Investigation on guanidine phosphate modified LDH and its flame-retardant mechanism in cellulosic composites

Layered double hydroxides (LDH) was proved as preferable retardants for lignocellulosic materials . In this study, Mg/Al-LDH was selected and one-step modified by GP which exhibited superior characteristics of flame retardancy and non-toxicity. Results showed that more complete two-dimensional layered structure with suitable crystal particle size was formed for GP modified LDH. Specifically, GP 3 -LDH not only enhanced the thermal stability of cellulosic composites, but also assisted the peak heat release rate (PHRR) and total heat release (THR) in declining 42.5% and 22.7% compared with those added with non-modified Mg/Al-LDH. In addition, the limiting oxygen index (LOI) achieved as high as 27.7% with 15 wt% addition, indicating the successful modification with GP for outstanding flame-retardant performance, low addition and controlled strength of cellulosic composites. • GP was inserted into the interlayer of LDH through simple one-step modification. • Two-dimensional crystalline structure with suitable crystal particle size was formed. • The outstanding flame-retardancy and controlled strength exhibited with low addition.