(186c) Nanocomposites of Polyurethane Elastomers for High-Rate and Large-Strain Applications

Elastomeric materials with high stiffness, strength and ductility are desirable for impact loading like blast and ballistic events. We have fabricated nanocomposites of a series of polyurethane elastomers with the same types of hard and soft segment but different concentration, and different chain extenders. A solvent exchange method was used in preparation of nanocomposites. The formed nanocomposites were extensively characterized by transmission electron microscopy, X-ray diffraction, differential scanning calorimetry, dynamic mechanical analysis, tensile testing, and split Hopkinson pressure bar techniques. Our results show that good exfoliation of the clay was achieved, and that the well-exfoliated nanocomposites have dramatically improved moduli (in some cases, the increase in moduli is about 16 fold). The stress-strain behavior at both low and high rates of the nanocomposites shows non-linear behavior, and the nanocomposites show higher stress levels than the neat polyurethane materials. At high strain rates, the polyurethane nanocomposites seem to be insensitive to rates.