Preparation, thermal stability and decomposition routes of clay/Triton-X100 composites

The adsorption isotherms for the octylphenol ethoxylate, TX100, onto a rang e of bentonites and a saponite have been determined and the resulting therm al stability of composites has been studied. In general TX100 exhibited a h igh affinity for the different clay surfaces although the maximum amount ad sorbed varied with both clay type, layer charge density and resident exchan ge cation. XRD and variable temperature XRD showed that TX100 was adsorbed into the interlamellar region, and that the thermal stability of the clay/T X100 composite was dependent upon the exchangeable cation present. For mono valent cation exchanged clays (M+-clay/TX100) the TX100 decomposed between 220 and 300 degrees C, and the d(001) spacing decreased from 15.2 to 9.6 An gstrom. In contrast, divalent cation exchanged clays imparted a greater the rmal stability to the complex (M2+-clay/TX100) owing to coordination of ads orbed TX100 to the exchange cation, wherein weakly coordinated TX100 was st able to 270 degrees C and strongly coordinated TX100 was held to temperatur es in excess of 300 degrees C. FTIR analysis of the gases evolved evolved d uring thermogravimetry confirmed that the octylphenol unit was desorbed fro m M2+-clay at temperatures below 400 degrees C and that portions of the eth oxylate chain were held to 500 degrees C.