Abstract:
The
study described in this thesis examines how modification
with different
thermoplastics affects the structure and
properties of
a
tetrafunctional
epoxy re5ín_
Polyetherimide (PEI) is found to give the best improvement in
fracture
properties without loss in
Youngs Modulus and the
PEI/epoxy
system is used as the basis for further
study.
The influences of PEI
concentration, initial cure
temperature,
test
temperature and the presence of a second
thermoplastic additive,
are
investigated. The information
provided gives insight into the
likely mechanisms of
toughening in tetrafunctional
epoxy/thermoplastic blends.
Flory-Huggins Lattice Theory is used to describe
miscibility
behaviour for a number of
curing thermoplastic/epoxy blends and the
predictions compared with the actual
morphologies observed.
Further,
the
sensitivity of the expected miscibility behaviour to fluctuations
in
Flory Huggins interaction parameter
X12 and number-average
molecular
weight Mn of the
thermoplastic, is considered. Dynamic
mechanical
analysis is used to monitor the
changing viscoelastic
properties of curing thermoplastic/epoxy blends, allowing
investigation of the way different thermoplastics influence the state
transformation
profile of a curing epoxy resin.