Mechanical properties of potassium titanate whiskers reinforced poly(ether ether ketone) composites using different compounding processes

The composites of poly(ether ether ketone) (PEEK) reinforced with potassium titanate whiskers (PTW) were prepared through pre-compounding by twin-screw extruder or two-roller torque rheometer, and then injection molding. The tensile and impact properties of the composites were investigated and the fracture morphologies were observed. Length distributions of PTW in the injection molded composite specimens were measured. The orientation distributions of PTW on the cross sections parallel to the melt flow direction were observed. The tensile test results verified the reinforcement effect of PTW on the mechanical properties of PEEK resin. The tensile strength and the tensile modulus of the composites increased with the increasing PTW content within the used loading range till 30 wt%. It is revealed that the compounding processes exhibited great influence on the reinforcement efficiency of PTW. The composites pre-compounded with the rheometer possessed higher mechanical performance than those pre-compounded with the extruder. The observations on length and orientation distributions of PTW showed that using rheometer can result in larger residual length of PTW and higher orientation factor in the composites along melt flow direction, to which the enhancements in the mechanical properties of the composites pre-compounded with the rheometer were attributed.