462
B. M. Gorelov et al.
structure. The structural formula of the resin can be found elsewhere [27]. The resin
underwent no additional purification procedure before using. The epoxide to the
hardener ratio was kept to be constant at 5:1.
The multiplication of the dipoles may result from breaking amine cross-links
(ACLs) and shortening EMCs.
No efforts to orient MLG-NPs within the nanocomposites have been undertaken
in the present study because the orientation-related anisotropy may hinder to unveil
peculiarities of filler-epoxy interactions. The filler-mass-loadings (C f ) were 0.5, 1,
2, and 5% for both the nanocomposites. As prepared liquid composites of both the
types were mixed manually until homogeneous suspensions were obtained, and their
further polymerization occurred at room temperature during 72 h.
2.2 Experimental Techniques
Dielectric properties were obtained by measuring complex permittivity using the
computer-controlled impedance meter Hioki IM3536 General Purpose LCR Meter.
Details of the measuring technique can be found elsewhere [45]. The procedure of
preparation of samples is described in [46].
An impact of MLGNPs on thermal stability of the epoxy has been determined
by using a programmable thermal desorption technique combined with a massspectroscopic detection (TDMS) via the single-pole mass-analyzer MX 7304A.
Details of the measuring technique can be found elsewhere [47, 48].
The experimental values of the dynamic elastic modules of the epoxy and its
MLG-nanocomposites (namely, the Young’s modulus E, the compression modulus
M, the Lame constants λ and μ, and the Poisson’s ratio ν) have been calculated via
values of longitudinal (V L ) and shear (V S ) wave phase velocities (measured within
the frequency range of 1.5–2.0 MHz) and calculated values of the nanocomposite’s
density ρ by using a procedure described in [48]. The theoretical values of the
modules have been calculated by using the molecular dynamic (MD) simulation
technique. (The details can be found elsewhere [24, 49]).
A fast timing configuration of the “Ortec” positron lifetime system was used.
“Scionix” modules equipped with two XP 2020Q photomultiplier tubes optically
coupled with cylindrical BaF 2 scintillators (∅ 25.4 mm, 10 mm) operated as the detectors of two different γ -quanta attributed to start (1274.6 keV) and stop (511.0 keV) of
a positron lifetime. A 0.1 MBq
22 Na positron source sealed by kapton foils (12.5 μm
in thickness) was placed between two plates of the same sample (~1.5 mm in thickness). The time resolution of the device was determined to be 230 ps from the prompt
curve of a
60 Co source, at the temperature T = 18 °C and relative humidity RH =
35%.
About a million of elementary annihilation events were collected to evaluate
positron lifetime components τ 1 , τ 2 , τ 3 , and intensities I 1 , I 2 , I 3 from row positron
annihilation lifetime spectra fitted by three components. The mathematical treatment
of PAL spectra was performed with LT 9.0 program [50] without constraints imposed
B. M. Gorelov et al.
structure. The structural formula of the resin can be found elsewhere [27]. The resin
underwent no additional purification procedure before using. The epoxide to the
hardener ratio was kept to be constant at 5:1.
The multiplication of the dipoles may result from breaking amine cross-links
(ACLs) and shortening EMCs.
No efforts to orient MLG-NPs within the nanocomposites have been undertaken
in the present study because the orientation-related anisotropy may hinder to unveil
peculiarities of filler-epoxy interactions. The filler-mass-loadings (C f ) were 0.5, 1,
2, and 5% for both the nanocomposites. As prepared liquid composites of both the
types were mixed manually until homogeneous suspensions were obtained, and their
further polymerization occurred at room temperature during 72 h.
2.2 Experimental Techniques
Dielectric properties were obtained by measuring complex permittivity using the
computer-controlled impedance meter Hioki IM3536 General Purpose LCR Meter.
Details of the measuring technique can be found elsewhere [45]. The procedure of
preparation of samples is described in [46].
An impact of MLGNPs on thermal stability of the epoxy has been determined
by using a programmable thermal desorption technique combined with a massspectroscopic detection (TDMS) via the single-pole mass-analyzer MX 7304A.
Details of the measuring technique can be found elsewhere [47, 48].
The experimental values of the dynamic elastic modules of the epoxy and its
MLG-nanocomposites (namely, the Young’s modulus E, the compression modulus
M, the Lame constants λ and μ, and the Poisson’s ratio ν) have been calculated via
values of longitudinal (V L ) and shear (V S ) wave phase velocities (measured within
the frequency range of 1.5–2.0 MHz) and calculated values of the nanocomposite’s
density ρ by using a procedure described in [48]. The theoretical values of the
modules have been calculated by using the molecular dynamic (MD) simulation
technique. (The details can be found elsewhere [24, 49]).
A fast timing configuration of the “Ortec” positron lifetime system was used.
“Scionix” modules equipped with two XP 2020Q photomultiplier tubes optically
coupled with cylindrical BaF 2 scintillators (∅ 25.4 mm, 10 mm) operated as the detectors of two different γ -quanta attributed to start (1274.6 keV) and stop (511.0 keV) of
a positron lifetime. A 0.1 MBq
22 Na positron source sealed by kapton foils (12.5 μm
in thickness) was placed between two plates of the same sample (~1.5 mm in thickness). The time resolution of the device was determined to be 230 ps from the prompt
curve of a
60 Co source, at the temperature T = 18 °C and relative humidity RH =
35%.
About a million of elementary annihilation events were collected to evaluate
positron lifetime components τ 1 , τ 2 , τ 3 , and intensities I 1 , I 2 , I 3 from row positron
annihilation lifetime spectra fitted by three components. The mathematical treatment
of PAL spectra was performed with LT 9.0 program [50] without constraints imposed