Morphology Evolution, Molecular Simulation, Electrical Properties, and Rheology of Carbon Nanotube/Polypropylene/Polystyrene Blend Nanocomposites: Effect of Molecular Interaction between Styrene-Butadiene Block Copolymer and Carbon Nanotube

Abstract

This work studied the impact of three types of styrene-butadiene (SB and SBS) block copolymers on the morphology, electrical, and rheological properties of immiscible blends of polypropylene:polystyrene (PP:PS)/multi-walled carbon nanotubes (MWCNT) with a fixed blend ratio of 70:30 vol.%. The addition of block copolymers to PP:PS/MWCNT blend nanocomposites produced a decrease in the droplet size. MWCNTs, known to induce co-continuity in PP:PS blends, did not interfere with the copolymer migration to the interface and, thus, there was morphology refinement upon addition of the copolymers. Interestingly, the addition of the block copolymers decreased the electrical resistivity of the PP:PS/1.0 vol.% MWCNT system by 5 orders of magnitude (i.e., increase in electrical conductivity). This improvement was attributed to PS Droplets-PP-Copolymer-Micelle assemblies, which accumulated MWCNTs, and formed an integrated network for electrical conduction. Molecular simulation and solubility parameters were used to predict the MWCNT localization in the immiscible blend. The simulation results showed that diblock copolymers favorably interact with the nanotubes in comparison to the triblock copolymer, PP, and PS. However, the interaction between the copolymers and PP or PS is stronger than the interaction of the copolymers and MWCNTs. Hence, the addition of copolymer also changed the localization of MWCNT from PS to PS–PP–Micelles–Interface, as observed by TEM images. In addition, in the last step of this work, we investigated the effect of the addition of copolymers on inter- and intra-cycle viscoelastic behavior of the MWCNT incorporated polymer blends. It was found that addition of the copolymers not only affects the linear viscoelasticity (e.g., increase in the value of the storage modulus) but also dramatically impacts the nonlinear viscoelastic behavior under large deformations (e.g., higher distortion of Lissajous–Bowditch plots).]

A Simple Approach to Control the Physical and Chemical Features of Custom-Synthesized N-Doped Carbon Nanotubes and the Extent of Their Network Formation in Polymers: The Importance of Catalyst to Substrate Ratio

“…The transition from linear viscoelastic to nonlinear viscoelastic region takes place at the critical strain amplitude (star symbols in Figure 8 ), characterized by the rapid decrease in storage modulus ( G ′) value. The reduction in G ′ is a direct consequence of nanofillers network break up and filler-matrix slippage, leading to a decrease in the number of load-bearing junctions [ 48 , 49 , 50 , 51 , 52 ]. Moreover, it was shown that, for a strong-linked network, the critical strain amplitude decreases to lower values by the introduction of more nanofillers into the polymer media [ 4 , 52 , 53 ].…”

“…The reduction in G ′ is a direct consequence of nanofillers network break up and filler-matrix slippage, leading to a decrease in the number of load-bearing junctions [ 48 , 49 , 50 , 51 , 52 ]. Moreover, it was shown that, for a strong-linked network, the critical strain amplitude decreases to lower values by the introduction of more nanofillers into the polymer media [ 4 , 52 , 53 ]. This is due to the higher sensitivity of the rigid 3D network structure of the nanofillers to the input deformation (i.e., strain amplitude) [ 53 , 54 ].…”

Interface Strengthening of PS/aPA Polymer Blend Nanocomposites via In Situ Compatibilization: Enhancement of Electrical and Rheological Properties

“…Therefore, to achieve an optimum network structure in the polymer blend nanocomposite during melt processing it is important to achieve an optimum dispersion within the matrix [15]. By addition of diblock, triblock and graft copolymer, the localization of CNT in a polystyrene/polypropylene (PS/PP) immiscible polymer blend was altered [16].…”

“…Many studies have shown that CNTs localization in polymer blends are primarily controlled by two major factors, thermodynamic [3,16,17] and kinetic [16,18] factors and these can be used to tune the final electrical properties of the multiphasic system.…”

Impact of hybrid nanofillers on the structure and property of polypropylene/polystyrene composites based on elongation flow

“…As a typical immiscible polymer system, the PP/PS blend has been studied extensively. The morphology and morphology evolution, rheological property, mechanical and electrical properties of PP/PS blends and modified composites have been investigated 5–8 . A number of compatibilizers have been applied to improve the interface interaction of PP/PS blend, such as benzoyl peroxide and maleic anhydride, 9 PP‐g‐MAH, 10 propylene‐co‐styrenic monomer copolymers, 11 PP‐g‐PS copolymer, 12 PS‐block‐poly(ethylene‐butylene)‐block‐PS copolymers 13 and nanoparticles 14–16 …”