Novel Method to Assess the Molecular Weights of Fluoropolymers by Radical Copolymerization of Vinylidene Fluoride with Various Fluorinated Comonomers Initiated by a Persistent Radical

2013 ◽  
Vol 46 (8) ◽  
pp. 3092-3106 ◽  
Author(s):  
Yogesh Patil ◽  
Ali Alaaeddine ◽  
Taizo Ono ◽  
Bruno Ameduri
Keyword(s):  
Vinylidene Fluoride ◽  
Radical Copolymerization ◽  
Molecular Weights ◽  
Novel Method

Radical Copolymerization of α,β-Difluoroacrylic Acid with Vinylidene Fluoride.

2010 ◽  
Vol 43 (11) ◽  
pp. 4879-4888 ◽  
Author(s):  
Frédéric Boschet ◽  
Jean-Marc Cracowski ◽  
Véronique Montembault ◽  
Bruno Ameduri
Keyword(s):  
Vinylidene Fluoride ◽  
Radical Copolymerization

Synthesis and characterization of amphiphilic graft copolymers with hydrophobic poly(α-methylstyrene) backbone and hydrophilic poly(n-vinylpyrrolidone) side chains

e-Polymers ◽  
2012 ◽  
Vol 12 (1) ◽  
Author(s):  
Fatima Zohra Sebba ◽  
Seghier Ould Kada ◽  
Mohamed Benaicha ◽  
Nerjesse Nemiche
Keyword(s):  
Graft Copolymer ◽  
Graft Copolymers ◽  
Radical Copolymerization ◽  
Side Chains ◽  
Free Radical Copolymerization ◽  
Good Efficiency ◽  
Molecular Weights ◽  
Grafting Reaction ◽  
Viscosity Variation ◽  
End Capping

AbstractIn this study, 2-oxopropylmethacrylate-terminated poly(N-vinyl-2- pyrrolidone) is produced by cationic polymerization using HClO4 as an initiator. Termination (end capping) step is accomplished using 2- hydroxypropylmethacrylate (2HPMA) and the polymer product has different chain lengths of molecular weight averages ranging from 672 to 3049 g/mol. The study also synthesised amphipathic graft copolymers having hydrophobic poly(α- methylstyrene) as a backbone chain and hydrophilic poly(N-vinyl-2-pyrrolidone) (PVP) as side chains of various lengths. The copolymer synthesis was accomplished by free radical copolymerization of ω-oxopropylmethacrylate PVP in the presence of α-methyl styrene initiated with benzoyl peroxide. Measurements of the dynamic viscosity of the polymer solution (20% weight of macromonomers in ethanol) show that the viscosity is proportional to the average molecular weights M̅n . However, a reverse behaviour of the viscosity variation with regard to M̅n is observed for graft copolymer samples. The viscosity variation with respect to the graft copolymer mass must be due to steric effects, which are strongly pronounced in grafted copolymer chains. Appearance of the number of side chains attached to poly(α-methylstyrene) backbone reveals that the grafting reaction has occurred with good efficiency.

Convection as one of the limiting factors of human respiration during normoxic exercise

1997 ◽  
Vol 272 (6) ◽  
pp. R1874-R1879 ◽  
Author(s):  
H. Heller ◽  
K. D. Schuster
Keyword(s):  
Isotopic Analysis ◽  
Cycle Ergometer ◽  
Limiting Factors ◽  
Fractionation Factor ◽  
Molecular Weights ◽  
Relative Contribution ◽  
O2 Transport ◽  
Human Respiration ◽  
Novel Method ◽  
Factor Alpha

Each of the pathways within respiration has been suspected of limiting maximal performance, suggesting that O2 transport may be affected by each single pathway. The use of the stable, isotopic O2 molecules 16O2 and 16O18O is presented as a novel method for assessing respiration. Because of their different molecular weights, 16O2 diffuses 3% more rapidly than 16O18O, whereas 16O2 is convectively transported as rapidly as 16O18O. This can be quantified by using the overall fractionation factor alpha O. The more diffusion becomes limiting, the more 16O2 is transported in preference to 16O18O and alpha O is increased to 1.03. By contrast, the more respiration is limited by convection, the closer alpha O comes to 1.0 during the entire O2 transport. Six untrained subjects underwent normoxic exercise on a cycle ergometer. Isotopic analysis was performed at rest and during exercise loads of 50, 100, 150, 200, and 250 W using respiratory mass spectrometry. With increasing workload, a decrease in alpha O from 1.0072 at rest to 1.0033 at 250 W was determined in all subjects. On the basis of a serial resistance model of respiration, we concluded that, in our subjects, O2 transport was increasingly affected by convection but decreasingly limited by diffusion. The relative contribution of convection to the entire resistance to O2 flow ranged from > or = 44.6% at rest to > or = 74.6% at the most strenuous level of exercise, whereas the diffusive pathways decreasingly contributed to resistance to O2 flow by < or = 24% at rest and < or = 11% at 250 W.

scholarly journals Effect of Graphene oxide or Functionalized Graphene Oxide on the Copolymerization Kinetics of Styrene/n-butyl Methacrylate

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 999 ◽  
Author(s):  
Ioannis Tsagkalias ◽  
Afrodite Vlachou ◽  
George Verros ◽  
Dimitris Achilias
Keyword(s):  
Graphene Oxide ◽  
Radical Copolymerization ◽  
Butyl Methacrylate ◽  
Side Reactions ◽  
Hydroxyl Groups ◽  
Functionalized Graphene ◽  
Functionalized Graphene Oxide ◽  
Molecular Weights ◽  
Diffusion Controlled ◽  
Kinetic Rate Constants

