In-situ synthesis of a novel CaO·4B2O3 · 2H2O–SiO2 nanocomposite and its influence on mechanical property and flame retardancy of polypropylene

Abstract

A novel CaO·4B2O3·2H2O–SiO2 nanocomposite with good thermal stability has been in situ synthesized, in which the SiO2 nanospheres are supported on the CaO·4B2O3·2H2O nanosheets. As a comparison, single CaO·4B2O3 ·2H2O nanosheet with the thickness of 100 nm, single SiO2 nanosphere with the diameter of about 100 nm, and their physical mixture were also prepared, respectively. On the basis of characterizations of XRD, FT-IR, TGA, SEM and TEM, the fire performance of CaO·4B2O3 ·2H2O–SiO2 nanocomposite to polypropylene was studied. It is demonstrated that the flame retardancy of prepared sample was prominently stronger than those of single CaO·4B2O3 ·2H2O nanosheet and their physical mixture. Furthermore, the mechanical property of polypropylene/CaO·4B2O3·2H2O–SiO2 composite was also assessed. The possible formation mechanism of the nanocomposite and its flame-retardant mechanism were put forward. It has prospect as possible flame retardant to polypropylene and other polymers.