Saint-Maurice-de-Gourdans, France
Saint-Maurice-de-Gourdans, France

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Raphael C.,Normandie University | Raphael C.,Laboratoire Polymeres | Raphael C.,CNRS Polymers, Biopolymer and Surfaces Laboratory | Nadege F.,Normandie University | And 10 more authors.
Advanced Materials Research | Year: 2013

Nanocomposites based on bacterial semi-crystalline polyhydroxyalkanoates, poly(3- hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) or poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P(3HB-co-4HB)), and organo-modified montmorillonite nanoclay are prepared by melt processing. All nanocomposites are characterized by X-Ray Diffraction (XRD) and Transmission Electronic Microscopy (TEM) and exhibit a mainly intercalated structure. Concerning water transport properties, a decrease of barrier properties for PHBV/nanoclay films is measured due to the affinity of nanoclay to water; whereas for P(3HB-co-4HB)/nanoclay nanocomposites, a decrease of the water permeability is observed relative to the tortuosity effect. Eventually, as a function of nanoclay content, a competition is evidenced between the tortuosity effect and the water sorption induced by nanoclay. © (2013) Trans Tech Publications, Switzerland.

Soto Puente J.A.,Normandie University | Soto Puente J.A.,Laboratoire Polymeres | Soto Puente J.A.,CNRS Polymers, Biopolymer and Surfaces Laboratory | Soto Puente J.A.,INSA Rouen | And 8 more authors.
Journal of Membrane Science | Year: 2015

A new functional membrane based on poly(ethylene-co-vinyl acetate) (EVA) and poly(ethylene-co-vinyl alcohol) (EVOH) was obtained by hydrolysis reaction on both surfaces of an EVA film, and as a result a three-layered structure (EVOH/EVA/EVOH) was formed. The chemical modification of the film and the thickness of hydrolyzed layer were controlled by FTIR and fluorescent microscopy measurements, respectively. The influence of the hydrolysis time (th) on the thermal properties and membrane microstructure, studied by thermal analysis and X-ray diffraction measurements, indicated the evolution from the amorphous state to the semicrystalline one. The impact of the microstructure modification on the water transport properties was evaluated by permeability and sorption measurements. The plasticization effect of the three-layered membrane was found to be 2 times higher than that in the case of the completely hydrolyzed membrane (th>72h). Such behavior was related to the amorphous/crystalline state of EVOH in the membrane. The results of water sorption measurements indicated that the water desorption is delayed at the highest temperatures in the case of the three-layered membranes. A strong correlation between the water properties of the hydrolyzed EVA membranes and the EVOH structure was observed. In addition, to providing details on structural characteristics of the three-layered multifunctional membrane with tunable water barrier properties, some possible applications where controlled moisture is necessary (such as food packaging or proton exchange fuel cell membrane) were discussed. © 2015 Elsevier B.V..

Cretois R.,Normandie University | Cretois R.,Laboratoire Polymeres | Cretois R.,CNRS Polymers, Biopolymer and Surfaces Laboratory | Delbreilh L.,Normandie University | And 11 more authors.
European Polymer Journal | Year: 2013

Two types of bacterial semi-crystalline copolyesters, poly(3- hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and poly(3-hydroxybutyrate-co-4- hydroxybutyrate) (P3HB4HB) are studied neat or with 8 wt% of Cloisite® C30B (C30B) organoclays. Wide Angle X-ray Diffraction (WAXD) and Differential Scanning Calorimetry (DSC) reveal that the nanoclays are partially intercalated, exfoliated and agglomerated. With selected sample preparation, the crystalline phase is unaffected by the C30B presence. Broadband Dielectric Spectroscopy (BDS) measurements showed no influence of the nanoclays on the secondary local relaxations modes of both polymers and on the segmental relaxation of P3HB4HB. Nevertheless, a strong modification of the α relaxation of PHBV has been observed after incorporation of C30B. A strong decrease of the fragility index and of the glass transition temperature revealed an increase of the molecular mobility in the amorphous fraction influenced by the nanoclays. © 2013 Elsevier Ltd. All rights reserved.

Puente J.A.S.,Normandie University | Puente J.A.S.,INSA Rouen | Puente J.A.S.,Laboratoire Polymeres | Puente J.A.S.,CNRS Polymers, Biopolymer and Surfaces Laboratory | And 11 more authors.
Polymer (United Kingdom) | Year: 2015

The segmental dynamics of amorphous poly(ethylene-vinyl acetate) copolymers (from PVAc to EVA50) were studied. In that sample set with similar backbone stiffness and different amount of dipoles, the dynamic glass transition was investigated by Modulated Temperature Differential Scanning Calorimetry and Broadband Dielectric Spectroscopy measurements. A decrease of the cooperativity length scale was obtained with the vinyl acetate (VAc) content decreasing. On the other hand, there was no modification of the temperature dependence of the relaxation time. Thus, the fragility value is quite constant whatever the VAc content. These results show that fragility and cooperativity have two different origins. An extrapolation to nonconstrained polyethylene amorphous phase was proposed and new glass transition temperature and fragility values were determined. © 2015 Elsevier Ltd.

Ratieuville V.,Normandie University | Ratieuville V.,Laboratoire Polymeres | Ratieuville V.,CNRS Polymers, Biopolymer and Surfaces Laboratory | Fatyeyeva K.,Normandie University | And 10 more authors.
Advanced Materials Research | Year: 2013

New porous polyimide films were elaborated by vapor induced phase separation process. The influence of different parameters such as the nature of the solvent, the molecular weight of the porous agent, and relative humidity on the structure of the film was investigated. It was shown that the porous film prepared from NMP presents the most original morphology with micro- and nanopores. Moreover, such structure is only obtained when the porous agent used has a high molecular weight. The synthesized porous film was swelled in protic ionic liquid for fuel cell application. The performed conductivity measurements as a function of temperature have shown that the conductivity of the impregnated polyimide film increases when the temperature rises up to 150 °C following Arrhenius behavior. © (2013) Trans Tech Publications, Switzerland.

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