Poly(Ether/Ester)s based on poly(tetramethylene terephthalate) and poly(ethylene glycol), 3. Effect of thermal treatment and drawing on the structure of the poly(ether/ester)s

Annealed drawn and undrawn bristles of poly(ether/ester)s based on poly(tetramethylene terephthalate) (PTMT) and poly(ethylene glycol) PEG 1000 (in various ratios) are studied by means of small‐angle X‐ray scatering and differential scanning calorimetry (DSC). The samples with the lowest PTMT content (49 wt.‐% PTMT) show on abrupt increase of the scattering intensity and the long spacing with increasing annealing temperature T a , this increase becoming less pronounced with increasing fraction of hard segment (PTMT). The DSC heating scans are characterized by a low‐temperature glass transition due to the soft polyether segments and a multiple melting behaviour at about 200°C due to the crystalline hard PTMT segments. The data suggest a dependence of the thermal behaviour on the chemical composition, annealing temperature, and orientation. The characteristics of the undrawn samples are similar to those of the homopolyester PTMT and the copolymers based on PTMT and poly(tetramethylene oxide). Evidence is found for an increase of phase separation with an increase of the annealing temperature. The formation of larger amorphous regions of PEG with increasing T a determines the thermal and scattering behaviour observed.