Effect of in-situ Incorporated Silica Particles on Properties of Polyurethane Elastomer

This study explores the in-situ incorporation of silica (SiO₂) microparticles into a hard-soft segmented polyurethane (PU) matrix to enhance its properties for potential coating applications. The structural characterization of the material was conducted using Fourier Transform Infrared (FTIR) spectroscopy, X-ray Diffraction (XRD), and Field Emission Scanning Electron Microscopy (FE-SEM) studies. In the FTIR spectra, the C = O absorption peaks in urethane at 1707 and 1726 cm⁻¹ for PU-Neat film shift to 1702 and 1716 cm⁻¹ in PU-SiO₂, indicating H-bonding between polyurethane and SiO₂. The optical, thermal, and mechanical properties of the material were evaluated through transmittance, haze measurement, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and mechanical analysis. The results demonstrated that adding SiO₂ microparticles significantly improved the thermal stability, and the glass transition temperature (T_g) increased from 2.52 °C to 3.0 °C due to the incorporation of SiO₂ particles, as analyzed from DSC; these results are supported by DMA findings. The silica-incorporated polyurethane demonstrated significantly higher resistance to scratching, with a threshold load of 1800 g compared to PU-Neat (1000 g). The PU-SiO₂ composite exhibited a higher maximum decomposition temperature (T_max, 393.9 °C) and increased tensile strength (21.21 MPa) compared to neat PU. Enhanced thermal conductivity (1913.91 W/cm.^oC) and mechanical properties were attributed to the uniform dispersion of silica microparticles within the matrix, as confirmed by FE-SEM analysis. These findings indicate that SiO₂-incorporated polyurethane composites are promising candidates for hard coating applications requiring enhanced durability and performance under mechanical stress.