9 Polymeric Composite Films with Controlled Release of Natural Antioxidant Enoxil
157
In spectrum of polymeric films with HEMA, the characteristic vibrations of
ester groups 1100–1300 cm −1 and deformation vibrations of (CH) bonds at 1300–
1500 cm −1 have been detected [16]. The absorption bands at 1079 and 1022 cm −1
corresponded to d(CO) in –O–CH 2 –(gosh) and d(OH), respectively. The characteristic bands of HEMA are (–O–C=O) group vibration mode near 1740 cm −1 , valence
vibration of CH= in (C(CH 3 )=CH 2 ) group at 1640 cm −1 , as well as double band
of d(C–H) in –CH 2 –C vibration at 1457 cm −1 (bending) and 1488 cm −1 (scissoring)
[17].
Samples of 8–16 mg in mass, cut from the produced plate, were closed in
standard Tzero aluminum pans. Cooling and heating rates were 10 ◦ C/min. During
the 1st heating scan, the samples stayed at 100 ◦ C for 5 min (isothermally) and
during the 2nd heating scan at 20 ◦ C for 3 min in order to stabilize the materials.
The DSC curve of first heating (Fig. 9.5) shows smooth heat consumption during the
volatile matter and moisture eliminating with an extremum near 101.5 ◦ C (Table 9.2,
Fig. 9.5). During the first heating, the copolymer Gel/HEMA was post-cured, and
on the next heating run, the exothermic band at 161 ◦ C was marked that can point
on high crystallinity degree of obtained structure. The crystallization and melting
peaks are only observed for polymers that can form crystals. Most likely the main
contribution to the material structure ordering is made by gelatin, since HEMA
is a glass-like but amorphous polymer. While purely amorphous polymers will
only undergo a glass transition, crystalline polymers typically possess amorphous
domains and will also exhibit a glass transition as seen in Fig. 9.5a, b (samples
Gel/Chit/HEMA and Gel/Chit/HEMA/VA, 2nd heat run curves). For these materials
the exothermic band near 299 ◦ C coursed by chitosan presence. The amorphous
portion only undergoes the glass transition, while the crystalline regions only
undergo melting. The melting point for the Gel/HEMA sample was 264 ◦ C followed
by an endotherm, which refers to the thermal destruction of the material. In contrast,
a sample of a similar polymer part composition with the addition of organosilanes
(Gel/HEMA/VA) does not have an ordered structure (Fig. 9.5b). At the same time, it
is possible to select on the curve a section related to the glass transition at T g 83 ◦ C.
The subsequent endotherm probably refers to the thermal destruction of the material.
The exact temperatures at which the polymer chains undergo these transitions
depend on the structure of the polymer. Namely, another effect has the presence of
organosilanes on the ternary composite containing chitosan Gel/Chit/HEMA/VA.
The resulting material has an amorphous (T g ) and a crystalline part (T c ). The high
ordering of the structure is indicated by a narrow intense crystallization peak due
to the presence of chitosan. Subtle changes in polymer structure can result in huge
changes in T g . For the Gel/Chit copolymer, during first heat run, the glass transition
was found at 56 ◦ C. After removal of moisture and post-curing during isothermal
stage, the glass transition temperature shifts to 92 ◦ C, and a narrow exotherm is
retained at 290 ◦ C. The introduction of carbon nanotubes into the material reduces
the crystallinity of the polymer, but the internal architecture of the copolymer in
general is not violated, and only change in the thermal resistance of the material
was noted.
157
In spectrum of polymeric films with HEMA, the characteristic vibrations of
ester groups 1100–1300 cm −1 and deformation vibrations of (CH) bonds at 1300–
1500 cm −1 have been detected [16]. The absorption bands at 1079 and 1022 cm −1
corresponded to d(CO) in –O–CH 2 –(gosh) and d(OH), respectively. The characteristic bands of HEMA are (–O–C=O) group vibration mode near 1740 cm −1 , valence
vibration of CH= in (C(CH 3 )=CH 2 ) group at 1640 cm −1 , as well as double band
of d(C–H) in –CH 2 –C vibration at 1457 cm −1 (bending) and 1488 cm −1 (scissoring)
[17].
Samples of 8–16 mg in mass, cut from the produced plate, were closed in
standard Tzero aluminum pans. Cooling and heating rates were 10 ◦ C/min. During
the 1st heating scan, the samples stayed at 100 ◦ C for 5 min (isothermally) and
during the 2nd heating scan at 20 ◦ C for 3 min in order to stabilize the materials.
The DSC curve of first heating (Fig. 9.5) shows smooth heat consumption during the
volatile matter and moisture eliminating with an extremum near 101.5 ◦ C (Table 9.2,
Fig. 9.5). During the first heating, the copolymer Gel/HEMA was post-cured, and
on the next heating run, the exothermic band at 161 ◦ C was marked that can point
on high crystallinity degree of obtained structure. The crystallization and melting
peaks are only observed for polymers that can form crystals. Most likely the main
contribution to the material structure ordering is made by gelatin, since HEMA
is a glass-like but amorphous polymer. While purely amorphous polymers will
only undergo a glass transition, crystalline polymers typically possess amorphous
domains and will also exhibit a glass transition as seen in Fig. 9.5a, b (samples
Gel/Chit/HEMA and Gel/Chit/HEMA/VA, 2nd heat run curves). For these materials
the exothermic band near 299 ◦ C coursed by chitosan presence. The amorphous
portion only undergoes the glass transition, while the crystalline regions only
undergo melting. The melting point for the Gel/HEMA sample was 264 ◦ C followed
by an endotherm, which refers to the thermal destruction of the material. In contrast,
a sample of a similar polymer part composition with the addition of organosilanes
(Gel/HEMA/VA) does not have an ordered structure (Fig. 9.5b). At the same time, it
is possible to select on the curve a section related to the glass transition at T g 83 ◦ C.
The subsequent endotherm probably refers to the thermal destruction of the material.
The exact temperatures at which the polymer chains undergo these transitions
depend on the structure of the polymer. Namely, another effect has the presence of
organosilanes on the ternary composite containing chitosan Gel/Chit/HEMA/VA.
The resulting material has an amorphous (T g ) and a crystalline part (T c ). The high
ordering of the structure is indicated by a narrow intense crystallization peak due
to the presence of chitosan. Subtle changes in polymer structure can result in huge
changes in T g . For the Gel/Chit copolymer, during first heat run, the glass transition
was found at 56 ◦ C. After removal of moisture and post-curing during isothermal
stage, the glass transition temperature shifts to 92 ◦ C, and a narrow exotherm is
retained at 290 ◦ C. The introduction of carbon nanotubes into the material reduces
the crystallinity of the polymer, but the internal architecture of the copolymer in
general is not violated, and only change in the thermal resistance of the material
was noted.