scholarly journals Microwave heating oxidative stabilization of KMnO4 modified polyacrylonitrile-based carbon fiber precursor

2021 ◽  
Author(s):  
Cheng Zhang ◽  
Jianhua Liu
Keyword(s):  
Mechanical Properties ◽  
Bulk Density ◽  
Photoelectron Spectroscopy ◽  
Tensile Modulus ◽  
Fiber Surface ◽  
Thermal Stabilization ◽  
Oxidation Reactions ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Stability

Abstract Dielectric property, bulk density, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), wide angle X-ray diffraction (WAXD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and mechanical properties were analyzed. PAN fibers (PFs) are polar materials, and the dielectric constant of KMnO4 modification fibers (Mn-PFs) is reduced. The bulk density of Mn-PFs under microwave stabilization (Mn-MSFs) is 0.04 g/cm3 higher than that of the microwave stabilized fibers (MSFs), shortening the value in one temperature zone. Compared with MSFs5, the stability of Mn-MSFs5 is improved by 10%, and the surface O content and O-containing functional groups are improved. The (002) crystal plane diffraction peak of Mn-MSFs5 is higher than that of MSFs5, and it has a higher stabilized structure. Moreover, after stabilization, the Mn element does not exist on the fiber surface and does not affect the structure of the stabilized fiber. The fineness of Mn-MSFs5 is 1.07 dtex, tensile strength is 1.52 cN/dtex, tensile modulus is 59.3 cN/dtex and elongation at break is 13.5%. It has excellent mechanical properties. In addition, a structural transformation of the thermal stabilization process is proposed, that is, the cyclization reaction first occurs, and then the dehydrogenation and oxidation reactions are performed.

scholarly journals Copper Containing Glass-Based Bone Adhesives for Orthopaedic Applications: Glass Characterization and Advanced Mechanical Evaluation

2020 ◽  
Author(s):  
Sahar. Mokhtari ◽  
Anthony.W. Wren
Keyword(s):  
Mechanical Properties ◽  
Photoelectron Spectroscopy ◽  
Structural Changes ◽  
Viscoelastic Behavior ◽  
Polymer Chains ◽  
Nano Particles ◽  
X Ray Diffraction ◽  
X Ray ◽  
Compression Data

AbstractThis study addresses issues with currently used bone adhesives, by producing novel glass based skeletal adhesives through modification of the base glass composition to include copper (Cu) and by characterizing each glass with respect to structural changes. Bioactive glasses have found applications in fields such as orthopedics and dentistry, where they have been utilized for the restoration of bone and teeth. The present work outlines the formation of flexible organic-inorganic polyacrylic acid (PAA) – glass hybrids, commercial forms are known as glass ionomer cements (GICs). Initial stages of this research will involve characterization of the Cu-glasses, significant to evaluate the properties of the resulting adhesives. Scanning electron microscopy (SEM) of annealed Cu glasses indicates the presence of partial crystallization in the glass. The structural analysis of the glass using Raman suggests the formation of CuO nanocrystals on the surface. X-ray diffraction (XRD) pattern and X-ray photoelectron spectroscopy (XPS) further confirmed the formation of crystalline CuO phases on the surface of the annealed Cu-glass. The setting reaction was studied using Fourier transform infrared spectroscopy (ATR-FTIR). The mechanical properties of the Cu containing adhesives exhibited gel viscoelastic behavior and enhanced mechanical properties when compared to the control composition. Compression data indicated the Cu glass adhesives were efficient at energy dissipation due to the reversible interactions between CuO nano particles and PAA polymer chains.

scholarly journals Structure-Dependent Mechanical Properties of ALD-Grown Nanocrystalline BiFeO3Multiferroics

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Anna Majtyka ◽  
Anna Nowak ◽  
Benoît Marchand ◽  
Dariusz Chrobak ◽  
Mikko Ritala ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Photoelectron Spectroscopy ◽  
Present Report ◽  
Structural Evolution ◽  
Atomic Layer ◽  
Grazing Incidence ◽  
X Ray Diffraction ◽  
X Ray ◽  
Layer Deposition ◽  
Pertinent Information

