Effect of clay modification on the morphological, mechanical, and thermal properties of epoxy/polypropylene/montmorillonite shape memory materials

A series of montmorillonite (DK2) modified shape memory polyurethane-epoxy (UEP) composites had been prepared. The effect of DK2 modification on the morphological, mechanical and thermal properties of epoxy/polypropylene/Montmorillonite nano-composites were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), tensile test, scanning electron microscope (SEM) and dynamic mechanical analysis (DMA). The shape memory performance was investigated by fold-deploy shape memory tests. The XRD and TEM results indicated the formation of exfoliated structure for epoxy/polypropylene nano-composites had been prepared using 2~ 3wt.% DK2. On the other hand, a mixture of intercalated and exfoliated structure was found in 4~5wt.% DK2/ epoxy/polypropylene polymers. Further more, the toughness, tensile strength, enlongation at break had been improved by adding DK2, while glass transition temperature, storage modulus and shape recovery ratio was unaffected. The composite materials possessed excellent shape memory properties, they could fully recover their original shapes within 3 min under the maximum bending angle of 180°, and there were little effect by fold-deploy ten times.