Abstract:
Dielectric monitoring and supporting techniques (differential
Scanning calorimetry, infra-red spectrosoopy, viscometry, dynamic
mechanical thermal analysis and light transmittance) were used to
study the isothermal cure reaction of the CTBN
rubber modified
DGEBA resin/amine hardener blends. The neat system was also
examined for the required knowledge of the matrix properties. The
complexity of the cure kinetics was demonstrated by the use of a
rapid technique for kinetic parameters evaluation.
The utility of the dielectric cure
monitoring is focused at the
observation of evidence o phase separation, gelation and
vitrification. The phase separatlon which the blends underwent
during the cure was detected by the dielectric »monitoring through
a
permittivity increase at the low frequency
response. The onset
of the rapid viscosity increase leading to gelation was also
indicated by the sharp decrease o the dielectric constant atlhigh
frequencies. The frequency dependence of the times reach the
dielectric loss peaks was used to predict successfully the
vitrification
times during the isothermal reactions o the blends.
The in-situ nature o the technique and the basic
understanding o the features appearing in the dielectric signal
during the cure reaction provide the basis for the
use of dielectric
monitoring in the process of composite
materials, manufacture.
