scholarly journals Synthesis and Characterization of Hollow-Sphered Poly(N-methyaniline) for Enhanced Electrical Conductivity Based on the Anionic Surfactant Templates and Doping

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1023
Author(s):  
Chatrawee Direksilp ◽  
Anuvat Sirivat
Keyword(s):  
Thermal Stability ◽  
Electrical Conductivity ◽  
Doping Level ◽  
Anionic Surfactants ◽  
Sodium Dodecylsulfate ◽  
Sem Images ◽  
Dioctyl Sodium Sulfosuccinate ◽  
Surfactant Templates ◽  
Particle Shapes

Poly(N-methylaniline) (PNMA) is a polyaniline derivative with a methyl substituent on the nitrogen atom. PNMA is of interest owing to its higher solubility in organic solvents when compared to the unsubstituted polyaniline. However, the electrical conductivity of polyaniline derivatives suffers from chemical substitution. PNMA was synthesized via emulsion polymerization using three different anionic surfactants, namely sodium dodecylsulfate (SDS), sodium dodecylbenzenesulfonate (SDBS), and dioctyl sodium sulfosuccinate (AOT). The effects of surfactant structures and concentrations on electrical conductivity, doping level, crystallinity, morphology, and thermal stability were investigated. The re-doping step using perchloric acid (HClO4) as a dopant was sequentially proceeded to enhance electrical conductivity. PNMA synthesized in SDBS at five times its critical micelle concentration (CMC) demonstrated the highest electrical conductivity, doping level, and thermal stability among all surfactants at identical concentrations. Scanning electron microscopy (SEM) images revealed that the PNMA particle shapes and sizes critically depended on the surfactant types and concentrations, and the doping mole ratios in the re-doping step. The highest electrical conductivity of 109.84 ± 20.44 S cm−1 and a doping level of 52.45% were attained at the doping mole ratio of 50:1.

Improvement of Electrical Conductivity of Polyurethane/Polypyrrole Blends by Graphene

2020 ◽  
Vol 831 ◽  
pp. 122-126
Author(s):  
Pafun Janpoung ◽  
Prasit Pattananuwat ◽  
Pranut Potiyaraj
Keyword(s):  
Thermal Stability ◽  
Electrical Conductivity ◽  
Fourier Transform ◽  
Graphene Oxide ◽  
Controlled Synthesis ◽  
Sem Images ◽  
Thermogravimetric Analyzer ◽  
Solution Blending ◽  
Blending Process ◽  
Scanning Electron

Polyurethane (TPU)/polypyrrole (PPy) blends were successfully prepared by the solution blending process with different contents of reduce graphene oxide (rGO). The controlled synthesis of PPy/rGO composites was reported by varying graphene contents of 10, 20, 30 and 40% w/v. Fourier transform infrared (FTIR) and Scanning electron microscope (SEM) were used to characterize their structures and morphologies. The SEM images show the growing of PPy along the surface of graphene. FTIR illustrated that the PPy/rGO composites were in the doped state. The electrical conductivity of PPy/rGO composites with the concentration of graphene at 40% was about 30 times higher than that of pure PPy. Thermogravimetric analyzer (TGA) thermograms indicated that the PPy/rGO composites have better thermal stability than pure PPy.

AN EXPERIMENTAL STUDY ON MICROSTRUCTURE OF TUNGSTEN ALLOYS

2019 ◽  
Vol 27 (07) ◽  
pp. 1950169 ◽  
Author(s):  
E. DEMIR ◽  
M. N. MIRZAYEV ◽  
A. B. TUĞRUL ◽  
B. A. ABDURAKHIMOV ◽  
S. İ. KARAASLAN
Keyword(s):  
Thermal Stability ◽  
Weight Loss ◽  
High Temperatures ◽  
Microstructural Characterization ◽  
Sem Images ◽  
Argon Gas ◽  
Gas Desorption ◽  
Gas Atmosphere ◽  
Thermal Stability Of

