Silica solid particles toughening,strengthening and anti-aging on epoxy resin

Solid particles used to toughen polymer can induce shear bands and crazing to release the internal stress of polymer. Herein, SiO₂ particles with different sizes were prepared by sol–gel method and modified by triethylenetetramine (TETA) in water. 1, 2, 3 and 4 wt% of SiO₂ and SiO₂-TETA particles are used to toughen epoxy resin (EP). They can form chemical bond with EP to heighten polymer^'s storage modulus and glass transition temperature. SiO₂-TETA containing active hydrogen atoms is a better cross-linking agent than SiO₂. Both SiO₂ and SiO₂-TETA particles possess obvious strengthening effects on EP. Their toughening effect depends on size. The 100 nm SiO₂ nanoparticles showed better toughening performance than 300 or 500 nm SiO₂ particles attributing to their higher specific surface area. The impact strength of EP/SiO₂-TETA composites with 3 wt% of 100 nm particles is 16.26 kJ/m², which is 27.67% and 8.00% higher than EP and EP/SiO₂ respectively. In addition, its tensile strength is 63.13 MPa, which is higher than the other is too. The barrier effect of solid particles can effectively improve the heat and ultraviolet resistant properties of EP matrix; as a result, their anti-aging property is improved significantly.