Dispersion and distribution of carbon nanotubes in ternary rubber blends

doi:10.1016/j.compscitech.2013.11.008

Composites Science and Technology

Volume 90, 10 January 2014, Pages 180-186

https://doi.org/10.1016/j.compscitech.2013.11.008 Get rights and content

Abstract

Structure and morphology of carbon nanotubes (CNTs) filled ternary styrene butadiene rubber (SBR)/nitrile butadiene rubber (NBR)/natural rubber (NR) blends were characterized quantitatively by means of the wetting concept und qualitatively supported by transmission electron microscopy (TEM) and atomic force microscopy (AFM). It was found that CNTs mainly reside in the polar NBR and non-polar NR but not in weak polar SBR. Such unusual localization of CNTs in ternary SBR/NBR/NR can be explained by taking into consideration the presence of phospholipids in NR. Phospholipid can act as coupling agent bonding the α-terminal of NR with the CNT surface through cation-π interactions, which make NR be competitive with NBR with respect to CNT hosting. Setting the equilibrium CNT loadings experimentally determined by the wetting concept into the Z-model recently developed in our previous work by keeping unchanged the surface tension values of SBR and NBR a corrected value of surface tension of NR was determined, which involves the effect of phospholipids.

Introduction

Carbon nanotubes (CNTs) have a wide range of potential applications in many industrial areas because of their outstanding electrical and mechanical properties. Recently, they have been used as filler in rubber and rubber blends to create new functionalities and/or to improve various properties of tire tread compounds [1], [2], [3]. Generally, it is well-known that a good dispersion and homogeneous phase selective distribution of filler in polymer blends are necessary for optimization of composite properties [4], [5], [6], [7], [8], [9], [10], [11]. While the selective filler localization and its effect on mechanical and electrical properties of CNT filled thermoplastic/thermoplastic blends have been comprehensively characterized [4], [5], [6], [7], it is still incomplete in the field of rubber/rubber blends so far [8], [9], [10], [11]. Furthermore, polymer blends containing more than two rubber components have been prepared with filler in order to obtain synergistic properties of composites [12], [13], [14], [15]. For instance, ternary blends on the basis of natural rubber (NR), butadiene rubber (BR) and ethylene propylene diene rubber (EPDM) were used for tire sidewalls showing excellent ultimate properties, better ozone resistance and fatigue resistance under dynamic load [13]. The dispersion and phase specific distribution of CNTs in ternary blends have not been characterized so far because of the lack of suitable testing methods. In the present work we used the method of the online measured electrical conductance and wetting concept as well as Z-model, which were further developed for ternary blends [16], [17] for characterization of the kinetics of CNT dispersion and distribution in ternary blends based on styrene butadiene (SBR), nitrile butadiene rubber (NBR) and NR.

Section snippets

Materials and mixture preparation

Solution styrene butadiene rubber (S-SBR) used was SPRINTAN SLR-4601 (Styron Deutschland GmbH) with a styrene content of 21% and vinyl content of 63%. Nitrile butadiene rubber (NBR) Perbunan 3445F (Lanxess) with a nitrile content of 34% and natural rubber (NR) SMR10 (Standard Malaysian Rubber, Weber & Schaer GmbH) were also used. NR was masticated by means of two-roll mill before use in order to obtain a similar Mooney viscosity value as the other blend partners. Multi-walled carbon nanotubes

Online measured electrical conductance and CNT macrodispersion

The online conductance curves of different rubbers containing 5 phr CNTs without and with ethanol recorded during the mixing are presented in Fig. 1a. Without ethanol, SBR and NR show no electrical signal (curves 1 and 3), that indicates there is no percolated conduction filler network in rubbers because of the bad filler dispersion.

