Studies on epoxy/calcium carbonate nanocomposites

The article describes the preparation of epoxy‐calcium carbonate nanocomposites using diaminodiphenyl sulfone (DDS) as a curing agent. The curing behavior of diglycidyl ether of bisphenol‐A (DGEBA) (1 mol) in the presence of varying amounts of nanocalcium carbonate was investigated by differential scanning calorimetry (DSC) using stoichiometric amounts of diaminodiphenyl sulphone (0.5 mol) as curing agent. The amount of calcium carbonate (∼ 44 nm) was varied from 2% to 10% (w/w). In the DSC scans of these samples, a broad exothermic transition due to curing was observed in the temperature range of 110–335°C. As expected, heat of curing decreased with increasing amount of nanocalcium carbonate; however it did not affect the curing characteristics, thereby indicating that the filler did not hinder the curing reaction. Thermal stability of DGEBA in the presence of varying amounts of nano‐CaCO 3 after isothermal curing [(i.e., by heating in an air oven at 80°C (1 h), 100°C (1 h), 120°C (1.5 h), and 180°C (4 h)] was evaluated by thermogravimetry. All the samples were stable upto 350°C, and char yield at 800°C increased with increasing amount of nanocalcium carbonate. Rectangular bars were prepared by mixing DGEBA, DDS, and varying amounts of CaCO 3 using silicone mold. The nanocomposites were characterized by X‐ray, scanning electron microscopy (morphological characterization), and dynamic mechanical analysis.