Effect of the oxidation progress of tributylborane on the grafting reaction of PMMA onto high-density polyethylene (HDPE) and isotropic polypropylene (iPP) surface with tributylborane as initiator was studied in detail. The oxidation of tributylborane was triggered by the slow diffused oxygen or exposed contact to oxygen, so that the oxidation progress of tributylborane would be different. The grafted polyolefin surfaces were characterized by attenuated total reflection infrared (ATR-IR) spectroscopy, X-ray photoelectron spectroscopic (XPS), scanning electron microscope (SEM) and so on. The results of ATR-IR spectroscopy and XPS analysis suggested that PMMA could be grafted onto polyolefin surfaces successfully through these two ways, but the grafting degrees were varied due to the different oxidation progresses of tributylborane. The surface morphologies of the polyolefin indicated the different grafting degrees as a result of different oxidation progress of tributylborane. (C) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012