Kinetics of cure for a coating system including DGEBA (n = 0)/1,8-NDA and barium carbonate

The increasing demand for low-cost and high performance coatings has promoted the development of chip epoxy-based coatings using inert fillers. Attention has been paid here on employing mixtures of DGEBA with barium carbonate as novel ceramic-based filler to produce a coating using 1,8-naphthalene diamine (1,8-NDA) as the crosslinking agent. A substantial increase in the T_g, from 85 to 100 °C, is observed for the optimum composition. The 1,8-NDA-cure of the epoxy composites showed an autocatalytic mechanism. At a specific conversion range the cure reaction of the composites will be controlled by a diffusion-control cure reaction rather than by Kamal autocatalytic model. Model-free isoconversional method is utilized to construct apparent activation energy dependence on conversion plot. The effect of diffusion control is described by an approach proposed by Chern and Poehlein. Greater diffusion control is observed as the cure temperature decreased.