Basic study of extensional flow mixing for the dispersion of carbon nanotubes in polypropylene by using capillary extrusion / K. Matsumoto in INTERNATIONAL POLYMER PROCESSING, Vol. 36, N° 4 (2021)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. 36, N° 4 (2021) . - p. 379-387 Titre : Basic study of extensional flow mixing for the dispersion of carbon nanotubes in polypropylene by using capillary extrusion Type de document : texte imprimé Auteurs : K. Matsumoto, Auteur ; T. Tanaka, Auteur Année de publication : 2021 Article en page(s) : p. 379-387 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Charges (matériaux) Dispersions et suspensions Extrusion capillaire Matières plastiques -- Extrusion Mélange Nanotubes Polypropylène Rhéologie Viscoélasticité Index. décimale : 668.4 Plastiques, vinyles Résumé : This study evaluated the mixing effect of simple uniaxial extensional flow for the dispersion of multiwalled carbon nanotubes (MWCNTs) into polypropylene (PP) as a nonpolar matrix. An only converging flow allowed for a high strain rate and was suitable for the compounding process. The extensional flow was characterized from the entrance pressure drop (ΔP0) at the converging section. Thus, in this study, capillary extrusion was employed to generate uniaxial extensional flow. Based on the hypothesis that the dispersion of nanofillers depends on the magnitude of flow-induced stress, ΔP0, which related to extensional stress, was measured directly during capillary extrusion by using an orifice die. The influences of the mass flow rate and the hole diameter in the orifice die, which affected ΔP0, on the extrusion of PP nanocomposites with an MWCNT loading of 1.0 wt.% were studied. The extruded samples were collected, and the dispersion state was evaluated based on the melt viscoelastic properties, volume resistivity, and morphological observations by optical microscopy (OM) and transmission electron microscopy (TEM). The agglomeration area of the MWCNTs decreased with higher ΔP0 (higher mass flow rate and smaller hole diameter), which increased the uniformity of the dispersion. Moreover, the influence of the length-to-diameter (L/D) ratio of the hole in the capillary die on the dispersion state of the MWCNTs was investigated. A higher L/D ratio of the capillary die did not improve the dispersion state, although shear and extensional stresses were provided. Note de contenu : - Introduction - Theory - Experimental : Materials and preparation of the nanocomposite - Capillary extrusion - Evaluation of the dispersion state - RESULTS AND DISCUSSION : Rheological properties in capillary extrusion - Morphological assessment of the dispersion state - Viscoelastic properties and volume resistivity - Comparison of orifice die and capillary die - Table 1 : The conditions of piston speed and mass flow rate Q for capillary extrusion at a constant temperature of 200°C - Table 2 : Entrance pressure drop (ΔP0) and pressure drop inside the capillary hole (ΔPcap) as a function of the different hole diameters DOI : https://doi.org/10.1515/ipp-2020-4022 En ligne : https://drive.google.com/file/d/1aEEaI2_RyG8J1romHG2erjvLumHzgEnT/view?usp=shari [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36710 [article]

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