A pulsed field gradient NMR study of diffusion in semicrystalline polymers: self-diffusion of alkanes in polyethylenes

Fleischer, G.

doi:10.1007/bf01490024

Cited by 38 publications

(16 citation statements)

References 35 publications

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“…Because the rather low amount of liquid found in the semi-crystalline PE, the signal-to-noise ratio was rather poor for the part of the experimental attenuation curve representing this diffusivity. The diffusion coefficient representing diffusion of liquid in semi-crystalline PE (D sc ) varied randomly in the range 1-4 × 10 −11 m 2 s −1 , a value which corresponds to similar results found in the literature (23,24).…”

Section: Figmentioning

confidence: 91%

“…Since a typical value for diffusion of liquid dissolved in semi-crystalline PE is around 1-5 × 10 −11 m 2 s −1 (23,24), even at t d ≈ 200 ms, the diffusion length in this domain will be approximately 2-3 µm, and there should be no significant amount of exchange between the two domains. In addition, as shown below, it was found that the estimated fraction of liquid found in semi-crystalline PE did not vary significantly with the observation time, which should be the case if there was significant exchange taking place.…”

Section: Diffusion In the Polyethylene Systemsmentioning

confidence: 99%

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A PFG-NMR Study of Restricted Diffusion in Heterogeneous Polymer Particles

Seland¹,

Ottaviani²,

Hafskjold³

2001

Journal of Colloid and Interface Science

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Section: Figmentioning

confidence: 91%

Section: Diffusion In the Polyethylene Systemsmentioning

confidence: 99%

A PFG-NMR Study of Restricted Diffusion in Heterogeneous Polymer Particles

Seland¹,

Ottaviani²,

Hafskjold³

2001

Journal of Colloid and Interface Science

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“…The free volume of polyethylene was extrapolated from the measurements of Doolittle [22] with the assumption of/g = 0.025 at T--36 ~ (see also [23]). Figure 1.…”

Section: (7)mentioning

confidence: 99%

The chain length dependence of self-diffusion in melts of polyethylene and polystyrene

Fleischer

1987

Colloid & Polymer Sci

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Abstract:The self-diffusion coefficients in melt s of polyethylene fractions and polystyrene standards were measured by the NMR pulsed field gradient technique and compared with those measured by other techniques. The data agree very wellifone takes into account the molar mass distribution of the samples and the free volume of the matrix. For molar masses much higher than the critical molar mass Mc, reptation is confirmed, D M-2 holds. Below Me = Mff2 the self-diffusion coefficients corrected for constant free volume show approximately the dependence D -M-1 confirming Rouse-like diffusion. This result was also obtained by investigating the self-diffusion of the molecules with different molar masses of a polyethylene fraction with a rather broad molar mass distribution around Me and Me, i. e. diffusion in a constant matrix. In the molar mass region between Mc and about 3. Mc the observed molar mass dependence of self-diffusion can be explained by tube formation. The constraint release model of Graessley seems to slightly overestimate the self-diffusion coefficients.

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“…Diffusion of molecules is thought to be mainly limited to the amorphous regions (zones B and D) while the crystalline domain (zone A) should represent an essentially excluded volume (Klute 1959;Lasoski and Cobbs 1959;Jeschke and Stuart 1961;Fleischer 1984). Thus, similar to a technical barrier membrane (Cussler et al 1988), cuticular wax consists of a permeable matrix, the amorphous phase, and impermeable flakes embedded within this matrix, the crystalline phase (Riederer and Schreiber 1995).…”

Section: Discussionmentioning

confidence: 96%

Transport properties of cuticular waxes of Fagus sylvatica L. and Picea abies (L.) Karst.: Estimation of size selectivity and tortuosity from diffusion coefficients of aliphatic molecules

Schreiber

Kirsch

Riederer

1996

Planta

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Abstract. Diffusion coefficients for thirteen lipophilic organic compounds in reconstituted waxes of Fagus sylvatiea L. and Picea abies (L.) Karst. were measured to characterise the transport properties of the cuticular waxes that form the transport-limiting barrier of plant cuticles. Desorption kinetics (relative amounts desorbed versus time) were asymptotic, but could be linearized up to 50% desorption by plotting relative amounts desorbed versus the square root of time. Diffusion coefficients calculated from the slopes of the linear regressions ranged from 10-22 to 10-17 m2.s -1 and decreased with increasing molecular size. This size dependency of diffusion coefficients was analysed, assuming an exponential dependence of the diffusion coefficients on molar volumes, which allowed cuticular transport properties to be related to the physical structure of the wax. Furthermore, the fact that the barrier properties of Fagus wax are less pronounced than those of Picea is interpreted as an ecological adaptation of the respective tree species to their habitats at the level of their cuticular transport barriers.

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A pulsed field gradient NMR study of diffusion in semicrystalline polymers: self-diffusion of alkanes in polyethylenes

Cited by 38 publications

References 35 publications

A PFG-NMR Study of Restricted Diffusion in Heterogeneous Polymer Particles

A PFG-NMR Study of Restricted Diffusion in Heterogeneous Polymer Particles

The chain length dependence of self-diffusion in melts of polyethylene and polystyrene

Transport properties of cuticular waxes of Fagus sylvatica L. and Picea abies (L.) Karst.: Estimation of size selectivity and tortuosity from diffusion coefficients of aliphatic molecules

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