The present paper pertains to mechanical properties and structure of nanocrystalline multiferroic BeFiO3(BFO) thin films, grown by atomic layer deposition (ALD) on the Si/SiO2/Pt substrate. The usage of sharp-tip-nanoindentation and multiple techniques of structure examination, namely, grazing incidence X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and energy dispersive X-ray spectrometry, enabled us to detect changes in elastic properties(95 GPa≤E≤118 GPa)and hardness(4.50 GPa≤H≤7.96 GPa)of BFO after stages of annealing and observe their relation to the material’s structural evolution. Our experiments point towards an increase in structural homogeneity of the samples annealed for a longer time. To our best knowledge, the present report constitutes the first disclosure of nanoindentation mechanical characteristics of ALD-fabricated BeFiO3, providing a new insight into the phenomena that accompany structure formation and development of nanocrystalline multiferroics. We believe that our systematic characterization of the BFO layers carried out at consecutive stages of their deposition provides pertinent information which is needed to control and optimize its ALD fabrication.

An Heterocyclic Aromatic Polymer and Its Mechanical Properties

1988 ◽  
Vol 134 ◽  
Author(s):  
Seiichi Mukai ◽  
S. Nozawa ◽  
M. Kimura ◽  
T. Tayama
Keyword(s):  
Mechanical Properties ◽  
Block Copolymers ◽  
Tensile Modulus ◽  
Wide Angle ◽  
X Ray Diffraction ◽  
Dramatic Decrease ◽  
Pyromellitic Acid ◽  
X Ray ◽  
Molecular Composites ◽  
Heterocyclic Polymer

ABSTRACTA novel polyimide-based heterocyclic polymer, polyimide benzobisthiazole (PIBT), was prepared from diaminophenylene benzobisthiazole (DAPBT) and pyromellitic acid dianhydride (PMDA). Fibers with tensile modulus of 220 GPa were obtained from PIBT; this modulus value is consistent with the 430 GPa modulus determined by wide-angle x-ray diffraction (WAXD) analysis. Unoriented isotropic films exhibited significantly lower modulus values in the range of 10 GPa. Block copolymers of PIBT with thermoplastic segments were synthesized in an effort to prepare molecular composites. These materials showed a dramatic decrease in melt viscosity and had modulus values lower than observed in isotropic PIBT films.

scholarly journals Influence of the Double Bond LDH Clay on the Exfoliation / Intercalation Mechanism of Polyacrylamide Nanocomposite Hydrogels

2018 ◽  
Vol 55 (3) ◽  
pp. 263-268
Author(s):  
Ionut Cristian Radu ◽  
Eugeniu Vasile ◽  
Celina Maria Damian ◽  
Horia Iovu ◽  
Paul Octavian Stanescu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Photoelectron Spectroscopy ◽  
Biomedical Applications ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nanocomposite Hydrogels ◽  
Transmission Electron ◽  
Double Hydroxides ◽  
Classical Cross ◽  
Chemical Cross Linking

The paper focuses on the obtaining of novel nanocomposite hydrogels based on polyacrylamide and layered double hydroxides (LDHs) modified with double bonds. The modification of LDH clay was investigated by FTIR, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analyses. Mechanical properties of the nanocomposite hydrogels were employed by compression and rheological measurements. The formation of exfoliated and intercalated structures was evidenced in transmission electron microscopy (TEM). Chemical cross-linking of hydrogels using both classical cross-linker and modified clay was an efficient method to improve the mechanical properties of novel nanocomposite hydrogels. These hydrogels with improved mechanical properties could be further tested for biomedical applications such as tissue engineering.

