Differential scanning calorimetry (DSC)
DSC measurements were carried out in Differential scanning
calorimetry (DSC) Q-1000 model supplied by TA Instruments,
USA. The resins of 6 mg is placed on high pressure aluminum
crucibles. The samples were heated from 30 1C to 200 1C in an
inert atmosphere of nitrogen maintained at 50 ml/min flow
rate, with an identical empty crucible used as a reference in
the measurement process. The heating rates employed were 5,
10 and 15 1C/min. The peak curing temperature (Tp) estimated
at different heating rate (i.e. 5, 10 and 15 1C/min). Ea is
calculated from the slope of a plot of the natural logarithm
of heating rate versus the reciprocal of the corresponding type
[in degree Kelvin (K)] using Kissinger's equation [19] Eq. (2).
lnðβ=T2p
Þ ¼ −Ea=RTp þ lnðAR=EaÞ ð2Þ
where, β is the heating rate, Tp is the peak curing temperature,
R is the gas constant and A is the pre-exponential factor. The
value of Ea and A were determined from the graph plotted
between ½−lnðβ=T2p
Þ and ½100=Tp.
(b) Fourier transforms infrared spectroscopy
The pre-cured resin and samples were mixed with KBr and
made into pellets to determine the bond formation using
Fourier transform infrared spectroscopy (FTIR). The FTIR
transmittance spectra were obtained with Perkin-Elmer spectrum
100 in the spectral range of 400–4000 cm−1, with a
resolution of 2 cm−1 and 50 scans.
(c) Scanning electron microscopy
The morphology of the prepared samples were examined
using Field Emission Scanning Electron Microscopy (FESEM)
system (JEOL JSM 840A-Oxford ISIS 300 microscope). The
samples were carbon coated in order to provide good conductivity
of the electron beam. Operating conditions were