Zirconium phosphate functionalized by hindered amine: A new strategy for effectively enhancing the flame retardancy of addition-cure liquid silicone rubber

• A new strategy for effectively enhancing the flame retardancy of ALSR was proposed.
• F-ZrP could significantly improve the flame retardancy of ALSR.
• The catalyzing carbonization and free-radical quenching mechanism was combined.

Functionalized zirconium phosphate (F-ZrP) was prepared by intercalating 1,2,2,6,6-pentamethyl-4-(vinyldiethoxysiloxy) piperidine (PMVP) into α-zirconium phosphate (α-ZrP), and was used to flame-retard addition-cure liquid silicone rubber (ALSR). X-ray diffraction (XRD) and transmission electron microcopy (TEM) were used to characterize the structural morphology of F-ZrP and ALSR/F-ZrP. The results indicated that PMVP was successfully intercalated into α-ZrP, and F-ZrP existed with a structure of the intercalated and exfoliated components in the ALSR matrix. F-ZrP could significantly improve the flame retardancy of ALSR. When only 4 phr of F-ZrP was added, the flame-retardant ALSR could pass the UL-94 V-0 rating with the LOI value of 31.0%. Such an efficient flame retardancy of F-ZrP was attributed to the synergism of the catalyzing carbonization and free-radical quenching mechanism.