Nanocomposite materials based on copolymers of styrene and n-butyl methacrylate with either graphene oxide (GO) or functionalized graphene oxide (F-GO) were synthesized using the in-situ bulk radical copolymerization technique. Reaction kinetics was studied both experimentally and theoretically using a detailed kinetic model also taking into account the effect of diffusion-controlled phenomena on the reaction kinetic rate constants. It was found that the presence of GO results in lower polymerization rates accompanied by the synthesis of copolymers having higher average molecular weights. In contrast, the presence of F-GO did not seem to significantly alter the conversion vs time curves, whereas it results in slightly lower average molecular weights. The first observation was attributed to side reactions of the initiator primary radicals with the hydroxyl groups on the surface of GO, resulting in lower initiator efficiency, whereas the second to grafted structures formed from copolymer macromolecules on the F-GO surface. The copolymerization model predictions including MWD data were found to be in satisfactory agreement with the experimental data. At least four adjustable parameters were employed and their best-fit values were provided.

Radical copolymerization of vinylidene fluoride with 1-bromo-2,2-difluoroethylene

2010 ◽  
Vol 48 (18) ◽  
pp. 3964-3976 ◽  
Author(s):  
G. K. Kostov ◽  
L. Sauguet ◽  
B. Ameduri ◽  
H. Kaspar ◽  
T. Zipplies ◽  
...  
Keyword(s):  
Vinylidene Fluoride ◽  
Radical Copolymerization

The Synthesis and Crystallization of Poly(vinylidene fluoride) in Supercritical CO2

e-Polymers ◽  
2006 ◽  
Vol 6 (1) ◽  
Author(s):  
Zhendong Shi ◽  
Zhen Zheng ◽  
Xiaoli Su ◽  
Xinling Wang
Keyword(s):  
Vinylidene Fluoride ◽  
Degree Of Crystallinity ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Molecular Weights ◽  
Good Solubility ◽  
Poly Vinylidene Fluoride ◽  
Ft Ir ◽  
Application Fields ◽  
Crystallization Mode

AbstractA series of poly(vinylidene fluoride)s (PVDFs) is synthesized in supercritical carbon dioxide (sc-CO2). The influences of polymerization pressure, molecular weight distribution and H-H defect concentration on the crystallization of PVDF have been studied in combination with differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXRD) and Fourier transform infrared spectroscopy (FT-IR) measurements. The result shows that the morphology, molecular weights, polydispersity and head-to-head (H-H) defect concentrations of the PVDFs are affected by the reaction pressure and good solubility generated from sc-CO2. Especially, the sc-CO2 polymerization has greatly improved the crystallization mode of the obtained PVDFs such as the complete degree of crystallinity, crystallinity and the crystal phase. This will create more comprehensive application fields for PVDF.

scholarly journals Cobalt-Mediated Radical Copolymerization of Vinylidene Fluoride and 2,3,3,3-Trifluoroprop-1-ene

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2676
Author(s):  
Panagiotis G. Falireas ◽  
Bruno Ameduri
Keyword(s):  
Diblock Copolymers ◽  
Molar Mass ◽  
Vinylidene Fluoride ◽  
Monomer Conversion ◽  
Radical Copolymerization ◽  
Reactivity Ratios ◽  
Mean Square ◽  
Kinetics Studies ◽  
Lower Reactivity ◽  
Fitting Model

New copolymers based on vinylidene fluoride (VDF) and 2,3,3,3-tetrafluoroprop-1-ene (1234yf) were synthesized by organometallic-mediated radical copolymerization (OMRcP) using the combination of bis(tert-butylcyclohexyl) peroxydicarbonate initiator and bis(acetylacetonato)cobalt(II), (Co(acac)2) as a controlling agent. Kinetics studies of the copolymerization of the fluoroalkenes copolymers were monitored by GPC and 19F NMR with molar masses up to 12,200 g/mol and dispersities (Đ) ranging from 1.33 to 1.47. Such an OMRcP behaves as a controlled copolymerization, evidenced by the molar mass of the resulting copolymer-monomer conversion linear relationship. The reactivity ratios, ri, of both comonomers were determined by using the Fineman-Ross and Kelen-Tüdos fitting model leading to rVDF = 0.384 ± 0.013 and r1234yf = 2.147 ± 0.129 at 60 °C, showing that a lower reactivity of VDF integrated in the copolymer to a greater extent leads to the production of gradient or pseudo-diblock copolymers. In addition, the Q (0.03) and e (0.06 and 0.94) parameters were assessed, as well as the dyad statistic distributions and mean square sequence lengths of PVDF and P1234yf.

Kinetics of radical copolymerization of vinylidene fluoride with tert-butyl 2-trifluoromethyl acrylate: a suitable pair for the synthesis of alternating fluorinated copolymers

2018 ◽  
Vol 9 (27) ◽  
pp. 3754-3761 ◽  
Author(s):  
Panagiotis G. Falireas ◽  
Mohammad Wehbi ◽  
Ali Alaaeddine ◽  
Bruno Améduri
Keyword(s):  
Vinylidene Fluoride ◽  
Radical Copolymerization ◽  
Tert Butyl ◽  
Fluorinated Copolymers ◽  
Kinetics Of ◽  
Copolymerization Kinetics

A study of the copolymerization kinetics of vinylidene fluoride with tert-butyl 2-trifluoromethyl acrylate: a suitable pair for the synthesis of alternating fluorinated copolymers.

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