RP103 -
Simultaneous Dielectrometry and Rheology of Model Epoxy
Resins, National Research Council of Canada, A.Ajji, P.Sammut,
M.M.Dumoulin; IBM Canada, E.Bellefleur and L.Boutin
ABSTRACT
To minimize
flow problems during transfer molding of epoxy resins, it
is important to understand the rheology of these materials
and how it is affected by the chemical reaction. In fact,
during the injection cycle, the epoxy resin crosslinks as
a function of time and temperature, which increases its viscisity
up to infinity (no flow at the gel point). As rheological
measurements are costly and tedious for these resins, use
of alternative techniques is desirable. Use of dielectric
techniques is among the possibilities with the advantage
of its ability to be implemented on the production line.
However, this technique does not measure directly the flow
properties of the resins. Hence, development of correlations
between the dielectric and flow properties of these resins
is of great interest. This paper verifies that linear correlations
can be established between the rheological and dielectric
properties for unreacted epoxy resins. For reacted resins,
molecular weight changes must be taken into account.
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RP114 -Application
of Dielectric and Thermal Analysis to the Curing of Epoxy
Resins, Toshiba Corporation, T.Nakano, S.Makishima, Y.Inoue,
K.Goto
ABSTRACT
Upon studying
the application of dielectric analysis (DEA) to techniques
for non-destructive on-line measuring of the curing process
of epoxy casting resin in molds, it was found that the ionic
conduction portion derived from dielectric loss factor was
closely correlated to glass transition temperature and resin
viscosity. A new study was undertaken using DEA, differential
scanning calorimetry (DSC), dynamic mechanical analysis (DMA)
and curing volume shrinkage measurement to investigate in
more detail the relation between the electrical conductivity
of resins and the degree of cure during the curing process.
A relation was quantitatively determined between the equivalent
resistivity derived from dielectric loss factor and the degree
of cure, viscoelasticity and volume shrinkage.
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RP117 -
Modeling Conductivity and Viscosity Changes During Epoxy
Using DEA, DMA, DSC, Georgia Institute of Technology, Joycelyn
Simpson and Sue Ann Bidstrup
ABSTRACT
Viscosity
and ionic conductivity are macroscopic polymer properties
that characterize polymer segment mobility and ion mobility,
respectively. Numerous studies have demonstrated that viscosity
and ionic conductivity are correlated prior to gelation.
However, few studies have endeavored to gain a fundamental
understanding or quantitative relationship between these
properties. An expression relating viscosity and ionic conductivity
could potentially be quite useful for cure monitoring and
control of polymer processes since ionic conductivity can
be conveniently measured in-situ using microdielectric sensors.
In order to formulate a structure-dielectric property relationship,
this research combines DSC, DMA, and DEA analysis of the
isothermal polymerization of a digycidyl ether of bisphenol
A epoxy resin with a tetrafunctional amine, diamino-diphenyl
sulfone.
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RP041 -
Dielectric Cure Monitoring During Composite Lamination;
IBM Corporation, Jeffery Gotro
ABSTRACT
Oscillatory
parallel plate rheometry is commonly used to measure the
viscosity of neat resins during curing. The objective of
this work was to use a dielectric sensor embedded in an epoxy/glass
cloth prepreg layup to infer the viscosity profile during
lamination. This method allowed qualitative characterization
of the viscosity profile during lamination at different heating
rates.
Correlations
between the dielectric loss factor and the complex viscosity
were established using simultaneous viscosity and dielectric
measurements. Viscosity measurements during composite lamination
would be virtually impossible. The dielectric method is simple
and relatively inexpensive compared to the cost of most rheometers.
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