Enhanced mechanical and tribological performance of PA66 nanocomposites containing 2D layered α-zirconium phosphate nanoplatelets with different sizes

Two-dimensional layered α-zirconium phosphate (ZrP) nanoplatelets with two distinguished sizes but similar aspect ratio were directly incorporated into polyamide 66 (PA66) by simple melt processing without using any surfactants. Through the electron microscopy analysis, the large ZrP nanoplatelets with ~ 1.33 μm in size and ~ 5.8 in aspect ratio exhibit a uniform dispersion in PA66 matrices at the filler loading up to 3 wt%, while the small ZrP nanoplatelets with an average size of ~ 230 nm and aspect ratio of ~ 6.2 tend to form large-scale aggregates in PA66 even at 1 wt% loading. Tensile testing results illustrate that the large ZrP nanoplatelets exhibit a better reinforcement effect in PA66 than the small ones. With the incorporation of 3 wt% large ZrP nanoplatelets, the PA66 nanocomposites exhibit an increase of ~ 10% in tensile modulus and ~ 14% in tensile strength as compared with the pure PA66. Pin-on-disc wear tests illustrate that the nanocomposites containing large ZrP nanoplatelets have better anti-wear properties than those prepared with small ZrP nanoplatelets. In specific, the PA66 nanocomposites containing 1 wt% large ZrP nanoplatelets show a ~ 43% decrease in friction coefficient and a ~ 59% reduction in the wear rate under the test condition of 40 N in load and 0.6 m/s in velocity. The mechanisms that are responsible for the mechanical and tribological enhancements in the PA66/ZrP nanocomposites have also been discussed.