A double encapsulation strategy for enhancing the comprehensive performance of PO cable materials

Traditional polyolefin (PO) flame-retardant cable materials face challenges such as low flame-retardant efficiency and poor mechanical properties, particularly when environmentally friendly magnesium hydroxide (MH) is added. Herein, this work presents a novel approach to enhancing flame-retardant PO cable materials through a dual encapsulation strategy for MH. The double-encapsulated MH (HZM) was synthesized by depositing zinc hydroxy stannate, followed by microencapsulation using supramolecular polyphosphazene compounds. The PO composites achieved a V-0 rating with the addition of 56 wt% HZM, whereas the PO materials received no rating with the same loading of pure MH. Combined with the dual advantage of ZHS and supramolecular layer, the peak heat release rate and total heat release of PO-HZM decreased by 71.5% and 36%, respectively. HZM also exhibited outstanding smoke suppression (total smoke, CO₂, and CO) of PO composites. Furthermore, compared to PO-MH, the mechanical properties of PO-HZM had been strengthened because of the enhanced compatibility between HZM and PO matrix. Therefore, the double encapsulation of MH offers an effective strategy for developing revolutionary PO cable materials with enhanced comprehensive performance.