Enthalpy relaxation of reactive graphitic nanofibers reinforced epoxy

The enthalpy relaxation of an epoxy resin modified by three different concentrations of reactive- Graphitic Nanofibers (r-GNFs) has been investigated by standard and modulated differential scanning calorimetry (DSC). From DSC scan at 10 C/min following cooling at various rates through the transition region, the apparent activation energy, Dh*, was evaluated. The non-linearity parameter, v, was analyzed by the peak shift method for samples annealed at temperature Tg –20 C for different period of time (up to 167 h). The non-exponentiality parameter, b, was determined based on the inflectional slope of the complex heat capacity. The experimental results showed that the incorporation of r-GNFs into epoxy network causes greater non-linearity, higher apparent activation energy, and broader relaxation time distribution than the neat epoxy resin. These values were optimum for epoxy resin with 0.3 wt% of r-GNFs