Polylactide (PLA)/poly(ethylene oxide) (PEO) blends were prepared by melt-mixing

and the influence of molecular weight of PEO on the thermal-mechanical properties and rheological behaviors of the blends was investigated.Four kinds of PEO with molecular weight of 2 kDa (PEG2)

10 kDa (PEG10)

100 kDa (PEO100) and 600 kDa (PEO600) were used in this study.It was found that all PEOs were miscible with PLA to an extent of ca. 20 wt% and their quenched blends were completely amorphous.The decrease of Tgshowed the plasticization effect of PEO on PLA.When the molecular weight of PEO was over 10 kDa

the plasticization effect was not dependence on the molecular weight of PEO

which did not decrease with the increase of molecular weight of PEO.Increasing the molecular weight of PEO can increase the tensile modulus and melt intensity of PLA/PEO blends

while the ductility of the blends was not decreased.All blends with 20 wt% PEO had a similar elongation at break of about 330%

but tensile moldulus of the blends changed from 250 MPa for the PLA/PEG2 blend to 550 MPa for the PLA/PEO600 blend.The rheology experiments indicated the G′increased significantly with the increase of molecular weight of PEO for the blends with same composition.