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

Abstract

Polystyrene/poly(butylene adipate-co-terephthalate) (PS/PBAT) composites loaded with different amounts of carbon nanotube (CNT) were prepared by melt mixing followed by compression molding at different temperatures. The effect of the non-covalent functionalization of CNT with the ionic liquid (IL), trihexyl(tetra decyl)-phosphonium bis-triflimide on the electrical and rheological properties of the composites with co-continuous morphology was investigated. The AC electrical conductivity of the composites loaded with 0.16 wt.% of pristine CNT jumped from 10 −7 to 10 −3 S/m by increasing the molding temperature from 180 to 200 • C. Moreover, conductivity as high as 0.8 S/m was achieved in composite containing 0.66 wt.% of CNT. The outstanding electrical performance was attributed to the double percolation and the selective localization of CNT within PBAT phase. The functionalization with IL resulted in an increase of the conductivity for composites containing low amount of filler. IL-functionalized CNT resulted in a decrease of the melt viscosity and storage modulus due to the plasticizing effect of IL. However, for the system containing IL/CNT = 5:1 wt.%, the modulus increased significantly due to the formation of the percolated networked structure of the filler within the polymer matrix.

Ultra-Low Percolation Threshold Induced by Thermal Treatments in Co-Continuous Blend-Based PP/PS/MWCNTs Nanocomposites

“…In this case, the reduction in PT can be achieved thanks to a double percolation effect, resulting from the co-continuous morphology of the used PB [ 6 , 9 , 24 , 25 , 26 ]. Furthermore, the reduction in PT can be achieved through both covalent and noncovalent modifications of either CNTs or matrices of CNTs-based thermoplastic composites with co-continuous morphology [ 7 , 25 , 28 ]. Some researchers suggested adding different nanoparticles to help trap CNTs at the interface [ 41 , 46 ].…”

“…Conductive nanocomposites are obtained by dispersing electrically conductive nanoparticles (particles with at least one of their dimensions ranging from 1 to 100 nm) within a matrix. The most used nanoparticles to obtain electrically conductive polymers are carbon black (CB) [ 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ], carbon nanotubes (CNTs) [ 2 , 3 , 4 , 5 , 6 , 7 , 8 , 24 , 25 , 26 , 27 , 28 ], and graphene [ 12 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 ]. Due to the advantages conductive thermoplastic composites present, significant research has been conducted towards achieving certain desired properties at low filler concentrations, primarily by reducing the percolation threshold (PT).…”

“…For example, Chen, J. et al have shown that introducing 5 wt.% of SEBSg-MA in PP/PS (70/30 wt.%) co-continuous matrix reduces PT from 1.22 wt.% for PP/PS/MWCNTs to 0.66 wt.% for PP+SEBS-g-MA/PS/MWCNTs [ 44 ]. Other additives like graphene, graphene oxide (GO), organoclay, CB, noncovalent and covalent modifiers were also reported in the literature to reduce the PT of PB/CNTs co-continuous systems [ 9 , 11 , 24 , 28 , 41 , 45 , 46 , 47 ].…”

Waste to Value-Added Product: Developing Electrically Conductive Nanocomposites Using a Non-Recyclable Plastic Waste Containing Vulcanized Rubber

“…Double percolation is achieved when selective localization and confinement of the conductive filler within a co-continuous structure (e.g., phase or interface of binary blends) leads to significant enhancement in the conductive network. Many studies tried to develop such an excluded volume-based morphology in immiscible polymer blends [ 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 ] and semi-crystalline polymers [ 72 , 73 , 74 , 75 ] through modification of processing condition, blend composition, and thermodynamic affinity between polymers and filler. The advantage of our strategy over other methods is achieving a percolated structure of CNTs by a simple melt mixing process with no need of any modification or introduction of any other expensive polymeric component.…”

“…In a system with double percolation morphology, the filler particles form an interconnected conductive network (i.e., percolation) and the minor phase constructs a co-continuous structure. This leads to a reduction in the usage of costly conductive filler and provides more flexibility in the tuning of the final properties of conductive nanocomposite for a specific application of interest [ 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 ]. The waste material, carbon nanotube (CNT), and polystyrene (PS) were melt-blended at different compositions, and the compression molded samples were prepared for electrical conductivity, EMI shielding, optical microscopy, and rheological characterizations.…”