Effect of Porosity on the Mechanical and Physical Properties of Polyurethane

Polyurethane (PU) foam is a versatile polymerPolymer material known for its unique properties and widespread industrial applications. In this study, we investigate the influence of pore size variation on the microstructure and properties of PU foam. The PU foam samples were prepared using different mold types, namely open (LD), half-open (MD), and closed (HD) molds. PorosityPorosity measurements confirmed that HD foam possessed an average pore size of 119.82 µm, which was significantly smaller than the average pore sizes of MD (500.33 µm) and LD (708.69 µm) foams. The density of the PU foam samples exhibited a corresponding increase as the pore size decreased. This can be attributed to the presence of significant air gaps within the LD foam, resulting from the reaction between polyisocyanate and polyether in the open mold process. Furthermore, flexural testing was performed to evaluate the mechanical properties of the PU foam samples. The results demonstrated that the flexural strength of LD foam was lower than that of MD and HD foams. The superior flexural strength of HD foam (0.95 MPa) compared to LD foam (0.425 MPa) can be attributed to the smaller voids and higher density in the PU foam composition. The larger voids in LD foam rendered it more susceptible to bendingBending loads and decreased its resistance to such loads. This study provides valuable insights for engineering the manufacturing process of PU foam, allowing for tailored pore sizes and improved thermal insulation properties.