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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