Abstract:
The
aim of the present work was to investigate the evolution of thermal and
mechanical properties during the polymerisation of a thermosetting resin that is typical
those used as the matrix
in
advanced composites. The
mechanism of the cure reaction
was studied using
differential
scanning calorimetry
(DSC) in both dynamic (thermal
scanning) and
isothermal
modes, and procedures
for
correlating the two types of
calorimetric
data were
developed. The
model
finally
chosen encapsulates the diffusion-
controlled mechanism of reaction by
establishing a one-to-one relationship between the
degree of cure and the glass transition temperature, which
is
assumed to be
a structural
parameter during the polymerisation. A detailed
experimental investigation
of specific
heat
capacity, thermal
conductivity, secondary transformations (gelation
and
vitrification), thermal and chemical volume changes and stress relaxation moduli was
carried out to establish a suitable
database for the resin.
Where
possible, a closed
analytical model was employed; alternatively, an interpolation
procedure was developed
evaluate the changes in
a selected property
during
a more complex
temperature
profile.
Experimental
equipment was
developed to perform shrinkage measurements on
the neat resin system; the results obtained were
later
compared with experimental
data
from
standard liquid dilatometry tests.
A
simulation of the curing of a bi-material
cantilever beam is
presented as a test case
highlight the influence
of property changes on the final
curvature. Sample curvature
during the experiment was recorded using a
digital
camera and then analysed using
graphical software.
The
correlation
between the observed values of curvature and the
results of a
finite
element based simulation was used to validate the kinetics model and
property modelling
for the chosen thermosetting resin.
