Conducting melt blending of polystyrene and EVA copolymer with carbon nanotube assisted by phosphonium‐based ionic liquid

Abstract

Conducting composite materials, with electrical percolation threshold as low as 0.05–0.08 wt %, are prepared by incorporating multiwall carbon nanotube (CNT) in melt‐mixed co‐continuous polystyrene (PS)/ethylene‐vinyl acetate (EVA) copolymer (70:30 wt/wt) blend. CNT is found to be preferentially localized within the EVA phase, characterizing a double percolation phenomenon, which accounts for outstanding electrical conductivity (around 0.5 S/m with the addition of 1 wt % of CNT). The noncovalent functionalization of CNT with alkylphosphonium‐based ionic liquid results in composites with improved electrical conductivity (2.5 S/m with 1 wt % of CNT) and better electromagnetic interference shielding effectiveness. Both nonfunctionalized CNT (n‐CNT) or CNT with alkylphosphonium‐based ionic liquid contribute for a refinement of the co‐continuous structure, as indicated by scanning electron microscopy. The dispersion of CNTs and their physical networked structure within the polymer matrix are suggested by transmission electron microscopy and melt rheological experiments. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45564.

Double Percolation of Melt-Mixed PS/PBAT Blends Loaded With Carbon Nanotube: Effect of Molding Temperature and the Non-covalent Functionalization of the Filler by Ionic Liquid

“…The neat blend compression molded at higher temperature displayed a sea-island type morphology characterized by large PBAT domains (Figure 6b). The presence of CNT resulted in finer co-continuous morphology, which can be attributed to the change in the viscosity ratio between the blend components, as also reported in other CNT-loaded heterogeneous blends (Gao et al, 2017;Soares et al, 2018). The co-continuous structure is more difficult to observe for the blend compression-molded at 200 • C. The presence of IL-CNT also changes the morphology of the systems suggesting a compatibilizing action of this (Ph-TFSI) -based ionic liquid.…”

“…By choosing a blend composition whose phase containing the percolated conductive filler is continuous or a blend with co-continuous structure, the amount of required conductive filler for attaining the insulator-conducting transition (percolation threshold) is usually lower that that employed in single polymer matrix. This phenomenon is known as double percolation and has been reported for several CNT-loaded thermoplastic binary blends, including acrylonitrile-butadienestyrene (ABS) copolymers with PA6 (Poyekar et al, 2014(Poyekar et al, , 2015a, ABS/ polycarbonate (PC) (Xiong et al, 2013), poly(Llactide) (PLA)/(EVA) (Shi et al, 2013), PS/PP (Hwang et al, 2012), PS/PE (Patra et al, 2015), PS/polyvinylidene fluoride (PVDF) (Ren et al, 2017), PS/EVA (Soares et al, 2018), and PS/PLA (Nasti et al, 2016).…”

“…Some reports deals with the treatment of CNT with imidazolium-based ionic liquids to improve the dispersion of CNT in some thermoplastic matrices as well as, the filler-matrix interaction (Bellayer et al, 2005;Zhao et al, 2012;Sharma et al, 2014;Chen et al, 2015;Soares, 2018). Recently, alkyl phosphonium-based ionic liquids was also considered for assisting the CNT dispersion in polystyrene (PS) matrix (Soares da Silva et al, 2017), as well as polypropylene (PP)/polyamide12 (PA12) (Lopes Pereira et al, 2019) and PS/ ethylene-vinyl acetate copolymer (EVA) (Soares et al, 2018) blends. A significant increase in conductivity by several orders of magnitude was observed for PS/CNT composites using the trihexyl (tetradecyl) phosphoniumbistriflimide (Soares da Silva et al, 2017).…”

Epoxy/imidazolium‐based ionic liquid systems: The effect of the hardener on the curing behavior, thermal stability, and microwave absorbing properties

“…. ILs are known to improve the dispersion of conductive fillers giving rise to materials with better EMI shielding effectiveness (SE) . However, applications as coatings are limited due to the lack of transparency.…”

Carbon nanotube localization at interface in cocontinuous blends of polyethylene and polycarbonate

“…Carbon nanotubes (CNTs) are one of the best‐known conductive nanofillers . The interfacial tension Γ with a polymer can be estimated by the Girifalco–Good equation from the surface free energy γ . …”