FTIR study on the nature of water sorbed in polypropylene (PP)/ethylene alcohol vinyl (EVOH) films

Lasagabáster, Aurora; Abad, M. J.; Barral, L.; Ares, Ana

doi:10.1016/j.eurpolymj.2006.03.029

Cited by 82 publications

(72 citation statements)

References 25 publications

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“…Such behavior was already been discussed in the literature 1,12 . Nevertheless, the difference of the spectra of the solids NHT, HT560 and HT760 minus HT960 (Figure 4) provides evidence of a small signal centered at 1622 cm -1 that agrees well with the deformation vibration of physically adsorbed molecular water [37][38][39][40] ; whose intensity decreases with the increasing temperature of the hydrothermal treatment. Similarly, the bands at 3785 cm -1 and 3700-3642 cm -1 , reasonably agree with the asymmetric and symmetric stretching vibrations of physisorbed water molecules 32,33 .…”

Section: Temperature-programmed Desorption Of Ammonia (Tpd-nh 3 )mentioning

confidence: 69%

FTIR study of the relation, between extra-framework aluminum species and the adsorbed molecular water, and its effect on the acidity in ZSM-5 steamed zeolite

Isernia

2013

Mat. Res.

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The infrared spectroscopy study of zeolite samples, obtained by steam treatment at 560-960 °C of the ZSM-5 catalyst (framework Si/Al ratio of 13), suggests an association between adsorbed molecular water and extra-framework aluminum hydroxyls generated after treatment. Moreover, infrared spectroscopy of adsorbed pyridine shows the reduction of the densities of Brönsted and Lewis sites, when treatment temperature rises, with contradicts the frequently accepted mechanism of the transformation of two bridged Si-OH-Al groups for each Lewis site generated. The gradual conversion of the octahedral extra-framework aluminum (Lewis-associated) in polymeric species with low acidity is the most probable cause of this behavior. On the other hand, the apparent decline of the acid Brönsted strength, with the increase in the temperature of the hydrothermal treatment, has two possible causes: a) the decreasing accessibility, of the pyridine molecular probe to bridged Si-OH-Al groups with the strongest Brönsted acidity, inside the channels, and b) the gradual transformation of these groups into extra framework species of weak acidity.

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Section: Temperature-programmed Desorption Of Ammonia (Tpd-nh 3 )mentioning

confidence: 69%

FTIR study of the relation, between extra-framework aluminum species and the adsorbed molecular water, and its effect on the acidity in ZSM-5 steamed zeolite

Isernia

2013

Mat. Res.

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“…The OH stretch of water presents an extremely broad band between 3,000 and 3,700 cm À 1 , which is usually described by the four state model 27 in terms of the strength of hydrogen bonding. The intra-molecular OH stretch is highly dependent on the hydrogen-bond coordination of the proton 28 .…”

Section: Gnbs On Diamondmentioning

confidence: 99%

A hydrothermal anvil made of graphene nanobubbles on diamond

et al. 2013

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The hardness and virtual incompressibility of diamond allow it to be used in high-pressure anvil cell. Here we report a new way to generate static pressure by encapsulating singlecrystal diamond with graphene membrane, the latter is well known for its superior nanoindentation strength and in-plane rigidity. Heating the diamond-graphene interface to the reconstruction temperature of diamond (B1,275 K) produces a high density of graphene nanobubbles that can trap water. At high temperature, chemical bonding between graphene and diamond is robust enough to allow the hybrid interface to act as a hydrothermal anvil cell due to the impermeability of graphene. Superheated water trapped within the pressurized graphene nanobubbles is observed to etch the diamond surface to produce a high density of square-shaped voids. The molecular structure of superheated water trapped in the bubble is probed using vibrational spectroscopy and dynamic changes in the hydrogen-bonding environment are observed.

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“…In addition, owing to the free-radical nature of the EVA copolymerization, the resulting EVOH copolymers posses a certain degree of short chain branching, which, according to Vanderhart et al [4] are rejected from the crystalline region. EVOH copolymers are widely employed in food packaging, biomedical and pharmaceutical industries because of their excellent barrier properties to gases, hydrocarbons and organic solvents [3,5]. Such properties are caused by strong hydrogen bond interactions, both inter and intra-molecular, which reduce the free volume of the polymer chains [6].…”

Section: Introductionmentioning

confidence: 99%

Influence of processing on the ethylene-vinyl alcohol (EVOH) properties: Application of the successive self-nucleation and annealing (SSA) technique

Urquiza¹,

Santana

Gámez‐Pérez³

et al. 2010

Express Polym. Lett.

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Abstract. Films of EVOH copolymers, processed three times by twin-screw extrusion were prepared using a cast-film line. The variation on the melt flow rate (MFR) and rheological behaviour of the films were determined, as well as the thermal properties assessed by differential scanning calorimetry (DSC) and dynamic-mechanical thermal analysis (DMTA). As the results showed that the reprocessing induced an increase in the viscosity and orientation of the films, it was suggested that structural modifications from chain-extension or cross-linking reactions promoted by hydroxyl and residual acetoxyl groups, could be occurring. The successive self-nucleation and annealing (SSA) technique was applied, evidencing the structural modifications on the EVOH copolymer.

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FTIR study on the nature of water sorbed in polypropylene (PP)/ethylene alcohol vinyl (EVOH) films

Cited by 82 publications

References 25 publications

FTIR study of the relation, between extra-framework aluminum species and the adsorbed molecular water, and its effect on the acidity in ZSM-5 steamed zeolite

FTIR study of the relation, between extra-framework aluminum species and the adsorbed molecular water, and its effect on the acidity in ZSM-5 steamed zeolite

A hydrothermal anvil made of graphene nanobubbles on diamond

Influence of processing on the ethylene-vinyl alcohol (EVOH) properties: Application of the successive self-nucleation and annealing (SSA) technique

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