Effect of Clay Surface Treatment

Clay surface treatment can influence its reaction with the catalyst and in turn determine the stabihty of polymerization active site on the clay surface. As mentioned earher, there are two main types of clay surface treatments thermal and chemical. Thermal treatment at high temperatures may result in loss of sweUabil-ity [96] and reduced efficiency for in-situ polymerization appHcations. 

The type of alkylaluminum and the procedure of addition have a great influence on the success of in-situ polymerization. Lee et al. [52] used MMAO to treat Cloisite 25A for catalyst supporting, obtaining a highly active catalyst system, while Maneshi et al. [62] showed that using TMA for surface treatment of Cloisite 25A before catalyst supporting did not result in any polymerization activity. Lee et al. [52] attributed their positive results to reactions between quaternary ammonium 

Using the same technique applied by Maneshi et al. [62], Ushakova et al. [106] showed that treating Na MMT with TIBA led to a catalyst that had a higher propylene polymerization activity than when the same clay was treated with TMA. 

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