410
Y. Bolbukh et al.
layer was maintained at 30% of each type of group. The degree of substitution of
isolated silanols on the silica surface with functional groups was controlled by IR
spectroscopy.
26.2.3 Preparation of Silica/Lignin Composites
For the silica impregnation, the water-soluble lignin (150 mg) was dissolved in
deionized water (20 ml) and then mixed with dry powder (500 mg) at room
temperature. Obtained paste was left without disturbing overnight and dried at 80 ◦ C
for 12–17 h. The polymer content in organic/inorganic composite was 20 wt%. The
sample description is presented in Table 26.1.
26.2.4 Analytic Technique
Fourier transform infrared (FTIR) spectroscopy (Thermo Nicolet Nexus FTIR) has
been used to characterize the silica surface. The dispersed samples were mixed with
KBr (1:100). The FTIR spectra were obtained by recording 50 scans between 4000
and 400 cm −1 with a resolution of 8 cm −1 .
The UV–vis absorption measurements were performed with a UV–vis spectrophotometer Cary 4000 (Varian, Australia). Deionized water was scanned at the
same wavelength as a baseline.
Infrared spectra ATR was carried out on a STA 449 Jupiter F1, NETZSCH
(Germany). Spectra were recorded in the spectral range of 600–4000 cm −1 with
16 scans per spectrum at a resolution of 4 cm −1 and have been used to characterize
the silica/lignin composites.
Thermal properties and stability of the surface layer were studied using differential scanning calorimetry (DSC) that was performed under nitrogen atmosphere in
the temperature range from 20 up to 480 ◦ C using a NETZSCH DSC 204F1 Phoenix
instrument (Germany). Samples of ∼8–16 mg in mass were closed in standard Tzero
aluminum pans. Cooling and heating rates were 10 ◦ C/min. During the first heating
scan, the samples stayed at 120 ◦ C for 5 min (isothermally) and during the second
heating scan, at 20 ◦ C for 3 min in order to stabilize the materials.
Relaxation process and phase transitions in the polymer immobilized on the silica
surface were investigated in nitrogen atmosphere in the temperature range from −50
to 350 ◦ C using a Perkin Elmer Pyris 6 DSC instrument, calibrated with indium for
temperature and enthalpy. Samples of 8 mg in mass were closed in aluminum pans.
Cooling and heating rates were fixed to 20 K/min. A first heating scan (heating 1)
from room temperature (30 ◦ C) to 150 ◦ C was performed for evaporating water and
remaining solvents. Then the sample was cooled to −50 ◦ C, and then, the second
DSC scan (heating 2) up to 350 ◦ C was performed. For pure lignin additional scans
were performed (up to 150 to 250 and to 350 ◦ C) on a second fresh sample.
Y. Bolbukh et al.
layer was maintained at 30% of each type of group. The degree of substitution of
isolated silanols on the silica surface with functional groups was controlled by IR
spectroscopy.
26.2.3 Preparation of Silica/Lignin Composites
For the silica impregnation, the water-soluble lignin (150 mg) was dissolved in
deionized water (20 ml) and then mixed with dry powder (500 mg) at room
temperature. Obtained paste was left without disturbing overnight and dried at 80 ◦ C
for 12–17 h. The polymer content in organic/inorganic composite was 20 wt%. The
sample description is presented in Table 26.1.
26.2.4 Analytic Technique
Fourier transform infrared (FTIR) spectroscopy (Thermo Nicolet Nexus FTIR) has
been used to characterize the silica surface. The dispersed samples were mixed with
KBr (1:100). The FTIR spectra were obtained by recording 50 scans between 4000
and 400 cm −1 with a resolution of 8 cm −1 .
The UV–vis absorption measurements were performed with a UV–vis spectrophotometer Cary 4000 (Varian, Australia). Deionized water was scanned at the
same wavelength as a baseline.
Infrared spectra ATR was carried out on a STA 449 Jupiter F1, NETZSCH
(Germany). Spectra were recorded in the spectral range of 600–4000 cm −1 with
16 scans per spectrum at a resolution of 4 cm −1 and have been used to characterize
the silica/lignin composites.
Thermal properties and stability of the surface layer were studied using differential scanning calorimetry (DSC) that was performed under nitrogen atmosphere in
the temperature range from 20 up to 480 ◦ C using a NETZSCH DSC 204F1 Phoenix
instrument (Germany). Samples of ∼8–16 mg in mass were closed in standard Tzero
aluminum pans. Cooling and heating rates were 10 ◦ C/min. During the first heating
scan, the samples stayed at 120 ◦ C for 5 min (isothermally) and during the second
heating scan, at 20 ◦ C for 3 min in order to stabilize the materials.
Relaxation process and phase transitions in the polymer immobilized on the silica
surface were investigated in nitrogen atmosphere in the temperature range from −50
to 350 ◦ C using a Perkin Elmer Pyris 6 DSC instrument, calibrated with indium for
temperature and enthalpy. Samples of 8 mg in mass were closed in aluminum pans.
Cooling and heating rates were fixed to 20 K/min. A first heating scan (heating 1)
from room temperature (30 ◦ C) to 150 ◦ C was performed for evaporating water and
remaining solvents. Then the sample was cooled to −50 ◦ C, and then, the second
DSC scan (heating 2) up to 350 ◦ C was performed. For pure lignin additional scans
were performed (up to 150 to 250 and to 350 ◦ C) on a second fresh sample.