X-ray diffraction detection of compliance in polyurethane – organoclay nanocomposites

Abstract

High performance polyurethane elastomer – organically modified layered silicate (organoclay) nanocomposites based on poly(propylene glycol), 4,4′-methylene bis(cyclohexyl isocyanate), 1,4-butandiol and organoclay have been prepared. The tensile strengths and strains at break of these polyurethane elastomer nanocomposites increased by more than 150% related to the unfilled polyurethane. The fatigue properties were also very significantly improved. The existence of a ‘nano-spring’ in the polyurethane – organically modified layered silicate nanocomposites has been found for the first time. During stretching, the separation of the clay interlayers intercalated by polyurethane chains increased. When the stretching force was removed, the interlayer spacing returned to the original value under elastic deformation of the polyurethane sample. This finding has been used to understand why the fatigue life of polyurethane incorporated with the clay is significantly enhanced. The new understanding can be applied to the design of important new damping materials.