Maleic anhydride (MA) was grafted onto poly(lactic acid) (PLA) in the presence of styrene (St) by using a free-radical grafting methodology. The grafting degree (Dg) of MA was increased from 0.65 wt % to 1.1 wt % with the St/MA ratio up to 2/1, where the grafting efficiency (Eg) of MA was 27%. However, both Dg and Eg were decreased with further increasing of the St/MA ratio to 4/1. The Dg of MA...