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Functionalisation of multi-walled carbon nanotubes (MWCNT) using 1,3,5-triazine: Characterisation of thermal stability and chemical structure and effect of thermal properties of epoxy resins

Luis Antonio S. De Almeida Prado 1Alejandra de la Vega Jan Sumfleth Karl Schulte 

1. Technical University Hamburg-Harburg (TUHH), Denickestr. 15, Hamburg 21073, Germany

Abstract

In the present communication we report the functionalisation of MWCNT using a 1,3,5-triazine, namely melamine. The MWCNTs (Baytubes, Germany) were dispersed in ethanol for 16 hours and allowed to react with melamine at 80°C for 1 hour or 16 hours. The resulting MWCNT-melamine adducts were heated at 250°C under vacuum in order to remove the non-chemisorbed melamine. Thermogravimetric and elemental analyses indicated that a 16 hour vacuum treatment was enough to remove almost 95% of the melamine present in the original adduct. The nitrogen-content of sample decreased from 0.017 mol/gram (for the MWCNT-melamine adduct) to 0.002 mol/gram (the adduct was heated for 16 hours under vacuum). During the treatment at 250°C the melamine can also interact further with the MWCNT yielding either to a physical mixture, or the product of cycloaddition reactions between the 1,3,5-triazine rings and the MWCNTs. Based on the strong resemblance of the Raman spectra of the pristine MWCNTs with that of the MWCNT-melamine, i.e. all samples have spectra with the same intensity for the D and G bands, we suppose that the 1,3,5-triazine rings interact with the graphene layers of MWCNTs by the so-called p-p interactions. Therefore all materials prepared in this work can be regarded as non-covalently functionalised MWCNTs.

The functionalisation of MWCNTs with melamine can bring about enhanced interactions with polymeric matrices. For instance, differential scanning calorimetry results indicated a +10°C shift of the glass transition temperature of an epoxy resin based on bisphenol A (DER 331, Dow Chemical, Germany) and an amine hardener (A2954, Huntsman, Germany) at loading close to 0.10 wt-%. The similar nanocomposite containing 0.10-wt% of pristine MWCNT has a glass transition temperature slightly lower than the neat resin, which is in accordance with previous publications of our group [1].

References:

[1] J. Sumfleeth, L. A. S. A. Prado, M. Sriyai, K. Schulte Adv. Funct. Mater. 2008 (submitted)

 

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Related papers

Presentation: Oral at E-MRS Fall Meeting 2008, Symposium F, by Luis Antonio S. De Almeida Prado
See On-line Journal of E-MRS Fall Meeting 2008

Submitted: 2008-05-07 15:33
Revised:   2009-06-07 00:48