Preparation of hexakis (4-aldehyde phenoxy) cyclotriphosphazene grafted kaolinite and its synergistic fire resistance in poly (butylene succinate)

Hexakis (4-aldehyde phenoxy) cyclotriphosphazene (HAPCP) was synthesized firstly and then it was grafted onto the exfoliated kaolinite (Kaol) to prepare K-HAPCP. The structure of HAPCP and K-HAPCP was well characterized. K-HAPCP was used as synergistic agent in poly (butylene succinate) (PBS)/intumescent flame retardants (IFR) composites. The combustion behavior of PBS composites was reflected by limited oxygen index (LOI), vertical burning (UL-94), and cone calorimeter test. The thermal stability was traced by thermogravimetric analysis. PBS is highly flammable with the LOI value of only 21.9% and cannot pass any UL-94 grade during vertical burning test. By the presence of 22 wt% IFR and 3 wt% K-HAPCP, the LOI of PBS composite is sharply increased to 40.3% and the sample can pass UL-94 V-0 rating with excellent anti-dripping properties. Moreover, the degradation behavior is investigated and the probable flame retardant mechanism is also proposed.