RP116 -
In-Situ Cure Monitoring of Isocyanate Adhesives Using Microdielectric
Analysis, Michael P. Wolcott and Timothy G. Rials
ABSTRACT
Recent advances
in microelectronics have produced small electrodes that can
be used for remote dielectric measurements. These miniature
sensors are small enough to be embedded in a composite panel
during manufacture with little disturbance to the manufacturing
process. Small particleboard panels (5 by 4.5 by 0.25 in.)
were manufactured with 6 percent polymeric diphenylmethane
diisocyanate resin in a laboratory hot-press. A dielectric
sensor was embedded in the core of each panel to measure both
temperature and dielectric responses. The curing behavior of
the particleboard furnish was also examined using dielectric
analysis in a controlled oven and differential scanning calorimetry.
Close agreement was found between the curing response detected
by both these techniques. In addition, the curing response
of particleboard furnish in a controlled oven was remarkably
similar to that seen in situ during particleboard manufacture
using four different platen temperatures. The contribution
of moisture changes during pressing to the dielectric signal
was evaluated. Finally, two different sensor designs were evaluated
on a limited basis.
RP119 -
The Viscosity and Ion Conductivity of Polydimethylsiloxane
Systems: 1-Chain length and Ion Size Effects; 2-Ion Concentration
Effects , School of Chemical Engineering, Georgia Institute
of Technology, J.E.Companik and S.A.Bidstrup
ABSTRACT
The zero-shear-rate
viscosity and ion conductivity of a homologous series of polydimethylsiloxane
(PDMS) oils and six homologous series of PDMS salts of various
univalent cations (sodium, potassium, tetramethylammonium,
tetraethylammonium, tetrapropylammonium and tetrabutylammonium)
were measured over the temperature range -45C to 80C. Free
volume and Arrhenuis type viscosity and ion conductivity models
were successfully applied to these data. The effects of polymer
chain length and ion size on the values of the best-fit model
parameters were explored.
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RP093 -
Curing Characteristics of a Zinc-Catalyzed Cynate Ester Resin
System, Syracuse University, Yong Deng and George Martin
ABSTRACT
Cyanate-based
resins have been the focus of a number of recent publications.
Their attractive features include excellent adhesion characteristics,
good mechanical properties, low dielectric constants and glass
transition temperatures in the range of 260C. Thus, the resins
are considered especially suitable for composite and electronic
applications.
The major reaction
pathway for the cyanate resins is the cyclotrimerization of
cyanate groups to form triazines. Unlike many epoxy resins,
such as epoxy-amines, the curing of cyanate resins has been
found to become diffusion-controlled even in the pre-gel stage.
As the diffusion control may also affect the structural properties,
understanding the diffusion-related curing characterisitcs
is important for elucidating the structure-property relationship
of the cyanate resins.
The objective
of the present work was to examine the dielectric behavior
and molecular size distribution of a zinc-catalyzed cyanate
ester resin in order to estimate the average diffusivity in
the cure system, and to develop a quantitative model to predict
the diffusion-controlled cure kinetics of cyanate resins.
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RP057 -
Cure Studies of Interpenetrating Networks by Microdielectrometry;
Naval Research Laboratory, B.S.Holmes and C.A.Trask
ABSTRACT
Microdielectrometry
has been use to follow the cure kinetics of interpenetrating
polymer networks (IPNs). The rate of formation of a polyurethane-poly(n-butyl
acrylate) IPN has been characterized at three temperatures.
The dielectric data indicate that the relative homonetwork
formation rates dominate the resultant material properties.
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RP048 -
Filled Acrylic Systems: Cure Monitoring using Microdielectrometry,
Ceramics Process Systems Corporation,, K.Venkataswamy and
R.Waack
ABSTRACT
Microdielectrometry
was employed to monitor cure of a polymer binder precursor
based on acrylic monomer systems. Polymeric binders, in general,
are crucial in forming applications of ceramics such as tape
casting to manufacture ceramic substrates or packages. In this
process technology, the principles of reinforcing polymer systems
with powders are applied in processing the fillers themselves.
A very novel method is investigated; high solids loading of
ceramic powders was dispersed in acrylic monomer systems, which
can be cured by free radical mechanism. The effects of solids
loading, initiator level, and cure temperature on the cure
rate are examined by Microdielectrometry in such highly filled
systems.
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RP096 -
A Microdielectric Analysis of Moisture Diffusion in Thin
Epoxy/Amine films of Varying Cure State and Mix Ratio, Micromet
Instruments, Inc. David Day, David Shepard, and Kelly Craven
ABSTRACT
This work shows
that dielectric sensors can be used to monitor moisture diffusion
in polymer materials ranging from composites to thin films.
When the technique is used with thin films, diffusion coefficients
and degree of moisture uptake can be determined very quickly.
This paper describes preliminary moisture diffusion analysis
carried out in thin epoxy films as a function of ultimate cure
state and mix ratio of epoxide to amine components.
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