The improvement in cryogenic mechanical properties of nano-ZrO2/epoxy composites via surface modification of nano-ZrO2

This study investigated the cryogenic mechanical properties of modified nano-ZrO2 reinforced epoxy composites. Nano-ZrO2 was surface modified by (3-aminopropyl)triethoxysilane (APTES) and results of Fourier transform infrared spectroscopy (FTIR) verified that APTES was successfully grafted onto the surface of nano-ZrO2. Transmission electron microscopy (TEM) observations indicated that APTES modification was favorable to the dispersion of nano-ZrO2 in an epoxy matrix. Glass transition temperatures of the modified nano-ZrO2/epoxy composites were also improved compared with those of the neat epoxy resin and the unmodified nano-ZrO2/epoxy composite. Results of the mechanical tests showed that the modified nano-ZrO2 could improve the mechanical properties of the epoxy composites more effectively than unmodified ones. Tensile strength and failure strain of the modified nano-ZrO2/epoxy composites were at most increased by 30.2% and 49.7% at room temperature (RT), while their highest enhancements at 90 K were 26.4% and 21.1%, respectively, compared with those of the neat epoxy resin. Besides, fracture toughness at RT and 90 K were at most increased by 53.3% and 39.4%, respectively. These enhancements were mainly attributed to the strong modified nano-ZrO2/epoxy interfacial bonding and the better dispersion of the modified nano-ZrO2 in the epoxy matrix. Summarily, it could be concluded that APTES modified nano-ZrO2 is a promising filler for enhancing cryogenic mechanical properties of epoxy resins.