The synergistic effect of sepiolite-LDH hybrid nanofiber and phytic-based nanosheet towards improving the fire retardancy, heat resistance, and mechanical properties of epoxy resin

Abstract Usually, it is difficult to achieve satisfactory fire retardancy of epoxy resin at low addition by adding inorganic nano-fillers alone. Herein, sepiolite nanofibers loaded with layered double metal hydroxide (a-SEP@LDH) and P/N-containing flame retardant nanosheet (PAMA) were prepared via hydrothermal method, respectively. The UL-94 V-0 rating and an LOI value of 31.6% were achieved for EP by loading 1wt% a-SEP@LDH and 2wt% PAMA. Compared to adding sole a-SEP@LDH, the thermal stability of EP/a-SEP@LDH/PAMA was improved significantly, the total heat release (THR) and peak heat release rate (pHRR) decreased by 10.2% and 28.8%, respectively. Additionally, the total CO2 production decreased by 12.5% and the char residue yield increased to 19.9wt%. Moreover, the tensile strength and impact strength of the EP composites were remarkably improved owing to the incorporation of PAMA. To sum up, this work provides an environmentally benign, low-cost and efficient way for EP to achieve outstanding fire retardance, excellent thermal stability and high mechanical properties at a low addition.