For CNT filled NBR an online conductance curve was recorded (curve 2), which shows a typical conductance-time characteristics with t_onset = 17 min and t_Gmax = 30 min. At t

Conclusions

The phase specific distribution of CNTs in ternary SBR/NBR/NR blends was experimentally determined using the wetting concepts. It was found that the CNT distribution after long mixing time of about 50 min is the same for four blends prepared by different mixing regimes. The unusual high value of CNT loading in the non-polar NR phase was explained by taking into consideration the presence of phospholipids. Phospholipid can act as coupling agent bonding the α-terminal of NR with the CNT surface

Acknowledgements

The authors wish to thank the Deutsche Forschungsgemeinschaft (DFG) (Project No. LE 3202/1-1) and Ministerium für Wirtschaft und Arbeit des Landes Sachsen-Anhalt (Project No. 1304/00022) for the financial support.

References (26)

H.H. Le et al.
Kinetics of filler wetting and dispersion in carbon nanotube/rubber composites
Carbon
(2012)
A. Das et al.
Modified and unmodified multiwalled carbon nanotubes in high performance solution styrene butadiene and butadiene rubber blends
Polymer
(2008)
K.W. Stöckelhuber et al.
Contribution of physico-chemical properties of interfaces on dispersibility, adhesion and flocculation of filler particles in rubber
Polymer
(2010)
P. Verge et al.
Investigation on the dispersion of carbon nanotubes in nitrile butadiene rubber: role of polymer-to-filler grafting reaction
Compos Sci Technol
(2010)
L. Bokobza et al.
Blends of carbon blacks and multiwall carbon nanotubes as reinforcing fillers for hydrocarbon rubbers
J Appl Polym Sci
(2008)
OhWS, Choi WJ, Choi YH, Park J, Lee YS. Nanotechnology 2009: biofuels, renewable energy, coatings, fluidics and compact...
A. Boonmahitthisud et al.
NR/XSBR nanocomposites with carbon black and carbon nanotube prepared by latex compounding
J Met Mater Miner
(2012)
D. Wu et al.
Selective distribution of nanofillers: effect on morphology and crystallization of PLA/PCL blends
Macromol Chem Phys
(2011)
Y. Sun et al.
Effect of ABS rubber content on the localization of MWCNTs in PC/ABS blends and electrical resistivity of the composites
Macromol Mater Eng
(2010)
A. Göldel et al.
Selective localization and migration of multiwalled carbon nanotubes in blends of polycarbonate and poly(styrene-acrylonitrile)
Macromol Rapid Commun
(2009)

S.K. Lim et al.

Ternary poly(styrene-co-acrylonitrile)/poly(vinyl chloride) blend composites with multi-walled carbon nanotubes and enhanced physical characteristics

Macromol Mater Eng

(2010)

J.S. Hong et al.

Dispersion of MWCNT in PDMS/PB

Rheol Act

(2011)

A. Boonmahitthisud et al.

Use of CNT and nano silica in NR/SBR blends latex

Adv Mater Res

(2012)

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Dispersion and distribution of carbon nanotubes in ternary rubber blends

Abstract

Introduction

Section snippets

Materials and mixture preparation

Online measured electrical conductance and CNT macrodispersion

Conclusions

Acknowledgements

Carbon

Polymer

Polymer

Compos Sci Technol

Blends of carbon blacks and multiwall carbon nanotubes as reinforcing fillers for hydrocarbon rubbers

J Appl Polym Sci

NR/XSBR nanocomposites with carbon black and carbon nanotube prepared by latex compounding

J Met Mater Miner

Selective distribution of nanofillers: effect on morphology and crystallization of PLA/PCL blends

Macromol Chem Phys

Effect of ABS rubber content on the localization of MWCNTs in PC/ABS blends and electrical resistivity of the composites

Macromol Mater Eng

Selective localization and migration of multiwalled carbon nanotubes in blends of polycarbonate and poly(styrene-acrylonitrile)

Macromol Rapid Commun

Ternary poly(styrene-co-acrylonitrile)/poly(vinyl chloride) blend composites with multi-walled carbon nanotubes and enhanced physical characteristics

Macromol Mater Eng

Dispersion of MWCNT in PDMS/PB

Rheol Act

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Adv Mater Res