Five kinds of blends: polyacetal (POM) and polytetrafluoroethylenes (PTFEs) [pure (PTFE), coupling agent coated (LZ-PTFE), chemical-treated (CPTFE, containing NaF salt), chemical-treated (WPTFE, no NaF salt), coupling agent coated WPTFE(LZ-WPTFE)] were prepared by mechanical blending. The PTFE presented in the blends, had good wear resistance properties. However, the adhesion interaction between the POM and the PTFE was poor, and increasing the PTFE content caused a decrease in the mechanical properties. Using the chemical surface treatment method to etch PTFE could cause treated-PTFE to homogeneously disperse in POM. This result caused the POM/treated-PTFE blends to have higher mechanical properties than those of the POM/PTFE blends. The NaF salt that adsorbed on the CPTFE surface acted as a coupling agent and offered a very strong adhesion interaction between the POM and the CPTFE. The free salt also acted as a nuclei to aid POM in crystallizing. As a result, the POM/CPTFE blends possessed the highest mechanical properties of all the blends and the best wear resistance property of POM/modified-PTFE(LZ-PTFE, LZ-WPTFE, WPTFE, CPTFE) blends. © 1993 John Wiley & Sons, Inc.