Nanoclay modification of shape memory polyurethane

Effect of nanoclay modification on the properties of polytetramethylene oxide-based polyurethane was examined. Nanoclay was dispersed in polyurethane wherein the clay content was varied from 1 to 5 wt.%. The nanocomposites were characterized by thermal, FTIR, XRD and thermo-mechanical analyses and their shape memory properties were evaluated. Morphology was examined by TEM analysis. Bending test was adopted for the evaluation of shape memory property. Increase in clay content resulted an increase in transition temperature. Tensile strength and modulus increased proportional to nanoclay content. The elongation decreased with clay content. Intercalated structure of clay in the PU matrix was observed from XRD studies, which was confirmed by TEM analysis. Modulus ratio showed a decreasing trend with nanoclay content. This resulted in decreased shape recovery characteristics. Highest shape recovery of 92% was observed for PU with 1 wt.% clay content. Moderate nanoclay leveling is conducive to deriving mechanically stronger PU without loss of shape memory characteristics.