The origins of fast segmental dynamics in 2 nm thin confined polymer films

Manias, Evangelos; Kuppa, Vikram

doi:10.1140/epje/i2001-10074-x

Cited by 43 publications

(48 citation statements)

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“…Thus, for all the data shown -seal strengths, ATR-FT-IR spectra, ESEM and EDS spectra -the results are consistent only when the interfacial strength increases from weakest between PE and EVA/clay, to weak between PE and clay, to stronger between PE and EVA, in agreement with theoretical and simulation considerations [46,[50][51][52]. Consequently, the origins of the peelable nature of this PE/EVA/clay nanocomposite sealant can be traced to its cohesive failure, mediated by weak interfaces within the nanocomposite, as is schematically illustrated in Fig.…”

Section: Characterization Of Fractured Seal Surfaces and Proposed Mecsupporting

confidence: 78%

Tailored Polyethylene Nanocomposite Sealants: Broad-Range Peelable Heat-Seals Through Designed Filler/Polymer Interfaces

Zhang

Manias

Polizos

et al. 2009

Journal of Adhesion Science and Technology

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The heat sealing behavior of novel polyethylene-based nanocomposite films was investigated, as they relate to flexible packaging of fresh-cut vegetables, processed foods and biomedical devices. Appropriately designed sealant nanocomposites, which include dispersed montmorillonite nanofillers and ethyl vinyl acetate copolymer, produce a hermetic but peelable heat seal across a broad, 30-40 • C, range of heat sealing temperatures, outperforming optimized commercial polyethylene-based sealants that achieve peelable seals in a much narrower heat sealing temperature range, of less than 15 • C. Appropriate nanocomposite design leads to a general easy-open/peelable character of heat seals, which is: (a) independent of sealing conditions and apparatus -ranging from long dwell times at very high sealing pressures to very short heat impulses at very low sealing pressures; (b) markedly independent of the opposite side of the heat seal -for example, when sealed on itself, on unfilled sealant, or on high density polyethylene; and (c) rather insensitive to formulation variations of the sealant -for example, variations of the polyethylene of the ethyl vinyl acetate type and concentration, and of nanofiller loading. Insights from observations of the fracture seal surfaces by infrared spectroscopy and electron microscopy reveal that the underlying mechanism of this behavior is related to a synergistic effect of the ethyl vinyl acetate copolymer and the montmorillonite clay nanofiller, which introduces weak interfaces in the nanocomposite that lead to cohesive failure of the sealant.

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Section: Characterization Of Fractured Seal Surfaces and Proposed Mecsupporting

confidence: 78%

Tailored Polyethylene Nanocomposite Sealants: Broad-Range Peelable Heat-Seals Through Designed Filler/Polymer Interfaces

Zhang

Manias

Polizos

et al. 2009

Journal of Adhesion Science and Technology

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“…[1][2][3] The flame retardant effect of those nanoparticles is attributed to char formation on top of the burning polymer. These fillers act via a condensed phase flame retardation mechanism, which is purely physical in nature.…”

Section: Introductionmentioning

confidence: 99%

Calcium carbonate and ammonium polyphosphate‐based flame retardant composition for polypropylene

Deodhar

Shanmuganathan

Fan

et al. 2010

J of Applied Polymer Sci

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ABSTRACT:The chemical mode of action as a flame retardant of calcium carbonate nanoparticles combined with ammonium polyphosphate in polypropylene was investigated. Reduction in burning rates for 0.5 mm thick samples were observed without appreciable char formation up to 30 wt % loading of additives. Thermogravimetric analysis (TGA) of the mixture of CaCO 3 and ammonium polyphosphate (APP) showed that calcium carbonate nanoparticles react with ammonium polyphosphate before the degradation of the phosphate chains. TGA-FTIR studies of the polymer composite samples and powder mixtures of the additives confirmed the evolution of ammonia and carbon dioxide due to interaction between the additives. X-ray diffraction (XRD) analysis of chars, obtained after burning the films, showed definite diffraction peaks corresponding to that of calcium metaphosphate. The inert gasses produced by the interaction of the additives hindered the advancing flame and, thus, reduces the burning rates, at times even without char formation.

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“…2 Because these systems self-assemble in highly ordered intercalated structures, it is easy to prepare samples with macroscopic quantities of severely confined polymers so that conventional analytical techniques such as solid-state NMR, dielectric spectroscopy, and X-ray and neutron diffraction studies can be successfully applied. [2][3][4][5][6][7][8][9][10][11] Such experimental investigations combined with simulation studies [12][13][14][15][16][17] unveil a striking picture for the physics of polymers in severe confinements between solid surfaces.…”

Section: Introductionmentioning

confidence: 99%

Simulation insights on the structure of nanoscopically confined poly(ethylene oxide)

Kuppa

Menakanit

Krishnamoorti

et al. 2003

J Polym Sci B Polym Phys

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ABSTRACT:We employ atomistic computer modeling to investigate the structure and morphology of poly(ethylene oxide) (PEO) chains confined in 1-nm slit pores defined by montmorillonite silicate layers. Molecular dynamics computer simulations reveal the Li ϩ cations to be located in the immediate vicinity of the silicate surfaces and PEO to adopt highly amorphous conformations in a liquidlike bilayer across the slit pores. Despite the orienting influence of the parallel stacked silicate walls, PEO shows no indication of crystallinity or periodic ordering; in fact, for all temperatures simulated, it is less ordered than the most disordered bulk PEO system. These amorphous PEO film configurations are attributed to the combination of severe spatial confinement and the strong coordination of ether oxygens with the alkali cations present in the interlayer gallery. These conclusions challenge the picture traditionally proposed for intercalated PEO, but they agree with a plethora of experimental observations. Indicatively, the simulation predictions are confirmed by wide-angle neutron scattering and differential scanning calorimetry experiments on PEO/montmorillonite intercalates.

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The origins of fast segmental dynamics in 2 nm thin confined polymer films

Cited by 43 publications

References 0 publications

Tailored Polyethylene Nanocomposite Sealants: Broad-Range Peelable Heat-Seals Through Designed Filler/Polymer Interfaces

Tailored Polyethylene Nanocomposite Sealants: Broad-Range Peelable Heat-Seals Through Designed Filler/Polymer Interfaces

Calcium carbonate and ammonium polyphosphate‐based flame retardant composition for polypropylene

Simulation insights on the structure of nanoscopically confined poly(ethylene oxide)

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