Abstract
Polymer blends of Poly (lactic acid) (PLA) and Polyethylene glycol (PEG) were obtained through reactive processing with maleic anhydride (MAH) and free radical initiators (POs) by simultaneous melt blending. The IR spectra of the polymer blends suggested the presence of graft copolymer, PLA-g-PEG. The effect of initiator concentration (MAH/PO ratio), residence time, reaction temperature and the free radical initiator species on grafting reaction was studied, and it was found that the polymer blend of PLA/PEG (90/10) (wt/wt) with MAH/dicumyl peroxide (DCP) (1.0/0.5) (phr/phr) at 180°C with higher residence time, gave more PLA-g-PEG product. However, the amount of the product decreased with increasing reaction temperature, with decreasing residence time. From the results of IR spectroscopy and size exclusion chromatography (SEC), the rate-determining step of this system would be additional reactions of MAH with PLA radicals, in the meanwhile, hydrogen abstraction reactions from PLA by DCP and additional reactions of PEG with maleated PLA can take place rapidly.
