Preparation of kaolin-modified polyurethane elastomer composites and synergistic enhancement of mechanical, damping, and sound insulation properties

Using the semi-prepolymerization method as the core process, a series of kaolin/polyurethane elastomer composites were prepared. The effects of kaolin content and calcination temperature on the mechanical properties, damping, and sound insulation were systematically investigated. The results indicate that uncalcined kaolin exhibited optimal dispersion at a loading of 0.5 wt%, enhancing the mechanical performance of the composite relative to that of the neat matrix. When the filler content increased to 1 wt%, the damping properties improved markedly. The synergistic effect of the acoustic impedance mismatch and enhanced damping led to an overall improvement in sound insulation across the 50-6400 Hz frequency range, with samples with higher filler content exhibiting more pronounced performance. Calcination above 600 ℃ converted kaolin into metakaolin and improved its compatibility with the polyurethane matrix. When treated at 800 ℃, the resulting metakaolin composite attained a hydrogen-bonding index of 2.33, maintained a tensile strength of 11.9 MPa, and reached a tanδ value of 0.84, delivering the best overall synergy in mechanical and damping properties. A comprehensive analysis indicated that the synergistic control of kaolin content and calcination temperature significantly enhanced the strength, toughness, damping, and sound insulation properties of polyurethane elastomers. This provides new insights and technical pathways for designing and preparing lightweight, high-damping, and high-soundinsulation structural vibration-damping materials.