Effect of nano TiO 2 particle size on mechanical properties of cured epoxy resin

Abstract

Mechanical properties of toughened epoxy resin with two nano particles sizes of TiO 2 (17 nm and 50 nm) at different weight fractions (1%, 3%, 5% and 10%) were investigated and compared to that of submicron particles at 220 nm. The composites were characterized by tensile, flexural, pull-off and abrasion tests, followed by X-ray photoelectron spectroscopy and scanning electron microscopy of the fracture surfaces. The investigated epoxy depicted high performance epoxy systems formulated with low molecular weight epoxy resin and diethyltoluenediamine as a curing agent. Results indicate an enhancement in the epoxy composite mechanical properties due to the addition of small fraction of TiO 2 particles. Highest tensile stress values were found at 3 wt.% for 17 nm and 50 nm particles and at 5 wt.% for 220 nm particles. The maximum flexural properties were found at lower TiO 2 fraction of 1 wt.% only. The flexural behavior of the epoxy composite was not improved by further addition of the filler. The enhancement of modified epoxy with the smaller nano particles size showed a better resistance to weight loss. It is suggested that the amount of particles present and its size affect the matrix deformation and as a result, the quality of interface in the composite. A relation between tensile and flexural stress as function of the toughened particle size was found.