Improving the thermal stability and dielectric properties of epoxy/phenolic resin type (novolac) composites by incorporating carbon nanofibers (CNFs)

This study aims to enhance the thermal stability and dielectric properties of an epoxy/phenolic resin-type novolac blend by incorporating carbon nanofibers (CNFs). The EP/novolac-CNF composite was created by dispersing a 10% weight fraction of CNFs into the EP/novolac blend. Various analyses were conducted to assess the improvements brought by the addition of CNFs. Differential Thermal Analysis (DTA) and Dielectric Measurements (DM) were employed to determine the Tg values. Thermogravimetric Analysis (TG) and Differential Thermogravimetric Analysis (DTG) were used to evaluate the thermal stability. Results indicated that the inclusion of carbon nanofibers enhanced the thermal stability of the composite, as evidenced by the increased char yield at temperatures exceeding 700 oC, reaching 27.08% compared to 8.4% for the EP/novolac blend. Dielectric measurements were conducted across a frequency range of 102 -107 Hz and a temperature range of 293-463 K. The results revealed a wide dielectric dispersion in all samples, indicating the presence of Debye relaxation and a broad distribution of relaxation times. Eyring’s relaxation rate equation was applied to determine the thermodynamic parameters, such as the Gibbs free energy of activation (\Delta G) and entropy (\Delta S). The results indicated strong intermolecular interactions in all tested samples. The incorporation of carbon nanofibers into the EP/novolac blend led to improvements in thermal stability and dielectric properties. The analysis of various parameters suggests enhanced performance and potential applications of the EP/novolac-CNF composite in relevant fields.