Sorption and transport of water in nylon‐6 films

Hernández, Rubén J.; Gavara, Rafael

doi:10.1002/polb.1994.090321407

Cited by 90 publications

(61 citation statements)

References 25 publications

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“…7,16,19,24 Only one particular study reported a maximum for the diffusion coefficient at an RH of 50% at 23°C. 3 Moreover, the magnitude of the obtained diffusion coefficient is in agreement with values reported in the literature (1 × 10 −14 to 1 × 10 −13 m 2 s −1 at 25°C 8 ). In contrast with previous studies on nylon-6.6, a highly nonlinear relation between the moisture content and the diffusion coefficient is observed.…”

Section: ■ Resultssupporting

confidence: 81%

“…In the literature moisture content values are reported in the range from 4% 17 up to 10%. 3,7,16 The moisture content increases disproportional above relative humidities of 65% with respect to the lower humidities. Despite the differences in raw material (e.g., molecular weight) and processing conditions (influences of crystallinity 30 ), the shape of the obtained sorption isotherm is similar to the ones in literature.…”

Section: ■ Materialsmentioning

confidence: 99%

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Quantitative Water Uptake Study in Thin Nylon-6 Films with NMR Imaging

Reuvers

Huinink

Fischer³

et al. 2012

Macromolecules

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Nylon-6 is widely used as an engineering plastic. Compared to other synthetic polymers, nylon-6 absorps significant amounts of water. Although the typical sorbed amounts and diffusivity of water are well-known, less is known about the relation between the diffusivity and the water content. Attempts have been made in the past to obtain such relationship from moisture content profiles as measured with NMR imaging. However, these studies were mainly performed at high temperatures and without a proper calibration of the signal. In particular, at room temperature, far below the T g of dry nylon, plasticizing effects of water will result in a strong contribution of the polymer signal. Therefore, we have studied water uptake in 200 μm nylon-6 films in this temperature range near room temperature with NMR imaging. By calibrating the NMR signal with vapor sorption data, we were able to obtain moisture content profiles. A strongly nonlinear relation between the NMR signal and the moisture was observed at room temperature, which proves that contribution of the polymer to the NMR signal can neither be neglected nor assumed to be constant in time. Furthermore, glass transition temperature measurements combined with the water distribution provide plasticization profiles during water uptake. On the basis of the moisture content profiles, the moisture content dependency of the diffusion coefficient for water uptake is deduced through a Matano−Boltzmann analysis. This relation appeared to be highly nonlinear at room temperature. The self-diffusion coefficient was calculated through combination of the sorption-isotherm and the diffusion coefficient. Exposure of a nylon film to heavy water showed that water affects only a small fraction of the amorphous nylon phase. Water transport most likely occurs in this fraction of the amorphous phase. It is concluded that the heterogeneity of the amorphous phase is an important issue for a profound understanding of water transport in nylon-6 films. ■ INTRODUCTIONPolyamides, also known as nylons, are widely used as engineering plastic and textile fiber mainly due to their excellent properties. In particular, the mechanical properties are attractive for many applications and remain unaffected in a wide range of temperatures. Nylon is also easy to process, for example by extrusion molding, which is reflected in the large variety of geometries encountered in every day life.The chemical structure of nylons consists of amide groups separated by a number of methylene units. Therefore, a variety of polyamides exist, consisting of either one single α,ω aminoacid monomer like nylon-6 (PA6) and nylon-12 or two monomers, a dicarboxylic acid and a diamine like nylon 4.6 or 6.6. The number of successive carbon atoms in the polymer backbone between the amide groups is given by the index and influences material properties such a stiffness, melting point or water absorption.1 The latter feature is especially caused by the hydrophilic character of the amide functionality.Nylons absorb amounts of wat...

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Section: ■ Resultssupporting

confidence: 81%

Section: ■ Materialsmentioning

confidence: 99%

Quantitative Water Uptake Study in Thin Nylon-6 Films with NMR Imaging

Reuvers

Huinink

Fischer³

et al. 2012

Macromolecules

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“…137 These results are in agreement with two modes of sorption identified in water uptake measurements with a Cahns electrobalance. 138 However, NMR T 1q measurements reveal three types of water (Fig. 13).…”

Section: State Of Watermentioning

confidence: 99%

Hydrogen bonding, mobility, and structural transitions in aliphatic polyamides

Murthy

2006

J Polym Sci B Polym Phys

215

197

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Some salient results in nylon research are reviewed to identify the fundamental principles that are applicable to other strongly interacting or hydrogenbonded polymers, including proteins. The effects of hydrogen bonds on stress-, heat-, and solvent-induced changes in macroscopic properties are discussed. These data provide a window into the chain mobility and linkages between the crystalline and amorphous domains, both of which are important for any predictive model. The changes in the characteristics of the amorphous phase with the crystallinity and orientation require that it be modeled with at least two components: a rigid/immobile/ anisotropic component and a soft/ mobile/isotropic component. The deformation and shrinkage behavior of these polymers are discussed in terms of the relative contributions of the amorphous and crystalline domains and of the interactions between them. The premelting crystalline transition is accompanied by the merging of intersheet and intrasheet diffraction peaks in some nylons, as observed by Brill, and not in others even though the underlying mechanism that gives rise to these transitions, the onset of volume-increasing librational motion of the crystalline stems, is the same. Because the effects of the temperature, deformation, and solvent have a common origin associated with mobility, a fictive temperature can be associated with a given solvent activity or stress level. The magnitude of this fictive temperature is the amount by which the glass or Brill transition temperature is reduced in the presence of solvents ($50 8C) or stress or by which the annealing temperature can be reduced in the presence of a solvent (or active stress) to achieve the same structural state as that of a dry (or static) polymer.

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“…In practice, it can be representative of the sorption of water in highly hydrophilic polymers (Hernandez and Gavara, 1994;Hernandez et al, 1992): initially, the water molecules are strongly sorbed in specific sites corresponding to polar groups, then at higher pressures, the clustering process may occur.…”

Section: Bet Modementioning

confidence: 99%

Transport Properdines of Gases in Polymers: Bibliographic Review

Klopffer

Flaconnèche

2001

Oil & Gas Science and Technology - Rev. IFP

253

196

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Résumé -Transport de molécules gazeuses dans les polymères : revue bibliographique -Après quelques rappels concernant les lois classiques des phénomènes de transport, cet article, purement bibliographique, présente les différents modèles théoriques proposés pour décrire le mécanisme de transport d'espèces chimiques dans les polymères par diffusion moléculaire. Il s'appuiera ensuite sur de nombreuses études menées antérieurement, pour montrer que la perméabilité des gaz (ou vapeurs organiques) dépend fortement de la structure du polymère (cristallinité, histoire thermomécanique), de la taille et de la nature du pénétrant ainsi que des conditions de température et de pression.Mots-clés : polymère, gaz, perméabilité, diffusion, solubilité. Abstract -Transport Properties of Gases in

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Sorption and transport of water in nylon‐6 films

Cited by 90 publications

References 25 publications

Quantitative Water Uptake Study in Thin Nylon-6 Films with NMR Imaging

Quantitative Water Uptake Study in Thin Nylon-6 Films with NMR Imaging

Hydrogen bonding, mobility, and structural transitions in aliphatic polyamides

Transport Properdines of Gases in Polymers: Bibliographic Review

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