scholarly journals Synthesis, Characterization, and CO2/N2 Separation Performance of POEM-g-PAcAm Comb Copolymer Membranes

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 177
Author(s):  
Byeong Ju Park ◽  
Na Un Kim ◽  
Chang Soo Lee ◽  
Jong Hak Kim
Keyword(s):  
Spectroscopic Studies ◽  
Amorphous Structure ◽  
Proton Nuclear Magnetic Resonance ◽  
Separation Performance ◽  
Scanning Calorimetry ◽  
Free Standing ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
Comb Copolymer ◽  
Separation Performances

Alcohol-soluble comb copolymers were synthesized from rubbery poly(oxyethylene methacrylate) (POEM) and glassy polyacrylamide (PAcAm) via economical and facile free-radical polymerization. The synthesis of comb copolymers was confirmed by Fourier-transform infrared and proton nuclear magnetic resonance spectroscopic studies. The bicontinuous microphase-separated morphology and amorphous structure of comb copolymers were confirmed by wide-angle X-ray scattering, differential scanning calorimetry, and transmission electron microscopy. With increasing POEM content in the comb copolymer, both CO2 permeability and CO2/N2 selectivity gradually increased. A mechanically strong free-standing membrane was obtained at a POEM:PAcAm ratio of 70:30 wt%, in which the CO2 permeability and CO2/N2 selectivity reached 261.7 Barrer (1 Barrer = 10−10 cm3 (STP) cm cm−2 s−1 cmHg−1) and 44, respectively. These values are greater than those of commercially available Pebax and among the highest separation performances reported previously for alcohol-soluble, all-polymeric membranes without porous additives. The high performances were attributed to an effective CO2-philic pathway for the ethylene oxide group in the rubbery POEM segments and prevention of the N2 permeability by glassy PAcAm chains.

scholarly journals Study on Structure, Thermal Behavior, and Viscoelastic Properties of Nanodiamond-Reinforced Poly (vinyl alcohol) Nanocomposites

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1426
Author(s):  
Tomáš Remiš ◽  
Petr Bělský ◽  
Tomáš Kovářík ◽  
Jaroslav Kadlec ◽  
Mina Ghafouri Azar ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Analysis ◽  
Single Step ◽  
Poly Vinyl Alcohol ◽  
Scanning Calorimetry ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
Primary Particles ◽  
Solution Casting Method ◽  
Average Size

In this work, advanced polymer nanocomposites comprising of polyvinyl alcohol (PVA) and nanodiamonds (NDs) were developed using a single-step solution-casting method. The properties of the prepared PVA/NDs nanocomposites were investigated using Raman spectroscopy, small- and wide-angle X-ray scattering (SAXS/WAXS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA). It was revealed that the tensile strength improved dramatically with increasing ND content in the PVA matrix, suggesting a strong interaction between the NDs and the PVA. SEM, TEM, and SAXS showed that NDs were present in the form of agglomerates with an average size of ~60 nm with primary particles of diameter ~5 nm. These results showed that NDs could act as a good nanofiller for PVA in terms of improving its stability and mechanical properties.

Nitroxide-mediated graft copolymerization of styrene from cellulose and its polymer/montmorillonite nanocomposite

2018 ◽  
Vol 51 (5) ◽  
pp. 473-489 ◽  
Author(s):  
Mojtaba Abbasian ◽  
Mojtaba Bakhshi ◽  
Mehdi Jaymand ◽  
Saber Ghasemi Karaj-Abad
Keyword(s):  
Electron Microscopy ◽  
Graft Copolymerization ◽  
Proton Nuclear Magnetic Resonance ◽  
Scanning Calorimetry ◽  
Structural Morphology ◽  
Produce Cell ◽  
Solution Intercalation ◽  
Transmission Electron ◽  
Electron Microscopy Analysis ◽  
Grafting From

Nitroxide-mediated polymerization was successfully employed for well-defined graft copolymerization of styrene (St) monomer from cellulose (Cell) backbone. For this purpose, Cell was acylated by 2-bromoisobutyryl bromide, and then 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) was immobilized onto Cell backbone using a nucleophilic substitution reaction to produce Cell-TEMPO macroinitiator. Afterward, St monomer was grafted onto Cell backbone through “grafting from” technique. The successful synthesis of Cell- g-polystyrene (PSt) copolymer was confirmed using Fourier transform infrared and proton nuclear magnetic resonance spectroscopies and scanning electron microscopy analysis. Finally, Cell- g-PSt/montmorillonite nanocomposite was fabricated through solution intercalation approach. The thermal properties and structural morphology of the resultant nanocomposite were investigated using thermogravimetric analysis and differential scanning calorimetry and transmission electron microscopy, respectively.

