S 3400n machine

The nanoparticles’ dispersion in the MNP/epoxy mixtures was analyzed by light-transmitted optical microscopy (TOM) prior to the addition of the hardener, that is, before the curing step. A study of the influence of the sonication time on the dispersion state was carried out, taking samples after 15 min, 30 min, 1 h, 2 h, and 3 h of sonication. The microscope used was a Leica DMR (Leica Microsystems, Wetzlar, Germany) equipped with a camera, the Nikon Coolpix 990 (Nikon, Tokyo, Japan).
Furthermore, in order to evaluate the dispersion state obtained by these nanocomposites after the curing process, the analysis of the fracture surfaces under cryogenic conditions was performed by scanning electron microscopy (SEM) using an S–3400N machine from Hitachi. The nanocomposite cryofractures were coated by a thin layer of gold to achieve electrically conductive surfaces.

GNP/PDMS
nanocomposites were characterized by X-ray diffraction (XRD) and Fourier
transform infrared (FTIR) spectroscopy. X-ray diffraction was done
in a Panalytical X’Pert PRO diffractometer
with a Cu radiation source operating at 45 kV and 300 mA. The scanning
of 2θ was carried out from 10° to 90° in substeps
of 0.01. FTIR spectra were captured in a Varian Excalibur 3100 apparatus
(California, USA) in the wavenumber range of 4000–500 cm^–1 at 2 cm^–1 resolution.
The
dispersion of GNPs in the PDMS matrix was analyzed by observing cryogenic
fractures with scanning electron microscopy (SEM). For this purpose,
a Hitachi S-3400N machine was used. The samples were coated by sputtering
a thin layer of gold for proper microstructural observation.
Nonisothermal differential scanning calorimetry (DSC) tests were
carried out with a Mettler-Toledo 882e device from
−145 to 70 °C at 10 °C/min. Glass transition temperature
(T_g) was evaluated to analyze the influence
of the GNP content.