Thermal study of naphthylammonium- and naphthylazonaphthylammonium-montmorillonite XRD and DTA

摘要

The blue organo-clay color pigment (OCCP) naphthylazonaphthylammonium-montmorillonite was synthesized from the white naphthylammonium-montmorillonite by treating with NaNO2, the azo colorant being located in the interlayer space. The following effects on the basal spacing of naphthylazonaphthylammonium-and naphthylammonium-clay were investigated: (1) the amount of naphthylammonium loading the clay, (2) the amount of NaNO2 used for the staining, (3) aging of the preparation suspension and (4) thermal treatment. Samples were heated at 120, 180, 240, 300 and 360 degrees C and diffracted by X-ray. During aging, some of the dye decomposed. Samples, after one day aging, were investigated by DTA. During the dehydration stage both organo-clays gradually decomposed, the naphthylammonium-clay at 120 degrees C and the OCCP at 180 degrees C. That fraction of organic matter, which did not escape, was air-oxidized at above 200 degrees C and charcoal was obtained. The appearance and size of the DTA exothermic peaks depended on the amount of organic matter, which did not escape and this depended on the total amount of organic matter in the DTA cell. DTA proved that naphthylammonium reacted with NaNO2 to form OCCP.