The aim of this study is to provide information about microstructural and thermal properties of tungsten-based composites. Phase composition and microstructural characterization of tungsten composites were performed using X-ray diffractometer (XRD), Scanning Electron Microscopy (SEM), and Raman Spectroscopy. SEM images revealed the distribution of tungsten (W), vanadium carbide (VC) and graphite (C) powders in the tungsten matrix. The Raman spectra showed two major peaks, which are recorded at 1331 (vs) cm−1, and 1583 (vs) cm−1. These bands can be attributed to disorder graphite (D) and graphite (G). Thermogravimetric analysis (TGA) measurements were performed to determine the weight loss and thermal stability of the tungsten-based composites under argon gas atmosphere and at high temperatures. TGA measurements were performed to determine weight loss and thermal stability of tungsten-based composites under argon gas atmosphere and at high temperatures. The TG curve showed a slight weight loss in this temperature range. Mass loss is thought to be due to oxidation and gas desorption of materials.

scholarly journals Physical properties characterization of Natural Protein Fibre Peacock Feather Barbs

2017 ◽  
Author(s):  
Sekhar Das ◽  
Seiko Jose ◽  
Pintu Pandit
Keyword(s):  
Thermal Stability ◽  
Vertical Structure ◽  
Average Length ◽  
X Ray Diffraction ◽  
Colour Intensity ◽  
Sem Images ◽  
X Ray ◽  
Natural Protein ◽  
Mechanical Characterisation

AbstractIn the present study, the barbs of peacock feather were subjected to its physio-mechanical characterisation. Various properties of barbs viz., bundle strength, diameter, moisture regain, thermal stability, X-ray diffraction, colour intensity and FTIR was studied according standard analytical methods. The surface morphology of the barbs was examined using SEM images. The results indicate that the barb is a hollow vertical structure made up of protein. The average length and diameter of the barb was found to be 45 mm and 82 μm respectively. The FTIR study confirms the presence of characteristic peaks for protein, related to the keratinous material. The barbs seem to be semi-crystalline in nature, as indicated by X-ray study.

scholarly journals Characterization of Bio-Adsorbents Produced by Hydrothermal Carbonization of Corn Stover: Application on the Adsorption of Acetic Acid from Aqueous Solutions

Energies ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 8154
Author(s):  
Maria Elizabeth Gemaque Costa ◽  
Fernanda Paula da Costa Assunção ◽  
Tiago Teribele ◽  
Lia Martins Pereira ◽  
Douglas Alberto Rocha de Castro ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Acetic Acid ◽  
Aqueous Solutions ◽  
Carbon Content ◽  
Corn Stover ◽  
Elemental Analysis ◽  
Hydrothermal Carbonization ◽  
Process Temperature ◽  
Sem Images

In this work, the influence of temperature on textural, morphological, and crystalline characterization of bio-adsorbents produced by hydrothermal carbonization (HTC) of corn stover was systematically investigated. HTC was conducted at 175, 200, 225, and 250 °C, 240 min, heating rate of 2.0 °C/min, and biomass-to-H2O proportion of 1:10, using a reactor of 18.927 L. The textural, morphological, crystalline, and elemental characterization of hydro-chars was analyzed by TG/DTG/DTA, SEM, EDX, XRD, BET, and elemental analysis. With increasing process temperature, the carbon content increased and that of oxygen and hydrogen diminished, as indicated by elemental analysis (C, N, H, and S). TG/DTG analysis showed that higher temperatures favor the thermal stability of hydro-chars. The hydro-char obtained at 250 °C presented the highest thermal stability. SEM images of hydro-chars obtained at 175 and 200 °C indicated a rigid and well-organized fiber structure, demonstrating that temperature had almost no effect on the biomass structure. On the other hand, SEM images of hydro-chars obtained at 225 and 250 °C indicated that hydro-char structure consists of agglomerated micro-spheres and heterogeneous structures with nonuniform geometry (fragmentation), indicating that cellulose and hemi-cellulose were decomposed. EDX analysis showed that carbon content of hydro-chars increases and that of oxygen diminish, as process temperature increases. The diffractograms (XRD) identified the occurrence of peaks of higher intensity of graphite (C) as the temperature increased, as well as a decrease of peaks intensity for crystalline cellulose, demonstrating that higher temperatures favor the formation of crystalline-phase graphite (C). The BET analysis showed 4.35 m2/g surface area, pore volume of 0.0186 cm3/g, and average pore width of 17.08 μm. The solid phase product (bio-adsorbent) obtained by hydrothermal processing of corn stover at 250 °C, 240 min, and biomass/H2O proportion of 1:10, was activated chemically with 2.0 M NaOH and 2.0 M HCl solutions to investigate the adsorption of CH3COOH. The influence of initial acetic acid concentrations (1.0, 2.0, 3.0, and 4.0 mg/mL) was investigated. The kinetics of adsorption were investigated at different times (30, 60, 120, 240, 480, and 960 s). The adsorption isotherms showed that chemically activated hydro-chars were able to recover acetic acid from aqueous solutions. In addition, activation of hydro-char with NaOH was more effective than that with HCl.

