Inorganic PIN FRs for cable sheathing

Three different aluminium and magnesium hydroxides were tested in EVA//LLDME/MA polyolefin cable sheath compound at 60% loading. The PIN FRs tested were synthetic (precipitated) aluminium and magnesium hydroxides and a milled mined mineral magnesium hydroxide (ATH, MDH). They were tested in a polyolefin compound consisting of EVA (ethylene vinyl acetate), LLDPE (linear low density polyethylene) and maleic acid grafted LLDPE, with an antioxidant (pentaerythritol tetracid) and a silicone lubricant. All three PIN FRs provided effective fire performance (reduction of peak heat release rate pHHR of more than 80%) and reduced smoke emission (50 – 70% lower). The metal hydroxides also slightly reduced UV deterioration of the polymer. The different mineral composition, fire performance parameters and processing behaviours of the three inorganic PIN FRs are analysed.

“Sustainable and efficient metal hydroxides as halogen-free flame-retardant additives in polyolefin-based composites for cable sheathing applications”, G. Infurna et al., J. Physics and Chemistry of Solids 211 (2026) 113458 https://doi.org/10.1016/j.jpcs.2025.113458