Enhancing Mechanical and Flame‐Retardant Properties of Huntite‐Hydromagnesite Reinforced Polypropylene Composites With Calcite, Zeolite and Intumescent Flame Retardants

ABSTRACT As firefighting efforts increase daily, the use of fire‐resistant materials is also on the rise. However, those materials sometimes create other problems. The discovery that halogenated fire retardants are toxic is one example. Another issue is that inorganic minerals used to provide fire resistance can degrade some mechanical properties in polymer composites. This study aims to prevent the deterioration in mechanical properties caused by the high amount used of huntite and hydromagnesite minerals. In this context, polypropylene‐based composites were developed using huntite‐hydromagnesite, calcite, zeolite, and an intumescent flame retardant. Seventeen different formulations were prepared by twin‐screw extrusion and hot pressing, and then their thermal, mechanical, and flame‐retardant properties were characterized. It was concluded that flame retardancy, as assessed by the UL94 test, reached a V0 rating with only 40% huntite‐hydromagnesite, compared to the conventional 60% load with 10%–20% calcite, zeolite, and intumescent flame retardant. LOI values exceeded 29%, demonstrating strong flame retardant performance. Furthermore, as the main objective of this study, it was observed that tensile strength increased from 23.6 ± SD MPa for HH‐only composites to 25.7 ± SD MPa for hybrid formulations, indicating partial recovery relative to HH‐filled systems. All mechanical properties remained inferior to neat polypropylene.