Melt-mixed nanocomposites of SIS/MWCNT: rheological, electrical and structural behavior

Ludimilla Barbosa Ferreira,Rosario Elida Suman Bretas,João Paulo Ferreira Santos,Rayane De Souza Fernandes

doi:10.1590/0104-1428.08220

Abstract

Abstract In this work, nanocomposites based on the triblock copolymer polystyrene-b-polyisoprene-b-polystyrene (SIS) thermoplastic elastomer filled with multiwall carbon nanotubes (MWCNT) were obtained by melt mixing. The nanocomposites were characterized by oscillatory rheometry, electrical resistivity, small angle x-ray scattering (SAXS) and transmission electron microscopy (TEM). The results showed that both, rheological and electrical percolation were achieved at MWCNT loadings between 1-3 vol.%. Rheological tests revealed that the insertion of MWCNT into SIS significantly enhanced the process of relaxation of SIS blocks. Resistivity measurements revealed that conductive nanocomposites were obtained at MWCNT loadings ~1.6 vol.%. The electrical resistivity decreased eleven orders of magnitude from neat SIS to SIS/ 5 vol.% MWCNT. Finally, SAXS and TEM showed that the melt mixing process and the presence of MWCNT hampered the self-assembly of SIS into well-ordered domains.

Highlights

The use of multiwall carbon nanotubes (MWCNT) in polymeric matrixes to produce conductive nanocomposites has been widely studied[1,2]
The results showed that both, rheological and electrical percolation were achieved at MWCNT loadings between 1-3 vol.%
small angle x-ray scattering (SAXS) and transmission electron microscopy (TEM) showed that the melt mixing process and the presence of MWCNT hampered the self-assembly of SIS into well-ordered domains

Summary

Introduction

The use of multiwall carbon nanotubes (MWCNT) in polymeric matrixes to produce conductive nanocomposites has been widely studied[1,2]. Among the broad range of polymer matrixes, the thermoplastic elastomers have the advantage of behaving as elastomers at room temperature, but being able to be processed as thermoplastics[3] Their elastomeric properties make them good candidates for proton exchange membranes[4], sensors[5,6], photoactuators[7], among others. In a previous work of ours[3], flexible conductive nanocomposites based on the thermoplastic elastomer polystyrene-b-polybutadiene-bpolystyrene (SBS) filled with MWCNT were produced by solution casting followed by annealing during several days. These nanocomposites had a microstructure composed of hexagonally packed cylinders (HEX) co-existing with lamellar morphologies

Methods

Results

Conclusion