Comparative study of different polymerically-modified clays on curing reaction and thermal properties of epoxy resin

polymerically-modified clays including polystyrene-co-methyl acrylate modified clay (PSMA-clay) and polystyrene-co-acrylic acid modified clay (PSAA-clay), which contain either ester groups or carboxylic acid groups, were prepared by cation exchange and used to prepare diglycidyl ether of bisphenol A (DGEBA)/clay composites. The curing reaction of DGEBA/clay composites was investigated using DSC and FT-IR. The morphology and thermal properties of DGEBA/clay composites were characterized using XRD, TEM, TGA and DSC. DSC and FT-IR analyses demonstrated that there is a reaction between epoxy groups and carboxylic acid groups besides the curing reactions between epoxy groups and the curing agent, 4,4′-diaminodiphenylmethane (DDM) for DGEBA/PSAA-clay composites. XRD and TEM results indicated that the reaction between epoxy groups and carboxylic acid groups in the inter-gallery of PSAA-clay facilitated the clay dispersion in the epoxy matrix. Improved thermal properties due to the addition of reactive clay were also achieved for DGEBA/PSAA-clay composites.