Polyester polyols for water-resistant polyurethane coatings

The mechanical properties of dimer-based urethanes on elastomers made by 1-part polyol, 2-parts chain extender (butane diol) and 3-parts MDI show that the dimer technology offers some unique benefits. Figure 5 shows the mechanical properties of various PU elastomers as modulus vs. elongation. This graph shows that the modulus at 100% is comparable for all polyester and polyether polyols; the dimerates perform just as well as any other polyol. At 300% elongation, the picture is slightly different.