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Measuring the Extent of Exfoliation in Polymer/Clay Nanocompsites Using Real-Time Process Monitoring Methods



Anthony J. Bur, T Y. Lee, S C. Roth, P R. Start


Polymer/Clay nanocomposites were compounded using a twin screw extruder that was instrumented with multiple sensors. The sensors were situated in a slit die chamber that was attached to the exit of the extruder and yielded data about dielectric, optical, temperature and pressure properties of the extrudate. Data from these sensors were correlated with off-line transmission electron microscopy observations in order to determine the relationship between on-line macroscopic measurements and off-line microscopy. Dielectric measurements, carried out at processing temperatures over a range of frequencies on nylon 11, nylon 12, and nylon 6 and compounded with organo modified montmorillonite clays, displayed large Maxwell-Wagner (MW) relaxations.The characteristic frequency of the MW relaxation, which reflects an RC time constant associated with the conduction of ions and the polarization of the resin/clay interface, was observed to be a function of the extent of clay exfoliation. Optical transmission measurements showed that transmission increased with increasing extent of exfoliation because light scattering due to aggregate clay particles is reduced as the particles exfoliate nanosize silicate flakes that are too small to scatter light. Generalized exfoliation scales, based on the MW relaxation time and its relationship to interfacial polarization, and based on optical transmission measurements, are developed.
Nano Letters


dielectric spectroscopy, exfoliation, light transmission, montmorillonite clay, nylon, polymer nanocomposites, process monitoring


Bur, A. , Lee, T. , Roth, S. and Start, P. (2008), Measuring the Extent of Exfoliation in Polymer/Clay Nanocompsites Using Real-Time Process Monitoring Methods, Nano Letters (Accessed April 14, 2024)
Created October 16, 2008