Occupied and Accessible Volumes in Glassy Polymers and Their Relationship with Gas Permeation Parameters

Ronova, I. A.; Rozhkov, E. M.; Alentiev, A. Yu.; Yampolskii, Yurii P.

doi:10.1002/mats.200350002

Cited by 41 publications

(34 citation statements)

References 35 publications

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“…The following values of matrix density were obtained: 0.854 ± 0.005 g/cm 3 (PE) and 1.289 ± 0.012 g/cm 3 (PI). These values are slightly lower than the experi mental magnitudes for polyethylene [41,42] and poly imides [43,44], because the constructed samples have purely amorphous structures. Note that the obtained density for polyethylene agrees well with the experimen tal value of the amorphous domains of the polyethylene matrix calculated by the extrapolation of a specific vol ume determined at high temperatures (243-350 K) [45] to the normal conditions.…”

Section: Resultscontrasting

confidence: 50%

Interface structure in polymer nanocomposites containing surface-modified nanoparticles: Atomistic simulation

et al. 2012

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The structural properties of an organic-inorganic nanocomposite composed of polyimide and surface modified silicon oxide nanoparticles were studied by atomistic molecular dynamics. Alkylsilanyl molecules were used as a surface modifier. For the sake of simplicity, the model of the material was built as a layer of a polymer matrix inserted between two solid surfaces. The surface density and chain length of modi fier molecules were the main computation parameters. The results of computations show that the properties of the interface between a matrix and inorganic filler can be changed by varying the molecular weight and the surface density of the modifier.

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Section: Resultscontrasting

confidence: 50%

Interface structure in polymer nanocomposites containing surface-modified nanoparticles: Atomistic simulation

et al. 2012

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“…The conditions (15)(16)(17) are checked now only for the points hitting the area Q 0 ijk , and so the speed of volume corrections computation increases signi¯cantly. As before, volume corrections are calculated by formula (13).…”

Section: A Combined Algorithm For Volume Corrections Calculationsmentioning

confidence: 99%

Methods for the calculation of occupied volumes in glassy polymers: The lattice integration and the monte carlo methods

2003

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A new model for characterizing the free volume of a glassy polymer { gas systems is proposed. An improved method for the calculation of occupied volume per monomer unit was developed within the limits of this model. The model assumptions, error estimates and algorithm e¯ciencies are described. Using the example of polyvinyltrimethylsilane, it is shown that linear dependences of logarithms of the di¬usion and the permeability coe¯cients on speci c accessible volume for inert gases exist.

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“…Decreases in the FFV have been modeled and correlated to decreases in gas permeability. [75,76,77,78] This phenomena has been observed with poly(trimethylsilylpropyne) (PTMSP), another high free volume polymer. [79] The fractional free volume in the polymer film can be indirectly monitored by measuring the bulk density of the film.…”

Section: Resultsmentioning

confidence: 91%

Advanced proton-exchange materials for energy efficient fuel cells.

Fujimoto¹,

Grest²,

Hickner³

et al. 2005

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The Advanced Proton-Exchange Materials for Energy Efficient Fuel Cells Laboratory Directed Research and Development (LDRD) project began in October 2002 and ended in September 2005. This LDRD was funded by the Energy Efficiency and Renewable Energy strategic business unit. The purpose of this LDRD was to initiate the fundamental research necessary for the development of a novel proton-exchange membranes (PEM) to overcome the material and performance limitations of the "state of the art" Nafion that is used in both hydrogen and methanol fuel cells. An atomistic modeling effort was added to this LDRD in order to establish a frame work between predicted morphology and observed PEM morphology in order to relate it to fuel cell performance. Significant progress was made in the area of PEM material design, development, and demonstration during this LDRD.A fundamental understanding involving the role of the structure of the PEM material as a function of sulfonic acid content, polymer topology, chemical composition, molecular weight, and electrode electrolyte ink development was demonstrated during this LDRD. PEM materials based upon random and block polyimides, polybenzimidazoles, and polyphenylenes were created and evaluated for improvements in proton conductivity, reduced swelling, reduced O 2 and H 2 permeability, and increased thermal stability. Results from this work reveal that the family of polyphenylenes potentially solves several technical challenges associated with obtaining a high temperature PEM membrane. Fuel cell relevant properties such as high proton conductivity (>120 mS/cm), good thermal stability, and mechanical robustness were demonstrated during this LDRD. This report summarizes the technical accomplishments and results of this LDRD. 3 AcknowledgementsThis LDRD project benefited from the technical assistance of Los Alamos National Labs Fuel Cell group (Bryan Pivovar) for insight on how to construct a membrane electrode assembly (MEA) and the testing of a polymer electrolyte membrane (PEM) within a hydrogen and methanol fuel cells for initial material performance. The collection and evaluation of some of our hydrogen fuel cell data was performed by Paul Daily. We would also like to thank Brian Einsla and Juan Yang in the Chemistry Department at Virginia Tech for performing the GPC analysis for the determination of the molecular weight. Finally, a special thank you is in order for the champions of this project James Gee and Larry Bustard. Snapshots of the evaporation process for system II (upper panels) and IV (lower panels), listed in Table I, at 25%, 50%, and 94% evaporated solvent. Solvent monomers are colored red, and type 2 and type 3 polymer monomers are colored green and black, respectively. Note that the ordering appears as a result of solvent evaporation. The direction of evaporation is z and is perpendicular to both x and y.. Morphology of the resulting films in the surface plane for mono and polydispersed chain length multiblock copolymers with varying relative stiffnesses. Six cas...

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Occupied and Accessible Volumes in Glassy Polymers and Their Relationship with Gas Permeation Parameters

Cited by 41 publications

References 35 publications

Interface structure in polymer nanocomposites containing surface-modified nanoparticles: Atomistic simulation

Interface structure in polymer nanocomposites containing surface-modified nanoparticles: Atomistic simulation

Methods for the calculation of occupied volumes in glassy polymers: The lattice integration and the monte carlo methods

Advanced proton-exchange materials for energy efficient fuel cells.

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