Understanding the Compromise between Strength and Exfoliation Corrosion in High Strength 7000 Alloys

2006 ◽  
Vol 519-521 ◽  
pp. 455-460 ◽  
Author(s):  
T. Marlaud ◽  
B. Baroux ◽  
Alexis Deschamps ◽  
J.L. Chemin ◽  
C. Hénon
Keyword(s):  
Corrosion Resistance ◽  
Volume Fraction ◽  
High Strength ◽  
Precipitate Size ◽  
Scanning Calorimetry ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
Size Evolution ◽  
Zn Content ◽  
Zn Alloy

The microstructural evolution has been investigated in three alloys of the 7000 series possessing increasing zinc contents by combining small-angle X-ray scattering, differential scanning calorimetry and transmission electron microscopy, in order to gain understanding on the evolution of the compromise between yield strength and corrosion resistance. We show that the three materials show qualitatively identical precipitation sequences; however the precipitated volume fraction is shown to increase in parallel to the Zn content. Moreover, the precipitate size evolution is faster in the high Zn alloy. The precipitate composition is inferred to vary in the three materials, and this difference is shown to explain the differences in calorimetric behavior, precipitation kinetics and corrosion resistance.

scholarly journals Crystallization Process and Microstructural Evolution of Melt Spun Al-RE-Ni-(Cu) Ribbons

Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 443
Author(s):  
Francisco G. Cuevas ◽  
Sergio Lozano-Perez ◽  
Rosa María Aranda ◽  
Raquel Astacio
Keyword(s):  
Crystallization Process ◽  
Primary Crystallization ◽  
Amorphous Structure ◽  
Intermetallic Phases ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
Melt Spun ◽  
The Stability

The crystallization process, both at the initial and subsequent stages, of amorphous Al88-RE4-Ni8 alloys (RE = Y, Sm and Ce) has been studied. Additionally, the consequences of adding 1 at.% Cu replacing Ni or Al were studied. The stability of the amorphous structure in melt spun ribbons was thermally studied by differential scanning calorimetry, with Ce alloys being the most stable. The effect of Cu to reduce the nanocrystal size during primary crystallization was analyzed by transmission electron microscopy. This latter technique and x-ray diffraction showed the formation of intermetallic phases at higher temperatures. A clear difference was observed for the Ce alloy, with a simpler sequence involving the presence of Al3Ni and Al11Ce3. However, for the Y and Sm alloys, a more complex evolution involving metastable ternary phases before Al19RE5Ni3 appears, takes place. The shape of the intermetallics changes from equiaxial in the Ce alloys to elongate for Y and Sm, with longer particles for Sm and, in general, when Cu is added to the alloy.

scholarly journals Aggregation behaviour of a single-chain, phenylene-modified bolalipid and its miscibility with classical phospholipids

2017 ◽  
Vol 13 ◽  
pp. 995-1007 ◽  
Author(s):  
Simon Drescher ◽  
Vasil M Garamus ◽  
Christopher J Garvey ◽  
Annette Meister ◽  
Alfred Blume
Keyword(s):  
Small Angle ◽  
Coupling Reaction ◽  
Lipid Vesicles ◽  
Single Chain ◽  
Scanning Calorimetry ◽  
X Ray Scattering ◽  
Aggregation Behaviour ◽  
Cross Coupling Reaction ◽  
Transmission Electron ◽  
Partially Miscible

In the present work, we describe the synthesis of a single-chain, phenylene-modified bolalipid with two phosphocholine headgroups, PC-C18pPhC18-PC, using a Sonogashira cross-coupling reaction as a key step. The aggregation behaviour was studied as a function of temperature using transmission electron microscopy (TEM), differential scanning calorimetry (DSC), Fourier-transform infrared (FTIR) spectroscopy, and small angle neutron scattering (SANS). We show that our new bolalipid self-assembles into nanofibres, which transform into flexible nanofibres at 27 °C and further to small elongated micelles at 45 °C. Furthermore, the miscibility of the bolalipid with bilayer-forming phosphatidylcholines (DMPC, DPPC, and DSPC) was investigated by means of DSC, TEM, FTIR, and small angle X-ray scattering (SAXS). We could show that the PC-C18pPhC18-PC is partially miscible with saturated phosphatidylcholines; however, closed lipid vesicles with an increased thermal stability were not found. Instead, bilayer fragments and disk-like aggregates are formed.

Amorphous Phase Formation and Heat Treating Evolution in Mechanically Alloyed Al-Ti Powders

2018 ◽  
Vol 772 ◽  
pp. 118-122
Author(s):  
Petr Urban ◽  
Eduardo Sanchez Caballero ◽  
Fatima Ternero ◽  
Francisco Javier Viña Reina ◽  
Francisco Gomez Cuevas
Keyword(s):  
Electron Microscopy ◽  
Microstructural Characterization ◽  
Heat Treating ◽  
High Energy ◽  
Amorphous Structure ◽  
Elemental Distribution ◽  
Mechanically Alloyed ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
Alloy Heat

This paper focuses on the microstructural characterization of Al25Ti75, Al37Ti63, Al50Ti50, Al63Ti37and Al75Ti25powders mixtures prepared by mechanical alloying (MA). The high-energy ball-milling, up to 75 h, of aluminium and titanium powders leads to a nanocrystalline or an amorphous structure. It is showed that a stable amorphous Al–Ti phase with uniform elemental distribution forms after 50 h of milling in Al50Ti50alloy. Heat treatment of the different alloys leads to the crystallization of AlTi3, AlTi, Al2Ti and Al3Ti intermetallic compounds. A comprehensive study by laser granulometry, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC) was carried out on the structure, surface morphology and thermal behaviour of the MA Al-Ti mixtures, both of milled and heat treated powders.

