The effect of distilled water, methanol, ethanol, acetone and cosolvent (comprising ethanol and distilled water, the volume fraction of ethanol in the cosolvent was 10V(f)% and 20V(f)%) on the friction welding properties between parts of PMMA with PVC is investigated. Treatment with those solvents, 20V(f)% cosolvent and 10V(f)% cosolvent promote about 360%, 280% and 110% more bonding strength than without any solvent treatment. The tensile fracture morphology of welded PMMA with PVC has three zones: the non-plasticized central zone (Fud), the plasticized peripheral zone (Fpl), and the partly plasticized zone between Fud and Fpl (Fpd). Comparing tensile fracture morphology and residual solvent with bonding strength, it has larger Fpd regions, no Fud in the central part and less residual solvent is responsible for better bonding strength. (C) 2003 Kluwer Academic Publishers.