Multifunctional Additive: A novel regulate strategy for improving mechanical property, aging life and fire safety of EVA composites

• A multifunctional additive (MCMH) is carefully designed. • The microencapsulation technology improves the compatibility between MCMH and XLEVA. • The OIT value of XLEVA/MCMH was basically unchanged after extracted for 5 days. • The retention of EB of XLEVA/MCMH could reach 71.8% after aging at 165 °C for 14 days. • The PHRR and Ds max of XLEVA/MCMH are reduced by 89.4% and 53.6%, respectively. A multifunctional additive is carefully designed for crosslinked ethylene–vinyl acetate copolymer (XLEVA) composites to improve their mechanical properties, aging resistance and fire safety. In this study, first, a layer of silica was microencapsulated on magnesium hydroxide to give a large amount of hydroxyl group on the magnesium hydroxide surface; second, the primary antioxidant 3-(3, 5-di- tert -butyl-4 hydroxyphenyl) propionicacid was grafted on SiMH surface to prepare antioxidant microencapsulated flame retardants (MCMH). Compared with the pure XLEVA, the peak heat release rate and the maximum smoke density of flame retardant XLEVA/MCMH are decreased by 89.46% and 53.6%, respectively. Moreover, these oxidation induction time values of XLEVA/MH/AO and XLEVA/SiMH/AO decreased sharply after extracted for 1d. However, the OIT value of XLEVA/MCMH was basically unchanged after extracted for 5d. After aging at 165 °C for 14 days and γ-ray irradiation dose of 500 kGy, the retention of elongation at break could reach 71.8% and 86.6%, showing excellent aging resistance. These results show that MCMH has a good synergistic effect for enhancing the flame retardant, mechanical property as well as aging resistance of XLEVA composites. The “Killing three birds with one stone” strategy provides an excellent solution for obtaining high-performance XLEVA cable materials.