Enhanced dynamic mechanical and shape-memory properties of a poly(ethyleneterephthalate)-poly(ethylene glycol) copolymer crosslinked by maleic anhydride

Dimethyl terephthalate (DMT) and ethylene glycol (EG) were used for the pre paration of poly(ethylene terephthalate) (PET), and poly(ethylene glycol) ( PEG) was added as a soft segment to prepare a PET-PEG copolymer with a shap e-memory function. MWs of the PEG used were 200, 400, 600, and 1000 g/mol, and various molar ratios of EG and PEG were tried. Their tensile and shape- memory properties were compared at various points. The glass-transition and melting temperatures of PET-PEG copolymers decreased with increasing PEG m olecular weight and content. A tensile test showed that the most ideal mech anical properties were obtained when the molar ratio of EG and PEG was set to 80:20 with 200 g/mol of PEG. The shape memory of the copolymer with male ic anhydride (MAH) as a crosslinking agent was also tested in terms of shap e retention and shape recovery rate. The amount of MAH added was between 0. 5 and 2.5 mol % with respect to DMT, and tensile properties and shape reten tion and recovery rate generally improved with increasing MAH. (C) 2002 Joh n Wiley & Sons, Inc.