Effects of Surface Modification of MWCNT on the Mechanical and Electrical Properties of Fluoro Elastomer/MWCNT Nanocomposites

Tao Xu,Jinghui Yang

doi:10.1155/2012/275637

Abstract

Surface modification is a good way to improve the surface activity and interfacial strength of multiwalled carbon nanotubes (MWCNTs) when used as fillers in the polymer composites. Among the reported methods for nanotube modification, mixed acid oxidation and plasma treatment is often used by introducing polar groups to the sidewall of MWCNT successfully. The purpose of this study is to evaluate the effect of different surface modification of MWCNT on the mechanical property and electrical conductivity of Fluoro-elastomer (FE)/MWCNT nanocomposites. MWCNTs were surface modified by mixed oxidation and CF4plasma treatment and then used to reinforce the fluoro elastomer (FE, a copolymer of trifluorochloroethylene and polyvinylidene fluoride). FE/MWCNT composite films were prepared from mixture solutions of ethylacetate and butylacetate, using untreated CNTs (UCNTs), acid-modified CNTs (ACNTs), and CF4plasma-modified CNT (FCNTs). In each case, MWCNT content was 0.01 wt%, 0.05 wt%, 0.1 wt%, and 0.2 wt% with respect to the polymer. Morphology and mechanical properties were characterized by using scanning electron microscopy (SEM), Raman spectroscopy, as well as dynamic mechanical tests. The SEM results indicated that dispersion of ACNTs and especially FCNTs in FE was better than that of UCNTs. DMA indicated mechanical properties of FCNT composites were improved over ACNT and UCNT filled FE. The resulting electrical properties of the composites ranged from dielectric behavior to bulk conductivities of 10-2 Sm-1and were found to depend strongly on the surface modification methods of MWCNTs.

Highlights

CNT/polymer nanocomposites hold the promise of delivering exceptional mechanical properties and multifunctional characteristics [1, 2], the scope of CNT applications in practical devices has been largely hampered by their poor dispersibility in polymer resin and weak interfacial bonding with polymer matrix
We report on our attempts to understand the relationship between the surface modification of carbon nanotubes and the resulting mechanical property and the electrical conductivity of the nanocomposites
After being modified by CF4 plasma, more new peaks appear with higher binding energy and are attributed to fluorinated species: C–C, C–CF, C–O, C–O–F, and C–F, which indicates that CF4 plasma can induce grafting of CFx or depositing of a layer of fluorine polymer onto multiwalled carbon nanotubes (MWCNTs) successfully

Summary

Introduction

CNT/polymer nanocomposites hold the promise of delivering exceptional mechanical properties and multifunctional characteristics [1, 2], the scope of CNT applications in practical devices has been largely hampered by their poor dispersibility in polymer resin and weak interfacial bonding with polymer matrix. Ineffective interfacial bonding and sliding of individual nanotubes within the ropes inhibit load transfer from the matrix to the fillers in the composite, making the amount of mechanical reinforcement unachievable in polymer composites [3,4,5,6]. Modification introduces suitable covalent bonds on the sidewalls of CNTs, by which the chemical bondings in the interface between the CNT and the polymer matrix can be obtained [7,8,9]

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Conclusion