Synthesis and Characterization of Alkyd Resin Microcapsules - Natural Polymers, Biopolymers, Biomaterials, and Their Composites, Blends, and IPNs - page 233

infrared spectroscopy
In order to ascertain UF encapsulation of resin, spectra of original alkyd resin is com-
pared with the spectra of soxhlet extracted resin. The purpose of Soxhlet apparatus is
to extract core material from the outer membrane. The core material collected after
soxhlet extraction was mixed with Potassium Bromide and palette was prepared for
recording spectra using fourier transform infra red spectroscopy (FTIR).
analysis of shell morphology
Scanning Electron Microscopy was performed to analyze surface morphology and
shell wall thickness of the capsule. A dried microcapsule was placed on a conduc-
tive carbon tape attached to a mounting piece for imaging. Few microcapsules were
ruptured with a razor blade to confirm the presence of alkyd resin inside the UF shell.
thermal analysis of microcapsules
Microcapsules were analyzed using thermo gravimetric analyzer (SDT Q600V8.0, Ta
instrument) in nitrogen environment with a sample weight of about 4.6170mg. Heat-
ing rate was maintained at 10°C/min in the temperature range of 30-800°C. Simi-
larly samples were also analyzed by using differential scanning calorimeter(DSC Q10
V9.0, TA instruments) in oxygen environment with sample weight of about 6.2mg at
heating rate of 10°C/min, between 30 and 400°C.
results aNd disCussioN
Urea-formaldehyde capsules are formed by the reaction of urea and formaldehyde
to obtain methylol ureas, which condenses under acidic conditions to form the shell
Material. Alkyd Resin encapsulation takes place simultaneously during formation of
cross-linked urea-formaldehyde polymer. When the pH is changed to acidic and heat-
ed to 55°C, urea and formaldehyde reacts to from poly (urea-formaldehyde).
Ftir analysis
The FTIR spectra of original alkyd resin and soxhlet extracted resin are shown in
Figure 2 which shows the characteristic peaks of ester stretching (COOR) at 1729.49
cm -1 , unsaturated fatty acid at 1266.23 cm -1 and aromatic CH deformation at 730cm -1
closely matches thus establishing that alkyd resin has been successfully encapsulated
within urea-formaldehyde shell.
thermal analysis
Thermal analyses of microcapsules were carried out to prove encapsulation of alkyd
resin inside UF Shell. The TGA of microcapsule is done and the curve is shown in
Figure 3. The first endothermic peak at 229.2°C corresponds to UF decomposition
temperature (Suryanarayanaa et al., 2008) and the endothermic peak at 350°C cor-
responds to the start of alkyd resin decomposition temperature which ends at 450.5°C.
These results establish that microcapsules contain alkyd resin as core and UF resin as
the shell. The weight loss of the sample was found to be 4.5 mg (98.11%)