K2Ti6O13 whisker was modified with n-octadecyltrichlorosilane (OTS), fluorosurfactant (FSK), and silane coupling agent (KH-550), respectively. The surface energy of K2Ti6O13 whisker was calculated based on Van Oss-Chaudhury-Good function. Then the influence of surface modification on the tribological and mechanical properties of K2Ti6O13 whisker filled polytetrafluoroethylene (PTFE) composites was studied. Surface energy calculation shows that the surface energy of OTS-treated K2Ti6O13 whisker is only 29.0 mJ/m(2), which is the closest to the value of pure PTFE. Among all samples, the PTFE composite filled with OTS-treated K2Ti6O13 whisker shows the best antiwear property, tensile strength, and impact strength, which is about 19 to 33%, 15 and 55% higher than that of untreated K2Ti6O13 whisker filled PTFE, respectively. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012