Tribological Properties of DLC Coating with Various Zr Target Current

2017 ◽  
Vol 739 ◽  
pp. 23-29
Author(s):  
Wen Hsien Kao
Keyword(s):  
Mechanical Properties ◽  
Tribological Properties ◽  
Photoelectron Spectroscopy ◽  
Wear Depth ◽  
X Ray Diffraction ◽  
Properties Of Coatings ◽  
X Ray ◽  
Dlc Coating ◽  
Unbalanced Magnetron ◽  
G Ratio

The main purpose of this study is to research the tribological properties and mechanical properties of diamond-like carbon coating (DLC) used unbalanced magnetron sputtering system (UBMS). The objective is influence of various Zr target current on the properties of coatings, current from 0.0 A to 0.5 A. The cross-section morphology was observed by field emission scanning electron microscopy (FE-SEM). With the increase of the Zirconium targets current, the quantity contained of the Zirconium increases. Raman spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were employed to analyze the microstructure properties of the coatings. The nanoindentation tester was used to measure the mechanical properties. Furthermore, the wear tests were achieved through the Schwingung Reibung and Verschliess (SRV) reciprocating wear tester under dry condition. The DLC coating was deposited used 0.4 A Zr target current possessed the lowest I(D)/I(G) ratio, the highest sp3 content and highest hardness. The DLC coating (0.4A) also displayed excellent tibological properties including the lowest friction coefficient, and wear depth.

Preparation of Pd/GO/Cu Electrode and Its Electrochemical Degradation for 2,4-Dichlorophenol

2020 ◽  
Vol 20 (6) ◽  
pp. 3604-3609
Author(s):  
Jian Zhang ◽  
Yuting Jiang ◽  
Bing Wang ◽  
Lanhe Zhang ◽  
Zheng Li ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Water Environment ◽  
Constant Current ◽  
Surface Element ◽  
Impregnation Method ◽  
Electrochemical Degradation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Preparation Conditions ◽  
The Stability

Chlorinated aromatic compounds (CACs) are a class of persistent organic pollutants, which have serious damage to water environment due to their own stable structure. But a good many of CACs were abandoned because of their tremendous yields and wide applications, so it is urgent to find the effective degradation methods for CACs. The electrochemical method is supposed to be a simple, environmentally friendly and effective pathway to degrade CACs. In this paper, a Pd/GO/Cu composite electrode was prepared by a combination of impregnation method and constant current electrodeposition method, which showed good electrochemical degradation efficiency for the 2,4-dichlorophenol. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to characterize the surface structure, functional group composition, crystal structure and surface element valence of the electrode. Moreover, the stability of the electrode was investigated, and the preparation conditions of the electrode were optimized.

scholarly journals Synthesis and Characterization of Graphene Oxide/Chitosan Composite Aerogels with High Mechanical Performance

Polymers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 777 ◽  
Author(s):  
Yang Gong ◽  
Yingchun Yu ◽  
Huixuan Kang ◽  
Xiaohong Chen ◽  
Hao Liu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Graphene Oxide ◽  
Photoelectron Spectroscopy ◽  
Mechanical Performance ◽  
X Ray Diffraction ◽  
X Ray ◽  
Composite Aerogels ◽  
Mercury Porosimeter ◽  
Chitosan Composite

Chitosan, a semi-crystalline biomolecule, has attracted wide attention due to its high synthesis flexibility. In this study, to improve the mechanical properties of chitosan aerogels (CSAs), graphene oxide (GO) was extracted and introduced into chitosan aerogels as fillers. The porous CSAs/GO composite aerogels were fabricated by an environmentally friendly freeze-drying process with different GO contents (0, 0.5, 1.0, 1.5, wt.%). The characteristics of the CSAs/GO were investigated by scanning electron microscopy (SEM), mechanical measurements and mercury porosimeter. The crystallinity of samples was characterized by X-ray diffraction (XRD). The mechanism of the effect of graphene oxide on chitosan was studied by Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The results show that the microstructure of the samples is developed in the network structure. The porosity of CSAs/GO aerogels is as high as 87.6%, and the tensile strength of the films increased from 6.60 MPa to 10.56 MPa with the recombination of graphene oxide. The crystallinity (CrI) of composite aerogels increased from 27% to 81%, which indicates that graphene oxide improves the mechanical properties of chitosan by chemical crosslinking.

scholarly journals FeCrAlloy Monoliths Coated with Ni/Al2O3 Applied to the Low-Temperature Production of Ethylene

