Mixtures of Polyester Polyol and Polycarbonate Diol for Synthesizing Polyurethanes Urea Waterborne Adhesives with Improved Properties and Aging Resistance

摘要

Waterborne polyurethane urea dispersions (WPUUs) were synthetized with mixtures of polyester polyol and polycarbonate diol of similar molecular weights. WPUU dispersions were characterized by particle size distribution, viscosity and pH. The chemical structure of the polyurethane urea (PUU) films was evaluated by ATR-IR spectroscopy and their crystallinity, thermal and viscoelastic properties were also determined. Adhesion was assessed by T-peel tests of surface chlorinated vulcanized SBR rubber/WPUU/roughened leather joints, before and after severe aging (immersion in water at 70°C for different periods of time). The WPUUs made with mixtures of polyols had higher mean particle size and lower viscosity than the ones made with one polyol only. The properties of the PUUs made with mixtures of polyols were affected by their content in polycarbonate diol and were determined by the lower degree of phase separation and the interactions between hard and soft domains via carbonate groups. The severe aging did not decrease the T-peel strength of joints prepared with WPUUs made with 25 wt% or less polycarbonate diol in the mixture of polyols.