ZnO nanoparticles have a very special property in that they
have no detectable surface water compared to other metal oxide
nanoparticles, such as Al2O3, TiO2, and SiO2. This characteristic
enables ZnO nanoparticles to induce crystallization of
Nylon 6 on the particles’ surface [7] and to react with the isocyanate
groups of the polyurethane prepolymer [8]. Because
of the reaction between the isocyanate groups of the polyurethane
prepolymer and ZnO, the mechanical behavior of the
polyurethane/ZnO nanocomposites is quite unique. Detailed
studies on the nanocomposites of polyurethane with ZnO particles
of different sizes and surfaces have been reported in our
previous publication [8]. A brief description of the results will
be presented in the following paragraphs. Some of the data are
listed in Table 1.