PHASE CHARACTERISTICSOF Zr-0.3%Nb-0.5%Fe-0.5%Cr ALLOY POST HEAT TREATMENT AND COLD ROLLING. Zr-Nb-Fe-Cr alloys was developed as fuel elements cladding with high burn up for advanced power reactors. In this research has been made of Zr-0.3% Nb-0.5% Fe-0.5% Cr alloy were heat treated with varying temperatures at650 and 750°C for 1 until 2 hours. The objectives of this research was to obtain the character of Zr-0.3% Nb-0.5% Fe-0.5% Cr alloy post heat treatment and cold rolling, microstructure nomenclature, crystal structure and phases that presents in the alloy. The results of this experiment showed that the microstructures of Zr-0.3% Nb-0.5% Fe-0.5% Cr alloy post heat treatment (650ºC, 1-2 hours) had equiaxial grain structure with an enlarged size with increasing of the retention time. Meanwhile, post heat treatment (750°C, 1-2 hours) occurred the microstructures evolution of alloy from equiaxial and columnar became equiaxial and columnar relatively large, and subsequently became the larger equiaxial grains. Zr-0.3% Nb-0.5% Fe-0.5% Cr alloy post heat treatment (650°C, 2 h) and (750°C, 1.5-2 hours) can undergo cold deformation without cracking when thickness reduction between 5 to 10%.The phases formation of Zr2Fe, ZrCr2 and FeCr compounds can improve the mechanical strength and the corrosion resistance of Zr-0.3% Nb-0.5% Fe-0.5% Cr alloy.

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