Effects of the reagent ratio on the properties of waterborne polyurethanes-acrylate for application in damping coating

Hybrid emulsions of waterborne polyurethanes-acrylate (WPUA) were synthesized using isophoronediisocyanate (IPDI), polytetramethylene glycol (PTMG), and an acrylate monomer as the main materials. The influence of the NCO/OH ratio (R value) and PU/PA ratio on different properties of the WPUA hybrid emulsions and films was investigated using dynamic light scattering (DLS), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), contact angle measurements, mechanical tests and dynamic mechanical analysis (DMA). DLS and TEM results showed that all WPUA latex particles display regular spheres and excellent stability. DMA indicated that when the PU/PA ratio was 30/70 and the R value was 1.2, the loss factor (tan delta) was >= 0.3 spanning a temperature range of 75 degrees C with a maximum value of 1.2. The WPUA films could be used as materials for damping applications.