[Implication of structure for nano clays used in thermalsetting PU/PLS composite]

Clays such as kaolinite and montmorillonite, are commonly used as an additive to modify the thermal properties of polymer. In the present work, the morphology, composition, shape and structure of montmorillonite and kaolinite were characterized and compared by various advanced techniques. The TEM/EDX data showed that the kaolinite has a larger particle size and a lower Si/Al ratio than montmorillonite. These clays were stacked by platelets. The TGA results revealed that montmorillonite loses significant weight (around 7%) from 60 to 90 degrees C due to the dehydration of absorbed water, however, kaolinite almost doesn't lose weight in this temperature range. Kaolinites loses its weight because of the loss of its structural OH groups at a lower temperature (around 510 degrees C) than montmorillonite (670 degrees C). The PAS-FTIR spectra showed that montmorillnite has a strong absorbance of hydroxyl group in hydrogen bond region at room temperature, which presents a strong ability to adsorb water on its surface. The results of varied infrared temperature and TGA showed that their structural OH group is very stable from 100 to 500 degrees C, and it is possible to form thermosetting PU/PLS composite by reaction with the isocynate group of polyurethane prepolymer.