Preparation and Properties of Silicate/Phosphazene Synergistic Flame-Retardant Polyolefin Cable Compound

Aiming at the long-standing scientific and technological dilemma among flame-retardant efficiency, mechanical properties and processability in traditional halogen-free flame-retardant polyolefin materials, this study innovatively proposes a synergistic flame-retardant system based on silicate nanocomposites and phosphazene compounds. On this basis, high-performance halogen-free low-smoke flame-retardant cross-linked polyolefin insulation compounds and thermoplastic polyolefin sheath compounds were developed. The synergistic flame-retardant mechanism of the composite flame retardants and the optimization schemes for material preparation technology were systematically investigated. Key indicators such as cross-linking degree, hot-set performance, flame retardancy, smoke density, heat-release characteristics and mechanical properties were comprehensively characterized. Results show that, compared with conventional single flame-retardant systems, the composite flame-retardant system proposed in this study significantly improves flame retardancy (limiting oxygen index≥34%, UL-94 V-0 rating) and bundle-flame-retardant performance (char height≤1.5 m) while maintaining good processability. Meanwhile, the peak heat-release rate is reduced by more than 40%, and the light transmittance in smoke-density tests increases by 20%. In addition, thermal stability and mechanical properties of the materials are markedly enhanced, offering a new concept and theoretical basis for the development of high-performance environmentally friendly cable materials.