Catalysts ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 291 ◽  
Author(s):  
Paula Brussino ◽  
Juan Bortolozzi ◽  
Oihane Sanz ◽  
Mario Montes ◽  
María Ulla ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Catalyst Layer ◽  
X Ray Diffraction ◽  
Ethane Conversion ◽  
X Ray ◽  
Structured Catalyst ◽  
Temperature Programmed ◽  
Ni Species ◽  
The Stability ◽  
Geometric Surface

This paper investigates the oxidative dehydrogenation of ethane to produce ethylene at low temperatures (500 °C) in metallic structured substrates. To check this point, the FeCrAlloy® monoliths with different channel sizes (289–2360 cpsi) were prepared. The monoliths were coated with a Ni/Al2O3 catalyst (by washcoating of alumina and the latter nickel impregnation) and characterized by Scanning Electron Microscopy and Energy-Dispersive X-ray analysis (SEM-EDX), Temperature-Programmed Reduction (TPR), X-ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS). The catalytic results showed that all monoliths coated with ~300 mg of catalyst presented similar ethane conversion (15%) at 450 °C. However, the lowest selectivity to ethylene was found for the monolith with the lower channel size and the higher geometric surface area, where a heterogeneous catalyst layer with Ni enriched islands was generated. Therefore, it can be said that the selectivity to ethylene is linked to the distribution of Ni species on the support (alumina). Nevertheless, in all cases the selectivity was high (above 70%). On the other hand, the stability in reaction tests of one of the coated monoliths was done. This structured catalyst proved to be more stable under reaction conditions than the powder catalyst, with an initial slight drop in the first 8 h but after that, constant activity for the 152 h left.

Preparation and characterization of a copper@polyimide core–shell structure via an in situ induction/imidization route

2016 ◽  
Vol 29 (5) ◽  
pp. 569-574
Author(s):  
Haoran Zhou ◽  
Dexin Wang ◽  
Chunyan Qu ◽  
Changwei Liu ◽  
Shanshan Mao
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Amic Acid ◽  
Core Shell ◽  
Oxidation Reactions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Pure Cu

Based on the combination of an in situ induction and imidization method for improving the interface bonding of an inorganic material and a polymer, copper@polyimide (Cu@PI) core–shell composite particles have been successfully prepared from poly(amic acid) ammonium salts (PAAS) and a Cu complex via a simple solvothermal process. The structures and the morphologies of the samples were characterized by X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy and transmission electron microscopy (TEM), respectively. It was found that PAAS formed PI via a thermal imidization and subsequently precipitated in the solvent. Through crystallization induction, it then successfully coated on the surface of the formed Cu particles. Based on thermo gravimetric analyses curves and due to no Cu oxidation reactions taking place in the core coated with high-temperature-resistant PI, the weight increase was determined to be 106.4%, instead of up to 124.0% in samples consisting of pure Cu.

Nanostructure and mechanical properties of WC–SiC thin films

2002 ◽  
Vol 17 (12) ◽  
pp. 3163-3167 ◽  
Author(s):  
Jose L. Endrino ◽  
James E. Krzanowski
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
Photoelectron Spectroscopy ◽  
Nanocrystalline Structure ◽  
Amorphous Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Hardness Increase ◽  
Carbide Content

The mechanical properties of WC–SiC thin films deposited by dual radio frequency magnetron sputtering were investigated. The films were characterized by x-ray photoelectron spectroscopy, x-ray diffraction (XRD), and transmission electron microscopy (TEM) to evaluate the details of the microstructure and degree of amorphization. The results indicate that small additions of SiC (<25%) can significantly increase hardness compared to a pure WC film, but higher SiC contents do not strongly affect hardness. XRD studies show the SiC had a disordering effect. TEM results showed that WC films had coarse porous structure, but films with a low silicon carbide content (approximately 10 to 25 at%) had a denser nanocrystalline structure. Samples with greater than 25% SiC were amorphous. The initial hardness increase at lower SiC contents correlated well with the observed densification, but the transition to an amorphous structure did not strongly affect hardness.

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