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Effect of montmorillonite addition (modified and unmodified) on the structural, mechanical, thermal, and morphological properties of nanocomposites based poly(vinyl chloride) / Badra Bouchareb in MATERIAUX & TECHNIQUES, Vol. 110, N° 1 (13/06/2022)  

[article]  inMATERIAUX & TECHNIQUES > Vol. 110, N° 1 (13/06/2022) . - 12 p. Titre : Effect of montmorillonite addition (modified and unmodified) on the structural, mechanical, thermal, and morphological properties of nanocomposites based poly(vinyl chloride) Type de document : texte imprimé Auteurs : Badra Bouchareb, Auteur ; Nacerddine Haddaoui, Auteur ; Sarwat Zahra, Auteur Année de publication : 2022 Article en page(s) : 12 p. Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Argile Chlorure de polyvinyle Composites thermoplastiques -- Propriétés physiques Montmorillonite Nanoparticules Index. décimale : 668.4 Plastiques, vinyles Résumé : Poly(vinyl chloride)/ montmorillonite nanocomposites were prepared using a melt mixing technique. For this purpose, three montmorillonite samples (MMT) namely, raw montmorillonite (R-MMT), sodium montmorillonite (Na+-MMT) and organically modified montmorillonite (O-MMT) were used with different contents (0, 1, 3, 5, 7 and 9 phr) in the presence of dioctyl phthalate (DOP). X-Ray Diffraction (XRD), Atomic Force Microscopy (AFM), Differential Scanning Calorimetry (DSC), and mechanical testing were used to investigate the physical properties of nanocomposites (PVC/MMT). The results of XRD show that macromolecule chains of PVC may be intercalated or exfoliated into the gallery of modified montmorillonite (Na+-MMT and O-MMT). Microcomposites structure is formed on the PVC/R-MMT nanocomposites when the unmodified montmorillonite (R-MMT) content is added from 1 to 9 phr. However, the glass transition temperature (Tg) of PVC/O-MMT nanocomposites is shifted slightly to lower temperatures. Furthermore, O-MMT plays the role of an internal plasticizer hence increases the distance between macromolecule chains of the polymer. Consequently, the degree of interactions between the chains decreases inducing a decrease in Tg. Synergy effect is also observed on the PVC/O-MMT nanocomposites with the increase in the amount of O-MMT. The morphological study by AFM shows a reduction in surface roughness under the effect of montmorillonite modified, and particularly with (1 phr) of O-MMT. Note de contenu : - MATERIALS AND METHODS : Material - Preparation of PVC/MMT nanocomposite - METHODS : X-ray diffraction (XRD) - Tensile test - Hardness - Differential Scanning Calorimetry (DSC) - Atomic Force Microscopy (AFM) - RESULTS AND DISCUSSION : X-ray diffraction (XRD) - Tensile test - Hardness test - Differential Scanning Calorimetry (DSC) - Atomic Force Microscopy (AFM) - Table 1 : Formulations realized with R-MMT, Na+ -MMT and O-MMT - Table 2 : Tensile properties of PVC/R-MMT, PVC/Na + -MMT and PVC/O-MMT nanocomposites with modified and unmodified MMT - Table 3 : Results of DSC analysis (glass transition temperature) of PVC films and its nanocomposites - Table 4 : RMS values of different nanocomposites Référence de l'article : 103 DOI : https://doi.org/10.1051/mattech/2022011 En ligne : https://www.mattech-journal.org/articles/mattech/pdf/2022/01/mt210028.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=37814 [article]

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Cementitious composites incorporating Multi-Walled Carbon Nanotubes (MWCNTs): effects of annealing and other dispersion methods on the electrical and mechanical properties / Shaban Shahzad in MATERIAUX & TECHNIQUES, Vol. 110, N° 1 (13/06/2022)  

[article]  inMATERIAUX & TECHNIQUES > Vol. 110, N° 1 (13/06/2022) . - 14 p. Titre : Cementitious composites incorporating Multi-Walled Carbon Nanotubes (MWCNTs): effects of annealing and other dispersion methods on the electrical and mechanical properties Type de document : texte imprimé Auteurs : Shaban Shahzad, Auteur ; Ahmed Toumi, Auteur ; Jean-Paul Balayssac, Auteur ; Anaclet Turatsinze, Auteur ; Vanessa Mazars, Auteur Année de publication : 2022 Article en page(s) : 14 p. Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Composites -- Propriétés électriques Composites -- Propriétés mécaniques Dispersions et suspensions Matériaux cimentaires -- Additifs 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. Index. décimale : 620.13 Matériaux de construction : pierre, ciment, béton, liants de Résumé : This study focuses on different techniques for dispersing Multi-Walled Carbon Nanotubes (MWCNTs) in cementitious materials. The impact of dispersion is observed through electrical resistivity and mechanical properties of cementitious composites. Two contents (0.5 and 1% by mass of cement) of MWCNTs are investigated and three different techniques were used to disperse CNTs in water by sonication: (i) pristine, P-CNT, (ii) functionalized carbon nanotubes by classical approach (dispersive agent, D-CNT), and (iii) by an innovative approach (annealing, A-CNT). Self-sensing response of the material under cyclic compressive loading is measured with Wheatstone Bridge (WSB) circuit. Results showed a detrimental effect of dispersive agent on the resistivity and mechanical properties of cementitious composites irrespective of the content of CNTs. However, the impact of P-CNT and A-CNT on the reduction of mechanical properties is slight. With the use of 1% content of A-CNTs, a stable resistivity response of the material is observed irrespective of the saturation degree. This indicates that content higher than 1% of A-CNTs is not required for the development of smart cementitious composites for structural health monitoring (SHM). The test results of self sensing measurements indicate a poor repeatability of the electrical response for plain mortar under each loading cycle while, stable response is noticed with specimens incorporating 1% of A-CNTs. The maximum variation in fractional change in voltage (FCV) shown by plain mortar is 6.3% indicating high electrical resistance of plain mortar, while in case of mortar containing 1% A-CNTs, variation in FCV is 35% indicating lower electrical resistance and better sensitivity of the material. Note de contenu : - MATERIALS AND METHODS : Materials - Methods adopted for dispersion - Preparation of specimens - TESTING PROCEDURES : Assessment of dispersion of CNT in solution - Resistivity assessment on mortars - Mechanical properties - Self-sensing test - RESULTS AND DISCUSSION : Electrical properties - Mechanical properties - Self-sensing test - Table 1 : Physical properties and chemical composition of Portland cement (CEM I 52.5R) - Table 2 : Physical properties and chemical composition of normalized sand - Table 3 : Properties of MWCNTs - Table 4 : Nomenclature of the mortar specimens - Table 5 : Voltage and resistance at the balanced condition of WSB circuit Référence de l'article : 104 DOI : https://doi.org/10.1051/mattech/2022020 En ligne : https://www.mattech-journal.org/articles/mattech/pdf/2022/01/mt210072.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=37815 [article]

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