Relationship between mechanical properties and exfoliation degree of clay in polyurethane nanocomposites

Abstract

AbstractExfoliated and intercalated polyurethane (PU) nanocomposites were prepared by in situ polymerization of polyol/organoclay mixture, chain extender and diisocyanate. Wide‐angle X‐ray diffraction and transmission electron microscopy confirmed an exfoliated structure for clay C30B and an intercalated structure for C20A in polyol and PU. The realization of exfoliated state for clay C30B in polyol during the mixing stage can provide an effective approach for controlling the exfoliation degrees by adjusting the content of intercalated and exfoliated organoclay C20A and C30B before polymerization. The effect of exfoliation degree on the mechanical and viscoelastic properties of PU was investigated. The addition of organoclay improved the tensile strength, modulus and elongation, but the hysteresis loss ratio and relaxation rate increased, and the relaxation time distribution became broad. The effect of organoclay on PU properties varied with the hard segment content. By increasing the exfoliation degree, the tensile strength and modulus increased, whereas the elongation decreased. The exfoliated PU nanocomposite had a lower relaxation rate and hysteresis loss ratio than the intercalated PU. Copyright © 2005 Society of Chemical Industry