Compósitos de polietileno de alta densidade com resíduos de rocha ornamental de diferentes origens para aplicação na construção civil

Abstract

The use of mineral reinforcements in polymer matrix composites has emerged as an alternative for sustainable production, reducing waste and enhancing the physical and mechanical properties of these materials. This study investigated the impact of the melt flow index (MFI) of HDPE and the particle size of two mineral reinforcements, Beige Bahia (BB) and Limestone from Rio Grande do Norte (CRN), in the composites. All composites were processed by extrusion, followed by injection molding, with the addition of 30% by weight of reinforcement. Chemical analyses revealed similar compositions, with a high calcium oxide (CaO) content in the minerals, while X-ray diffraction (XRD) identified predominantly calcite, dolomite, and quartz phases. Statistical analysis indicated that the regression models for density, hardness, impact strength, tensile strength, and elastic modulus are highly predictive (adjusted R² > 90%). The most influential factors were the melt flow index and particle diameter, while the rock residue affected only density and impact strength. In summary, the optimal composite composition for future applications includes both Beige Bahia Limestone and Rio Grande do Norte Limestone with particle sizes between 20 and 40 µm and HDPE with an MFI of 7 g/10min. This combination is expected to enhance the mechanical properties and overall performance of the composite material. It is recommended to use these composites in flooring and coatings in the civil industry.