RP088 -
Investigation into the Use of Dielectric Measurements for
the In-Process Monitoring of Batch Resin Polymerization Process,
University of Maryland, Timothy Crowley and David D. Shepard
ABSTRACT
This paper investigates
the use of dielectrometry as an in-process technique for monitoring
and controlling polymerization processes in batch reactors.
Dielectrometry involves measureing the change in electrical
resistivity (also referred to as Ion Viscosity) to monitor
changes in the physical properties, such as viscosity, of the
polymer.
In this paper,
a dielectric sensor was inserted into a laboratory scale batch
reactor and the Ion viscosity monitored during the free-radical
polymerization of methyl methacrylate. In our experiments with
AIBN initiator, good reproducibility was observed between the
fractional monomer Ion Viscosity data. When the initiator concentration
was changed, the relationship between the Ion Viscosity and
fractional monomer conversion shifted.
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RP063 -
The Use of Dielectric Measurements to Determine Blend Time
for Organic Polymer Solutions in Stirred Tanks; Rohm & Haas
Company, Carl Shervin, Joseph Studeny, and Raymond Romaszewski
ABSTRACT
When scaling
up mixing applications, it is often important to measure blend
time. In our application, we need to measure blend time in
nonaqueous solutions of organic polymers in pilot-scale and
plant-scale tanks. Techniques employing visual observations
can be used in small-scale glass or Plexiglas tanks, but these
methods are not applicable to large-scale operations.Another
standard technique is to measure conductivity of a tracer material.
This method is particularly useful for aqueous systems, but
did not provide an adequate response for our system.
A new technique
that we've established involves the measurement of the dielectric
loss of a tracer material added to an acrylic polymer solution
in mineral oil. We have demonstrated that the addition of N,N-dimethylformamide
(DMF) results in mixing curves that give blend times equivalent
to those measured by visual methods.
Our preliminary
studies were performed in a two-liter vessel over a temperature
range of 30-120çC. The magnitude of the dielectric loss measurement
is shown to be dependent on the scanning frequency of the measurement
and the temperature of the polymer solution. The variation
over a small temperature range is slight and will not interfere
with the measurements.
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RP104 -
In-Situ Characterization of Epoxy Polymerization Reactions
by Microdielectric Analysis., The Glidden Company, C.M.Neag,
A.Rohn and D.Bode
ABSTRACT
Dielectric Analysis
(DEA) techniques represent a group of convenient non-destructive
tests that can be used to relate molecular motions observed
in an electrical field to a variety of polymeric properties.
Nearly all the published work in dielectric analysis has focused
on solid materials or monitoring the crosslinking process in
thermoset materials, especially epoxies. This work focuses
on monitoring batch polymerization processes in-situ. The principle
goals of this research center on correlating changes in the
dielectric characteristics of a polymerizing epoxy polymer
with changes in temperaturea and typically measured properties
like viscosity, molecular weight and oxirane level.
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