Thermal degradation of commercially available organoclays studied by TGA-FTIR

Thermogravimetry coupled to Fourier transform infrared spectroscopy (TGA/FTIR) has been used to study the thermal decomposition products evolved during the degradation of several commercially available organoclays (Cloisites (TM) Na+, 10A, 15A, 20A, 25A, 93A and 30B). It was found that the decomposition pattern of the organoclays was different for each sample: Cloisite (TM) 10A shows three well-defined degradation stages, Cloisite (TM) 30B only two stages and the Cloisite (TM) 93A only one weight loss; Cloisites (TM) 15A, 20A and 25A exhibited a more complex behavior showing one main stage and a shoulder. It was also observed that the onset of the decomposition was different for each type of organoclay, being Cloisite (TM) 10A the lowest (160 degrees C) and Cloisite (TM) 93A the highest (212 degrees C). FTIR analysis of the evolved products from their non-oxidative thermal degradation showed the release of water, aldehydes, carboxylic acids, aliphatic compounds and, in some cases, aromatic compounds and CO,. It is suggested that the degradation of both tallow residue and unexchanged surfactant explain the presence of some products evolved during degradation of organoclays. (C) 2007 Elsevier B.V. All rights reserved.