Microstructure and Chemistry of Annealed Al–Cu–Fe–Cr Quasicrystalline Approximant Coatings

2005 ◽  
Vol 20 (1) ◽  
pp. 176-182 ◽  
Author(s):  
M.J. Daniels ◽  
J.S. Zabinski ◽  
H. Wu ◽  
C.R.M. Grovenor ◽  
J.C. Bilello
Keyword(s):  
Grazing Incidence ◽  
Amorphous Structure ◽  
Spectroscopy Analysis ◽  
Columnar Growth ◽  
X Ray ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
Cr Film ◽  
Penetration Depths ◽  
Study Development

An as-deposited Al–Cu–Fe–Cr film was annealed in flowing argon to study development of a quasicrystalline approximant microstructure. Sputter profile x-ray photoemission spectroscopy analysis showed oxygen incorporation reached approximately 70 at.% at the surface of the film, declined monotonically, and stabilized at ∼10 at.% at a depth of 160 nm. Synchrotron grazing incidence x-ray scattering was used to probe the structure of the coating at various penetration depths by altering the angle of the incident x-ray beam. An amorphous structure was observed near the termination surface, which coexisted with a compressively strained crystalline aluminum. These phases were the dominant microstructure to a depth of 110 nm. Below 150 nm, the film was primarily O1 decagonal approximant. Cross-section transmission electron microscopy elucidated a columnar growth morphology with associated porosity in the interstices between the columns. The resulting development of the Al–Cu–Fe–Cr decagonal approximant coatings from the precursor is reported.

scholarly journals Alternating Gyroid Network Structure in an ABC Miktoarm Terpolymer Comprised of Polystyrene and Two Polydienes

Nanomaterials ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1497 ◽  
Author(s):  
Dimitrios Moschovas ◽  
Gkreti-Maria Manesi ◽  
Andreas Karydis-Messinis ◽  
George Zapsas ◽  
Konstantinos Ntetsikas ◽  
...  
Keyword(s):  
Network Structure ◽  
Morphological Characterization ◽  
Degree Of Polymerization ◽  
Scanning Calorimetry ◽  
X Ray ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
Three Phase ◽  
Microdomain Structure

The synthesis, molecular and morphological characterization of a 3-miktoarm star terpolymer of polystyrene (PS, M¯n = 61.0 kg/mol), polybutadiene (PB, M¯n = 38.2 kg/mol) and polyisoprene (PI, M¯n = 29.2 kg/mol), corresponding to volume fractions (φ) of 0.46, 0.31 and 0.23 respectively, was studied. The major difference of the present material from previous ABC miktoarm stars (which is a star architecture bearing three different segments, all connected to a single junction point) with the same block components is the high 3,4-microstructure (55%) of the PI chains. The interaction parameter and the degree of polymerization of the two polydienes is sufficiently positive to create a three-phase microdomain structure as evidenced by differential scanning calorimetry and transmission electron microscopy (TEM). These results in combination with small-angle X-ray scattering (SAXS) and birefringence experiments suggest a cubic tricontinuous network structure, based on the I4132 space group never reported previously for such an architecture.

scholarly journals In-situ TEM annealing of amorphous Fe-24at.%W coatings and the effect of crystallization on hardness

2020 ◽  
Vol 56 (5) ◽  
pp. 4006-4012
Author(s):  
Antonio Mulone ◽  
Inga Ennen ◽  
Andreas Hütten ◽  
Uta Klement
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Amorphous Structure ◽  
In Situ Tem ◽  
Amorphous Coating ◽  
Scanning Calorimetry ◽  
Plating Bath ◽  
Maximum Value ◽  
Transmission Electron

AbstractThis paper describes the crystallization which occurs upon annealing of an amorphous Fe-24at.%W coatings, electrodeposited from a glycolate-citrate plating bath. A combination of Differential Scanning Calorimetry and in-situ Transmission Electron Microscopy annealing is used to study the onset of crystallization of the amorphous coating. The in-situ TEM analyses reveal the formation of first crystallites after annealing at 400 °C for 30 min. Upon a temperature increase to 500–600 °C, the crystallites develop into Fe-rich nanocrystals with ~ 40 nm grain size. The nanocrystals are dispersed in the remaining amorphous Fe-W matrix, which results in the formation of a mixed nanocrystalline-amorphous structure. The observed crystallization can be held responsible for the increase in the hardness obtained upon annealing of Fe-24at.%W coatings. In fact, the hardness of the as-deposited material increases from 11 to 13 GPa after annealing at 400 °C, and it reaches the maximum value of 16.5 GPa after annealing at 600 °C.

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