Bismuth oxyiodide nanorods towards improvements in fire safety and mechanical properties of natural rubber

Abstract

Fire safety represents an enduring challenge in the realm of polymer-based nanocomposites, significantly limiting their application. The utilization of bismuth oxyiodide in flame retardant applications offers advantages such as increased surface area for improved interaction with combustible materials, the formation of a uniform flame retardant layer at the interface, and enhanced thermal stability. Hence, this work explored a facile strategy to synthesize bismuth oxyiodide nanorods by hydrothermal method combined with ball milling in anticipation of constructing an efficient flame retardant system. The bismuth oxyiodide nanorods dispersed relatively uniformly in the natural rubber matrix and endowed natural rubber nanocomposites with enhanced mechanical properties and fire-safety. The resultant natural rubber nanocomposite containing 5 wt% of bismuth oxyiodide showed a 36 % improvement in the tensile strength and a 39 % increase in the tear strength compared to those of the neat natural rubber. Cone calorimeter tests revealed that the introduction of 5 wt% bismuth oxyiodide to natural rubber matrix remarkably reduced the peak of heat release rate and peak smoke production release by 22 % and 25 %, respectively. A rational flame retardant mode of action for bismuth oxyiodide nanorods was proposed based on the analysis of pyrolysis fragments and char residues. Hence, this work provides a green and feasible method to prepare bismuth oxyiodide nanorods for flame retardant natural rubber products.