Study on the flame retardancy and properties of magnesium hydroxide reinforced HDPE/EVA blends

As an environmentally friendly halogen-free flame retardant, magnesium hydroxide (Mg(OH)₂) shows great potential in the flame retardant modification of polymer materials due to its excellent flame retardant efficiency and environmental friendliness. This study aims to analyze the effect of magnesium hydroxide on the flame retardant effect, microstructure and mechanical properties of high-density polyethylene (HDPE) and ethylene-vinyl acetate (EVA) blends.

Keywords: magnesium hydroxide, HDPE/EVA blends, flame retardant efficiency, microstructure, mechanical properties

Introduction Magnesium hydroxide, as an efficient halogen-free flame retardant, is gradually replacing traditional halogen-containing flame retardants. HDPE/EVA blends are widely used as thermoplastic elastomers, and their flame retardant modification is crucial to improve material safety. This study aims to improve the flame retardant properties of the blends by adding magnesium hydroxide, while reducing the smoke and toxic gases generated during combustion.

Experimental methods Sample preparation: Magnesium hydroxide was doped into HDPE/EVA blends in different proportions (30-60 wt%) by melt blending to prepare a series of composite materials. Performance evaluation: The flame retardant properties of the composites were tested using techniques such as limiting oxygen index (LOI), cone calorimetry test (CCT) and thermogravimetric analysis (TGA); the microstructure of the materials was observed using scanning electron microscopy (SEM); and the mechanical properties were evaluated by tensile tests.

Results and analysis

Flame retardant properties: The study found that with the gradual increase in the content of magnesium hydroxide, the LOI value of the composite increased and the heat release rate decreased, showing a better flame retardant effect.

Microstructure: SEM observation showed that magnesium hydroxide was evenly dispersed in the HDPE/EVA blend, and its addition significantly changed the micromorphology of the material.

Mechanical properties: Although the addition of magnesium hydroxide enhanced the flame retardant properties of the composites to a certain extent, it also led to a decrease in mechanical properties, especially at higher contents.

Studies have shown that the addition of magnesium hydroxide plays an important role in improving the flame retardant properties of HDPE/EVA blends. However, it is also necessary to note the possible adverse effects of magnesium hydroxide on material processing and mechanical properties. Therefore, in the design and application process, it is necessary to balance the flame retardant properties and mechanical properties, and select an appropriate amount of magnesium hydroxide to meet the requirements of specific applications.