Preparation of environmentally-benign, hydrophobic, phosphorus-/halogen-free, mono-component and hydromagnesite-based flame retardant for intensifying the fire safety of silicone rubber

Aimed at settling the adverse effect of halogen−/phosphorus-containing flame retardants on the human health and ecological environment, a hydromagnesite (HM)-based flame retardant was prepared via sequential modification of polydopamine (PDA) and layered double hydroxide (LDH), which was expected to enhance the flame retardancy of silicone rubber (SR). The preparation feasibility for HM@PDA@LDH were confirmed by a series of characterizations in view of chemical composition, surface morphology, wettability and thermal degradation. The flame retardancy of 20 parts of HM@PDA@LDH per one hundred of silicone rubber (SR/20 phr HM@PDA@LDH) was upgraded with limiting oxygen index (LOI) of 30.5 %, Underwriters Laboratories-1894 Vertical burning-0 (UL-94 V-0) rating and peak heat release rate (PHRR) reduction of 59.6 % in comparison with neat SR. Besides, the possible mechanism was proposed by investigating the combustion residues of SR composites. Along with durable flame retardancy and maintained mechanical strength, the good balance among comprehensive properties of SR composites was gained. Thus, this paper proposed a valuable strategy for overcoming the contradiction between flame retardancy and environmental pollution, which was feasible for the real-world application of SR materials.