Facile fabrication of a novel polyborosiloxane-decorated layered double hydroxide for remarkably reducing fire hazard of silicone rubber

Abstract

How to improve the flame-retardant efficiency and dispersion of layered double hydroxide (LDH) in silicone rubber (SR) is one of the biggest challenges for the application of halogen-free flame retardant SR/LDH nanocomposite. In this work, a novel and highly efficient flame retardant, i.e., polyborosiloxane decorated layered double hydroxide (PBS-d-LDH), was synthesized and incorporated into SR to prepare SR/PBS-d-LDH nanocomposite. Benefitting from the sulfonate and boron hydroxyl groups of PBS, PBS-d-LDH was easily exfoliated and dispersed in SR. PBS-d-LDH endowed SR with outstanding mechanical properties, thermal stability, flame retardancy and smoke suppression performance. When the content of PBS-d-LDH was only 5.0 phr, SR/PBS-d-LDH had a good self-extinguishing capability, and its peak heat release rate and peak smoke production rate were reduced by 54.4% and 61.5%, respectively. Furthermore, the Ti (temperature at 5% weight loss) and the residue of SR/PBS-d-LDH at 700 °C were increased by 37.0 °C and 23.5 wt%, respectively. The mechanism analysis revealed that when being burned, the crosslinking reaction of PBS and layer barrier effect of LDH showed a good synergism in the ceramization of condensed phase, which contributed to the prominent flame retardancy and smoke suppression of the SR/PBS-d-LDH nanocomposite. This work provides a promising strategy to prepare highly efficient flame retardant polymer.