Carbon nanotube conductive networks through the double percolation concept in polymer systems / A. Abbasi in INTERNATIONAL POLYMER PROCESSING, Vol. XXIX, N° 1 (03/2014)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXIX, N° 1 (03/2014) . - p. 13-27 Titre : Carbon nanotube conductive networks through the double percolation concept in polymer systems Type de document : texte imprimé Auteurs : A. Abbasi, Auteur ; A. Derdouri, Auteur ; Pierre J. Carreau, Auteur Année de publication : 2014 Article en page(s) : p. 13-27 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Butylène téréphtalate cyclique Conduction électrique Matériaux hybrides Matières plastiques -- Moulage par micro-injection Nanotubes de carbone à parois multiples Un nanotube de carbone multifeuillet est constitué de plusieurs feuillets de graphènes enroulés les uns autour des autres. Il existe deux modèles pour décrire la structure des nanotubes multifeuillets : - le modèle poupée russe: les plans de graphène sont arrangés en cylindres concentriques ; - le modèle parchemin: un seul feuillet de graphène est enroulé sur lui-même, comme une feuille de papier. Percolation Polybutylène téréphtalate Polypropylène Index. décimale : 668.4 Plastiques, vinyles Résumé : We investigated the electrical conductivity and percolation behavior of binary and ternary nanocomposites based on multiwalled carbon nanotubes (MWCNs) using polypropylene (PP) and a blend of PP with cyclic butylene terephthalate (CBT). The nanocomposites were prepared by diluting a commercial 20 %wtMWCNT PP masterbatch using optimized melt-mixing conditions. The concentration of carbon nanotubes in the diluted PP samples was as low as 0.5 % and as high as 15 % in weight. For the PP/CBT blend CBT concentration was varied up to 40 %wt while the loading of CNT was from 0 to 5 %wt. SEM and TEM techniques were used to examine the quality of the dispersion and the formation of nanotube networks within the polymer matrix. TEM and Raman spectroscopy results showed that for the diluted PP/MWCNT composites the nanotubes are well aligned in samples obtained the microinjection molding process, although the level of alignment is less with crystalline PP than in an amorphous matrix such as polycarbonate (PC). FTIR and XRD results revealed that the orientation of both polymer chains and crystals decreased with the incorporation of nanotubes into PP. The electrical conductivity was also significantly altered by the nanotube alignment in a PP matrix, as was previously observed for PC/MWCNT composites; the conductivity decreased and the percolation threshold rose in highly sheared samples; however, the presence of a crystalline phase improved the conductivity even for high shear conditions through the phenomenon of double percolation threshold. This last concept refers to the requirement that the filler-rich phase be continuous and conductive and not to the existence of two percolation thresholds at two different CNT concentrations. The electrical conductivity of PP/CBT blends was also improved through a double percolation that is the basic requirement for the conductivity of the ternary nanocomposites. Note de contenu : - EXPERIMENTAL : Materials - Nanocomposite preparation and molding - Morphological characterization - Nanotube alignment - Polymer chain and crystal orientation - Rheological measurements - RESULTS : PP nanocomposites - PP/CBT blend nanocomposites DOI : 10.3139/217.2778 En ligne : https://drive.google.com/file/d/1ZJZlKx49qryLnfqR7g8IQdi6ph2N2o-a/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=20571 [article]

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The effect of nanosilicates on the performance of polyethylene terephthalate films prepared by twin-screw extrusion / A. Ghanbari in INTERNATIONAL POLYMER PROCESSING, Vol. 36, N° 4 (2021)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. 36, N° 4 (2021) . - p. 358-366 Titre : The effect of nanosilicates on the performance of polyethylene terephthalate films prepared by twin-screw extrusion Type de document : texte imprimé Auteurs : A. Ghanbari, Auteur ; M.-C. Heuzey, Auteur ; Pierre J. Carreau, Auteur Année de publication : 2021 Article en page(s) : p. 358-366 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Caractérisation Composites -- Propriétés mécaniques Composites -- Propriétés optiques Composites -- Propriétés thermiques Extrudeuse bi-vis Matières plastiques -- Extrusion Montmorillonite Nanoparticules Polyéthylène téréphtalate Silicates Index. décimale : 668.4 Plastiques, vinyles Résumé : Polyethylene terephthalate (PET) films were prepared by cast extrusion using a twin-screw extruder with a severe screw profile. The effect of an organically modified montmorillonite on thermal, mechanical, optical, and barrier properties of the PET films were investigated. Morphological characterization of the nanocomposite films was performed by employing wide angle X-ray diffraction (WAXD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) followed by image analysis. The results unfold a mixed morphology for the nanocomposite films with more than 95% exfoliated and intercalated silicate layer structures, depending on the screw rotation speed. The remarkable dispersion of the organoclay particles at the nano-level is discussed in terms of solubility parameter and favorable interactions between PET macromolecules and organic modifier of the nanoclay. The crystal content of the nanocomposite films and their cold and hot crystallization temperatures confirmed the role of silicate nanolayers as a heterogeneous nucleating agent. While all nanocomposite films exhibit higher haze values in comparison to the neat PET samples, incorporation of 2 wt% nanoclay brought about 25% increase in tensile modulus and barrier properties. A range of screw rotation speeds with optimized properties in terms of haze, morphology, thermal, mechanical, and barrier properties is suggested. Note de contenu : - Materials - Sample preparation - Characterization - Table 1 : DSC analysis results of the neat PET and nanocomposite films at various screw rotation speeds DOI : https://doi.org/10.1515/ipp-2020-4044 En ligne : https://drive.google.com/file/d/1UF1Q7xDZbldM1DEaaAvzkMvJsgouDJwq/view?usp=shari [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36708 [article]

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