Frequency dependent electromagnetic sensing provides a sensitive, convenient, automated means for monitoring the infiltration, polymerization, and degradation processes in polymeric systems. In situ FDEMS sensing was used to monitor both Hercules Corporation's 3501-6 epoxy resin system and the Minnesota Mining and Manufacturing Corporation's PR500 epoxy resin system during the Resin Transfer Molding (RTM) infiltration and cure process. FDEMS sensing observed the resin position, viscosity, degree of cure, and the buildup in macroscopic properties such as modulus. Degradation of Nylon-11 in various accelerated aging and operational environments was also monitored by in situ FDEMS sensing. By monitoring the entire polymerization and degradation process, in situ FDEMS sensing is able to provide important real time information about the current physical state of various polymeric materials during processing and during use in the tidal environment.
Currently, the chemical industry is limited in their procedural and analytical capabilities of large scale batch reactor processing. Batch reactors are driven by a time and temperature criteria. This criterion does not take into account nor adjust to the small cumulative differences in the timing of the reactor process, variations in ingredients, operator handling, and differences from one reactor environment to another. Each one of these uncontrollable factors affects the reaction. Therefore, procedures based on repetitive time and temperature criteria produce a final product with variable consistency and quality. Furthermore, analytical characterizations are limited to laboratory measurements of samples removed from the reactor and then analyzed in a laboratory setting. Our goal is to replace the time/temperature criteria and sample/analyze technique with an in-situ online sensor driven Frequency Dependent Electromagnetic Sensing (FDEMS) system. This would ensure final product consistency and quality.
The Primary goal is to monitor the degradation of polymers in-situ during use, using techniques which allow prediction of the lifespan of the polymer while the polymer is in the field environment. Experiments are conducted which correlate in situ measurements of the changing mobility of molecules and ions to macroscopic mechanical properties of polymers. Frequency Dependent electromagnetic sensing is used to record dielectric measurements at several different frequencies over a period of time.
Using the Cray Supercomputer at the National Institute of Standards and Technology (NIST), we are attempting to model the movement of polymers in the molten state, during the transition to the solid glass state and during aging once in the glassy state. We are also looking into the effects of size confinement and quenching rate to determine their effects on the glass transition temperature and the dynamical behavior of macromolecules confined to small pores.
Our research examines the accelerated aging of polymer materials with the aid of various instruments. The first part focuses on composite systems used in the oil industry by examining the bulk property of these polymers. Both nylon-11 (Rilsan) and poly(vinylidene fluoride) (PVDF) have played an important role on the oil platforms in the North Sea. The kinetic rate of degradation of nylon-11 is seen through the study of the temperature and pH dependence at various percentages of water. This is important in determining the amount of degradation of the nylon-11 at varying times and position in the pipe.
PVDF
provides a crucial high temperature inner fluid barrier in the oil pipe, and
its stability is similarly monitored using FDEMS sensing and by testing its
microscopic and macroscopic properties during immersion in various harsh
chemical environments.
PPS
(Polyphenylene sulfide) is another strong lightweight polymer that has the
potential to replace the steel coil that is currently used to reinforce the
pipe. Its resistance to significant degradation in simulated seawater at both
90 C and 120 C at this stage of study offers an optimistic outlook for its use.
The
last part of this work examines the cure and degradation processes of a
vinylester coating, Chemflake, is used in protecting steel tanks from acidic
conditions. Using in situ frequency dependent electromagnetic sensing
(FDEMS), the ionic mobility and the behavior of pendant polar groups off the
polymeric backbone are studied qualitatively. Hardness measurements along with
degree of cure correlate well with FDEMS sensing data, which monitor the
resistance of this coating to a highly acidic environment at elevated
temperatures.