Characterization of Electrical Conductivity of Carbon Nanotube Composites

2014 ◽  
Author(s):  
Shen Gong ◽  
Zhenghong Zhu ◽  
Jun Li
Keyword(s):  
Electrical Conductivity ◽  
Surface Modification ◽  
Polymer Composites ◽  
Structural Integrity ◽  
Epoxy Composites ◽  
Sem Images ◽  
Low Viscosity ◽  
Before And After ◽  
Nanotube Composites

This work investigated and characterized the electrical conductivity of carbon nanotubes (CNT)/polymer composites. Surface modification has been applied to improve the homogeneous dispersion of MWCNTs in epoxy. After treatment, MWCNTs were mixed into low viscosity epoxy matrix at room temperature. Dispersion and structural integrity of MWCNTs before and after surface modification were examined by SEM images. The dispensability of treated MWCNTs and electrical conductivity of nanocomposites are evaluated and also compared with MWCNTs/polymer composites in literature prepared using the same commercial MWCNTs. The electrical conductivity of MWCNTs and MWCNTs/epoxy composites were evaluated by the four-point probe method. The results of electrical property will lay a foundation for establishing the relationship between electrical resistance and strain of MWCNTs/epoxy composites. The results also confirm that reducing CNT agglomerate size can greatly improve the electrical conductivity of composite and decrease the percolation threshold.

Effect of the structure of cellulose acetate membranes on their permeability, electrical conductivity and rejection

1990 ◽  
Vol 55 (12) ◽  
pp. 2933-2939 ◽  
Author(s):  
Hans-Hartmut Schwarz ◽  
Vlastimil Kůdela ◽  
Klaus Richau
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Cellulose Acetate ◽  
Reverse Osmosis ◽  
Water Flux ◽  
Cellulose Acetate Membrane ◽  
Structure Parameters ◽  
Dc Electrical Conductivity ◽  
Cellulose Acetate Membranes

Ultrafiltration cellulose acetate membrane can be transformed by annealing into reverse osmosis membranes (RO type). Annealing brings about changes in structural properties of the membranes, accompanied by changes in their permeability behaviour and electrical properties. Correlations between structure parameters and electrochemical properties are shown for the temperature range 20-90 °C. Relations have been derived which explain the role played by the dc electrical conductivity in the characterization of rejection ability of the membranes in the reverse osmosis, i.e. rRO = (1 + exp (A-B))-1, where exp A and exp B are statistically significant correlation functions of electrical conductivity and salt permeation, or of electrical conductivity and water flux through the membrane, respectively.

scholarly journals The Preparation and Characterization of Chitosan-Based Hydrogels Cross-Linked by Glyoxal

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2449
Author(s):  
Beata Kaczmarek-Szczepańska ◽  
Olha Mazur ◽  
Marta Michalska-Sionkowska ◽  
Krzysztof Łukowicz ◽  
Anna Maria Osyczka
Keyword(s):  
Thermal Stability ◽  
Tannic Acid ◽  
Dental Pulp ◽  
Blood Compatibility ◽  
Dental Pulp Cells ◽  
Preliminary Assessment ◽  
Human Dental Pulp Cells ◽  
Human Dental Pulp ◽  
Pulp Cells

In this study, hydrogels based on chitosan cross-linked by glyoxal have been investigated for potential medical applications. Hydrogels were loaded with tannic acid at different concentrations. The thermal stability and the polyphenol-releasing rate were determined. For a preliminary assessment of the clinical usefulness of the hydrogels, they were examined for blood compatibility and in the culture of human dental pulp cells (hDPC). The results showed that after immersion in a polyphenol solution, chitosan/glyoxal hydrogels remain nonhemolytic for erythrocytes, and we also did not observe the cytotoxic effect of hydrogels immersed in tannic acid (TA) solutions with different concentration. Tannic acid was successfully released from hydrogels, and its addition improved material thermal stability. Thus, the current findings open the possibility to consider such hydrogels in clinics.

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