|
The effect of the epoxidized nature rubber(ENR) on the curing
and phase separation behaviors of the epoxy/dicyandiamide resin
system was studided with the differential scanning calorimetry
(DSC),scannung electron microscopy(SEM), Fourier transform
spectroscopy(FTIR), and lap shear test. The presence of ENR
resulted in changesin initial transition rate, Tg, activation
energy, reaction heat, reaction rate , and reaction order of the
epoxy system. Two ENR''s responded differently because of
difference in structure, the reactivity with the matrix system,
and the flexibility. The rubber phase was obtained from the ENR
modified system and whose size, volume fraction, and
distribution changed with respect to the curing temperaure, and
the type /amount of the ENR used. The addition of rubbery ENR
resulted in the decrease of the lap shear strength. Regardless
of the various curing mechanisms involved, a simple Kamal model
could describe the curing kinetics with a good accuracy for all
systems studied.
|