Abstract
The possibility of reaction between acetic anhydride and ground halloysite was studied; 100g of halloysite was ground with 300ml of acetic anhydride in a Hyswing ball mill. The reaction products were examined by the X-ray diffraction techniqe, DTA and infrared spectroscopy.
The DTA curves and the infrared spectra of the reaction products indicated that the reaction between acetic anhydride and ground powder of halloysite did occur, whereas, the same reaction did not occur between the original halloysite and acetic anhydride at a room temperature for 24 hours with frequent agitation. The strong absorptions of carboxyl group (COO-) due to it's antisymmetrical and symmetrical vibrations were observed at 1580cm-1 and 1420 cm-1, respectively.
It is probable that many reactive OH groups were exposed on the surface of halloysite crystals by grinding and then acetic anhydride reacted with these OH groups. The formation of ionic bonding between the carboxylate groups and the aluminium ions (Al+), which were exposed on the surface of halloysite cristals by grinding, was suggested from the results of infrared spectra on the ground products.
