Experimental Characterization of the Effects of Mineral‐Based Fire‐Retardant Admixtures on the Combustion Properties of Polyethylene Blends

The growing demand for flame retardant (FR) polymeric materials has highlighted the need to improve the combustion behaviour of highly flammable polymers such as polyethylene (PE). This study investigates the use of eco‐sustainable mineral FRs as a strategy to reduce heat release and smoke production during combustion, while improving the thermal stability of the material. Two types of FR powders—magnesium hydroxide (Mg(OH) 2 ) and aluminum hydroxide (Al(OH) 3 )—were added to the PE matrix in varying weight percentages (60%, 70%, and 80%) to produce different composite formulations. The experimental investigation focuses on the characterization of the thermal and fire behaviour of the samples through a combination of testing techniques. Cone calorimetry was used to evaluate combustion parameters such as heat release rate and smoke production. Differential scanning calorimetry (DSC) analyses, conducted in both air and nitrogen atmosphere, provided information on thermal transitions and oxidative stability. Thermogravimetric analysis coupled with FTIR spectroscopy (TG‐FTIR) was used to identify volatile products generated during degradation. Finally, bomb calorimetry, performed on solid residues after combustion, allowed the quantification of the residual energy content. The results highlight the remarkable effectiveness of mineral FRs in softening the unstable combustion dynamics of PE blends, experimentally characterized also exploring the scale effect. A comparative analysis between different blends and PE quantified the role of both FR type and percentage in modifying the thermal response of the material.