Polymer Bulletin, Vol.76, No.7, 3785-3801, 2019
Cyclotriphosphazene nanofiber-reinforced polybenzoxazine/epoxy nanocomposites for low dielectric and flame-retardant applications
In the present work, a halogen-free flame-retardant cyclotriphosphazene nanofiber-reinforced polybenzoxazine/epoxy (PBZ/EP/PZT) hybrid nanocomposites have been developed and characterized. Initially, equimolar quantities of benzoxazine and the epoxy matrix is blended and varying weight percentages (0, 0.5, 1.0 and 1.5wt%) of PZT nanofiber are reinforced to obtain hybrid nanocomposites. It was observed that PBZ/EP/PZT nanocomposites possess higher values of glass transition temperatures (T(g)208 degrees C) and displayed enhanced thermal stability with high char yields than those of neat matrix. The flammability characteristics of the nanocomposites were studied on the basis of the LOI, UL-94 burning experiments as well as the analysis of residual chars of the tested bars after burning. The V-0 classification for the nanocomposites indicates that the incorporation of PZT nanofiber (1.5wt%) imparts enhanced flame retardancy to the PBZ/EP matrix. The dielectric properties of these nanocomposites have been studied at 1MHz over the temperature range between 30 and 200 degrees C. Data resulted from thermal, flame-retardant and dielectric studies indicate that the composite materials can be considered as the potential candidate for thermally stable fire and heat resistant, dielectric sealants, and encapsulants in electronic applications.