Cyclotriphosphazene nanofiber-reinforced polybenzoxazine/epoxy nanocomposites for low dielectric and flame-retardant applications

• Published in: Polymer bulletin (Berlin, Germany) Germany), 2019-07, Vol.76 (7), p.3785-3801
• Main Authors: Selvi, M., Devaraju, S., Alagar, M.
• Format: Article
• Language: English
• Subjects: Benzoxazines; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Complex Fluids and Microfluidics; Dielectric properties; Epoxy resins; Fire resistance; Flame retardants; Flammability; Glass substrates; Glass transition temperature; Heat resistance; Incorporation; Morphology; Nanocomposites; Nanofibers; Nitrogen; Organic Chemistry; Original Paper; Phosphorus; Physical Chemistry; Polybenzoxazines; Polymer Sciences; Polymers; Soft and Granular Matter; Thermal stability
• ISSN: 0170-0839; 1436-2449
• DOI: 10.1007/s00289-018-2569-6

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 1.5 wt%) 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 °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 (1.5 wt%) imparts enhanced flame retardancy to the PBZ/EP matrix. The dielectric properties of these nanocomposites have been studied at 1 MHz over the temperature range between 30 and 200 °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.