Chapter 32 - Polybenzoxazines with Enhanced Flame Retardancy

Abstract

This chapter captures the general synthesis and material properties of some important polybenzoxazine systems incorporating heteroelements such as bromine, phosphorus, and silicon, which are known to confer flame retardancy. It focuses on those containing phosphorus and silicon because they exhibit improved properties and have a bright future. The investigation of flame retardancy of silicon-containing benzoxazine systems is in an early phase of development. Clearly, more work needs to be done to fully exploit these materials. The design of new precursors should be developed by linking these heteroelements to introduce new properties of interest for potentially useful compounds. Flaming combustion proceeds if the exothermic gas-phase combustion reactions generate sufficient energy in the form of heat transferred back to the condensed phase to decompose the polymer further, thus producing more fuel and so maintaining the combustion cycle. Polybenzoxazines have attracted considerable attention in preparing high performance resins because of their fascinating characteristics such as no release of volatiles during cure, good thermal stability, and flame retardancy. Although carbon fiber reinforced polybenzoxazine shows improved flame retardancy, the flame retardancy of neat polybenzoxazines may not meet the requirements of certain electronic applications. Therefore, polybenzoxazines with high flame-retardant properties have attracted much attention owing to the increased demands for electronic materials.