Morphological changes which are induced in poly(urethane-ester)by annealing and quenching are studied using DSC analysis technique. The samples used in this study are polyether polyurethane elastomers based on either MDI/BHET or MDI/BHET-D hard segments combined with PTMO (Mw=1000) as soft segment
and hard segment homopolymers of MDI/BHET and MDI/BHET-D.DSC measurements taken immediately after the quench show that the soft segment Tg is higher than that of the control
suggesting that the applied thermal history promoted increasing mixing of hard and soft segments. Three endotherms are observed in untreated sample at ligh temperature range.They are attributed to short-range
long-range and microcrystaline ordering of hard segment domains.