Investigation on the mechanical performances of ternary nylon 6/SEBS elastomer/nano-SiO₂ hybrid composites with controlled morphology

The distribution of maleated styrene-hydrogenated butadiene-styrene (mSEBS) elastomer and nano-SiO₂ in nylon 6 matrix was controlled by varying the blending procedure. Nano-SiO₂ particles with different surface properties (hydrophilic versus hydrophobic) were adopted to adjust their interactions with other components. Two different structures, separate dispersion of nano-SiO₂ and elastomer particles as well as encapsulation of nano-SiO₂ fillers by the elastomer, were obtained. The structures were confirmed through scanning electron microscope (SEM) investigation. The mechanical measurement results showed that the microstructure and the interactions among the components had dramatic influences on the final mechanical properties, especially Izod fracture toughness, for the ternary nanocomposites. The nanocomposites containing hydrophilic nano-SiO₂ had better mechanical performances compared with the composites filled with hydrophobic SiO₂ when they were in the same microstructure. The nanocomposites with separate dispersion structure showed higher stiffness compared with those of encapsulation type. However, the separately dispersed nano-SiO₂ particles restricted the cavitation of elastomer phases that led to low toughening effectiveness. The difference of cavitation intensity for elastomer phase was revealed by SEM investigation on the facture surfaces for the nanocomposites with the two different microstructures.