On the other hand, many studies show that the synergistic effects of some halogen-free flame retardant agents, such as ammonium polyphosphate (APP) (4-6), hyperfine magnesium hydroxide (
HFMH) (7), (8), and red phosphorus (9) with LDH, can enhance flame retardancy and reduce the high loading level of LDH and thus improve the mechanical properties of the flame retardant materials.