Structural characterization of polyurethane ureas and waterborne polyurethane urea dispersions made with mixtures of polyester polyol and polycarbonate diol

Abstract

Waterborne polyurethane urea dispersions (WPUUs) intended for coatings and adhesives were synthesized with mixtures of polyester polyol (PE) and polycarbonate diol (PCD) for combining the advantages of the polyurethane ureas made with pure polyols. WPUUs made with mixtures of polyols had higher mean particle size and lower viscosity than the ones made with one polyol only. Two types of hard segments totally separated (i.e. −(IPDI-DMPA/TEA-IPDI)- and −(IPDI-HZ-IPDI)-) and two types of soft segments (i.e. −(IPDI-PCD-IPDI)- and −(IPDI-PE-IPDI)-) were produced in polyurethane ureas made with PE + PCD mixtures. The segmented structure and phase separation of the polyurethane ureas made with PE + PCD mixtures differed depending on their PCD content, affecting the thermal, rheological and crystallinity properties. The adhesion of chlorinated vulcanized styrene-butadiene rubber/WPUU/roughened leather joints made with WPUUs prepared with PE + PCD mixtures was very similar to the ones made with PCD and PE only. After ageing in water at 70 °C for 1-2 days, the adhesive strength of joints made with WPUUs containing more than 50 wt% PCD is excellent. The properties of the polyurethane ureas made with mixtures of polyols containing 50 wt% or more PCD were determined by lower degree of phase separation and interactions between hard and soft domains via carbonate groups.