1. POLYMER/CARBON BASED FILLERS NANOCOMPOSITES: THERMOMECHANICAL AND SPECTROSCOPIC CHARACTERIZATION
A. Stimoniaris1,2*, E. Thomou2, D. Gournis2, M. Karakassides2 and C. Delides1
1Department of Environmental Engineering and Pollution Control, T.E.I. of Western Macedonia, Kozani, Greece
2Department of Materials Science and Engineering, University of Ioannina, Ioannina, Gre
7o Πανελλήνιο Συνέδριο
Θερμικής Ανάλυσης και Θερμιδομετρίας
Ιωάννινα, Μαΐου, 2016
INTRODUCTION
MATERIALS AND TECHNIQUES
Nanocomposites show different properties than the bulk polymer matrix because of the small size of the filler and the corresponding increase in their surface area [1-5].
It is well known that the composite properties can change with the dispersion state, geometric shape, surface properties, particle size, and particle size distribution. Recently, there is increasing interest for polymer nanocomposites with carbon based fillers.
These composites have been shown to undergo substantial improvements in mechanical properties such as the strength, modulus, and dimensional stability, permeability to gases, water and hydrocarbons, thermal stability, flame retardancy, chemical resistance, and electrical, dielectric, magnetic and optical properties [2,4].
The main aim of the present work is to study the thermomechanical and spectroscopic properties of nanocomposite materials based on epoxy resin (ER) matrix filled with the most used carbon based nanofillers (carbon black (CB), carbon nanotubes (MWCNTs) and graphene oxide (GO)).
Diglycidylether of bisphenol A (DGEBA) with triethylenetetramine (TETA) as hardener was the matrix material, while different amounts of carbon nanofillers (carbon black (CB), carbon nanotubes (MWCNTs) and graphene oxide (GO)) were used.
Sample preparation is described in details elsewhere [2]. All samples are used as they provided without any purification.
For the characterization of the nanocomposites, Scanning and Transmission Electron Microscopy, (SEM and TEM), Dynamic Mechanical Analysis (DMA), Thermogravimetric and Differential Scanning Calorimetry (DSC) measurements, Raman and IR spectroscopy techniques were carried out.
SCANING ELEKTRON MICROSCOPY (SEM)
THERMO - GRAVIMETRIC ANALYSIS (TGA)
SEM images for Epoxy Resin / nanocomposites
TGA plots and characteristic parameters for nanocomposites
Scanning electron microscopy was used to clarify the dispersion and the degree of aggregation/agglomeration of nano particulates in the matrix.
(1) Epoxy Resin
(2) ER/CB 2%
Comparative differential TGA curves for ER/CB and ER/MWCNTs nanocomposites filled with 0.5 w/w% of filler
Comparative DTGA plot for ER/CB 0.1% and ER/MWCNTs 0.1% nanocomposites
(3) ER/CNTs 0.1%
(4) ER/GO 0.5%
DYNAMIC MECHANICAL ANALYSIS (DMA)
DIFFERENTIAL SCANNING CALORIMETRY (DSC)
The dynamic mechanical properties (storage (E΄) and loss (E΄΄) moduli and glass transition (Tg))
of nanocomposites were assessed by dynamic mechanical analysis.
DSC curves for ER and ER/CNTs 0.01%
DSC curves for ER and ER/GO 0.1%
DSC measurements are employed to characterize the nanocomposites
CONCLUSIONS
The effect of carbon fillers
Basic properties of the composites are strongly depended on the shape, structure and the geometry of the filler particle.
The storage modulus (E΄) increases with filler content in the case of CB and decreases in the case of CNTs and GO.
Tg dependence follows almost the same way on the filler content for all fillers. Both dependences of E΄ and Tgs on the filler content may be attributed to the formation of a more flexible network in the case of CNTs and GO.
DSC spectra are consisted with DMA ones concerning the Tgs and there are evidences of chemical reactions between the amine groups of modified CNTs and the epoxy.
The results from TGA plots reveal that the samples show good thermal stability for temperatures up to 350 oC with a maximum decomposition temperature higher than 380 oC. It was found that the addition of nanofillers enhances the thermal properties of the epoxy matrix.
IR spectra of the composites contain several new bands. Some of the new bands correspond to amine molecules due to their interaction with CNTs and GO walls.
The characteristic peaks in Raman spectra of CNTs, namely the D band at 1330 cm-1 and the G band at 1580 cm-1 slightly change in position but significantly increased with filler content.
XRD patterns show differences due to different structures of the nanofillers.
SPECTROSCOPIC ANALYSIS
XRD patterns of Epoxy Resin and ER/omGO 0,1%
High frequency Raman spectra of CNTs and ER/CNTs composites
FT-IR spectra for Epoxy Resin and Nanocomposites
REFERENCES
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