Study on the Mechanical and Thermal Properties of Waterborne Polyurethane-Modified Aluminum Hydroxide and Its Application in LDPE Plastics

This study investigates the modification of aluminum hydroxide (ATH) powder using waterborne polyurethane (WPU) as a novel modifier, along with its subsequent effects on the dispersion, mechanical properties, and thermal performance of ATH-filled low-density polyethylene (LDPE) composites. ATH was modified through an optimized wet process, and the modification efficiency was evaluated using various characterization techniques, including scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). The results show that WPU, as a modifier, effectively improved the dispersion of ATH in the organic phase, as demonstrated by the reduced settling time and enhanced interfacial compatibility between ATH and LDPE. The modified ATH demonstrated enhanced mechanical properties in LDPE-based composites, with a tensile strength of 30.02 MPa, flexural strength of 13.20 MPa, impact strength of 65.75 kJ/m², and elongation at break of 59.84%, all reaching their maximum at 3.0 wt.% WPU modification. Additionally, the flame retardancy of the composites was significantly improved due to the incorporation of ATH, with the ATH content in the composites reaching up to 60%, further enhancing their fire resistance. This study highlights the effectiveness of WPU-modified ATH as both a flame retardant and a reinforcing filler for LDPE composites, offering potential advantages in enhancing material properties while reducing manufacturing costs.