8 Nanocomposites Based on Thermosetting Polyurethane Matrix. . .
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8.2.2.2 Atomic Force Microscopy (AFM)
Surface topography and phase images of PU and nanocomposites were obtained
using a multimode Nanoscope IIIa atomic force microscope. Tapping mode was
employed in air using a 125 μm silicon tip. Topographic and phase images were
obtained simultaneously.
8.2.2.3 Transmission Electron Microscopy (TEM)
To enable TEM investigations, the nanocomposite samples were dehydrated in an
ethanol series, passed through the transition solvent propylene oxide and embedded
in TAAB Low Viscosity resin (TAAB Laboratories Ltd., Aldermaston, UK). Thin
(100 nm) sections were cut on a Leica Ultracut ultramicrotome (Leica Microsystems
[UK] Ltd., Milton Keynes UK), collected on nickel support grids and examined
unstained in a Hitachi-7100 TEM at 100 kV. Images were acquired digitally with an
axially mounted (2 K × 2 K pixel) Gatan Ultrascan 1000 CCD camera (Gatan UK,
Oxford, UK).
8.2.2.4 Scanning Electron Microscopy (SEM)
Electron micrographs were obtained using Hitachi S-4800 CFE scanning electron
microscope. Samples of nanocomposites were fractured in liquid nitrogen and
chemically treated with aqueous iodine and potassium iodide. They were subsequently freeze-dried overnight before being examined by electron microscopy. Two
sets of samples were examined: in the first set, samples were sputtered with gold to
avoid electrostatic charging, and in the second set, samples were not coated.
8.2.2.5 Mechanical Testing
Mechanical properties of the nanocomposites were measured using a Series IX
Automated Instron Materials Testing System. The samples were cut into micro
dumb-bell shapes with gauge length of 20 mm, widths between 4–5 mm and sample
thickness between 0.7–0.9 mm. Samples were processed at a continuous strain rate
of 25 mm/min.
8.2.2.6 Dynamic Mechanical Analysis (DMA)
Dynamic mechanical behaviour of nanocomposites was analyzed in tension mode,
basically at 1 Hz, using a Dynamic Mechanical Spectrometer DMS 6100 Seiko
Instruments (Japan) at temperatures from −120 to +190 ◦ C. Film samples with
0.6 × 10 mm 2 cross-section and 2-cm working length were used. A sample was
121
8.2.2.2 Atomic Force Microscopy (AFM)
Surface topography and phase images of PU and nanocomposites were obtained
using a multimode Nanoscope IIIa atomic force microscope. Tapping mode was
employed in air using a 125 μm silicon tip. Topographic and phase images were
obtained simultaneously.
8.2.2.3 Transmission Electron Microscopy (TEM)
To enable TEM investigations, the nanocomposite samples were dehydrated in an
ethanol series, passed through the transition solvent propylene oxide and embedded
in TAAB Low Viscosity resin (TAAB Laboratories Ltd., Aldermaston, UK). Thin
(100 nm) sections were cut on a Leica Ultracut ultramicrotome (Leica Microsystems
[UK] Ltd., Milton Keynes UK), collected on nickel support grids and examined
unstained in a Hitachi-7100 TEM at 100 kV. Images were acquired digitally with an
axially mounted (2 K × 2 K pixel) Gatan Ultrascan 1000 CCD camera (Gatan UK,
Oxford, UK).
8.2.2.4 Scanning Electron Microscopy (SEM)
Electron micrographs were obtained using Hitachi S-4800 CFE scanning electron
microscope. Samples of nanocomposites were fractured in liquid nitrogen and
chemically treated with aqueous iodine and potassium iodide. They were subsequently freeze-dried overnight before being examined by electron microscopy. Two
sets of samples were examined: in the first set, samples were sputtered with gold to
avoid electrostatic charging, and in the second set, samples were not coated.
8.2.2.5 Mechanical Testing
Mechanical properties of the nanocomposites were measured using a Series IX
Automated Instron Materials Testing System. The samples were cut into micro
dumb-bell shapes with gauge length of 20 mm, widths between 4–5 mm and sample
thickness between 0.7–0.9 mm. Samples were processed at a continuous strain rate
of 25 mm/min.
8.2.2.6 Dynamic Mechanical Analysis (DMA)
Dynamic mechanical behaviour of nanocomposites was analyzed in tension mode,
basically at 1 Hz, using a Dynamic Mechanical Spectrometer DMS 6100 Seiko
Instruments (Japan) at temperatures from −120 to +190 ◦ C. Film samples with
0.6 × 10 mm 2 cross-section and 2-cm working length were used. A sample was