Preparation and characterization of polyphosphazene-based flame retardants with different functional groups

Abstract

To study the effect of polyphosphazene nanocomposites with different functional groups on the flame retardancy of polyethylene terephthalate (PET), poly-(cyclotriphosphazene-co-4,4′-sulfonyldianiline) (PDS) and poly-(cyclotriphosphazene-co-4,4′-sulfonyldiphenol) (PZS) containing amino and hydroxyl groups, respectively, were synthesized. Molecular simulation and experimental results showed that the hydrogen bonding and π–π interactions between PDS and PET were lower than those between PZS and PET. The weaker interactions caused the cross-linking network between PDS and PET to collapse readily, leading to a more significant dripping phenomenon; however, they did not cause secondary combustion. After adding 5 wt% PDS, the limiting oxygen index value of PET composites increased to 33.1%, and they passed the UL-94 V-0 test. PDS exhibited better flame retardancy than PZS.