Shape memory polymers (SMP) feature the ability of the polymers to recover their original/permanent shape from deformed/temporary shape with the presence of stimulus such as heat, light, or vapor. Shape Memory Polyurethane (SMPU) reinforced with multi-walled carbon nanotubes (MWNTs) were fabricated with through mixing and injection molding with the purpose to improve the shape memory properties of the polymer at low filler content. Variables such as shape fixity and recovery have been measured to evaluate the effect of nanotube fillers on the shape memory behavior of the prepared composites. Thermomechanical test were performed and the shape fixity and shape recovery rate were analyzed. Additions of nanotube fillers increase the relative shape fixity of the polymer nanocomposites while the experimental results demonstrate that the presences of nanotube fillers reduce the shape recovery rate. The shape recovery of the polymer nanocomposites were decreased due to the limited movement of polymer chains by the MWNTs

This paper investigates the influence of silica nanoparticles on the mechanical properties of a unidirectional (UD) kenaf fiber reinforced polymer (KFRP) and hybrid woven glass/UD kenaf fiber reinforced polymer (GKFRP) composites. In this study, three different nanosilica loadings, i.e., 5, 13 and 25 wt %, and untreated kenaf fiber yarns were used. The untreated long kenaf fiber yarn was wound onto metal frames to produce UD kenaf dry mat layers. The silane-surface-treated nanosilica was initially dispersed into epoxy resin using a high-vacuum mechanical stirrer before being incorporated into the UD untreated kenaf and hybrid woven glass/UD kenaf fiber layers. Eight different composite systems were made, namely KFRP, 5 wt % nanosilica in UD kenaf fiber reinforced polymer composites (5NS-KFRP), 13% nanosilica in UD kenaf fiber reinforced polymer composites (13NS-KFRP), 25 wt % nanosilica in UD kenaf fiber reinforced polymer composites (25NS-KFRP), GKFRP, 5 wt % nanosilica in hybrid woven glass/UD kenaf fiber reinforced polymer composites (5NS-GKFRP), 13 wt % nanosilica in hybrid woven glass/UD kenaf fiber reinforced polymer composites (13NS-GKFRP) and 25 wt % nanosilica in hybrid woven glass/UD kenaf fiber reinforced polymer composites (25NS-GKFRP). All composite systems were tested in tension and bending in accordance with ASTM standards D3039 and D7264, respectively. Based on the results, it was found that the incorporation of homogeneously dispersed nanosilica significantly improved the tensile and flexural properties of KFRP and hybrid GKFRP composites even at the highest loading of 25 wt % nanosilica. Based on the scanning electron microscopy (SEM) examination of the fractured surfaces, it is suggested that the silane-treated nanosilica exhibits good interactions with epoxy and the kenaf and glass fibers. Therefore, the presence of nanosilica in an epoxy polymer contributes to a stiffer matrix that, effectively, enhances the capability of transferring a load to the fibers. Thus, this supports greater loads and improves the mechanical properties of the kenaf and hybrid composites.

The effect of nanosilica on the tensile stress-strain response of Epikote 828 epoxy polymer was studied. A 40 wt% nanosilica/epoxy masterbatch was used to prepare a series of nanocomposites with 5–25 wt% nanosilica content. Static uniaxial tensile tests were conducted to investigate the tensile stress–strain response and tensile properties of unmodified and nanomodified epoxy polymers. In addition, the degree of dispersion of the silica nanosphere particle in the epoxy matrix was investigated using transmission electron microscopy. It was found that the incorporation of a well-disperse nanosilica improved the tensile properties of the polymer. The addition of 25 wt% nanosilica enhanced the tensile modulus and strength of about 38% and 24%, respectively, compared to the neat polymer without sacrificing the failure strain