Dynamic mechanical properties of segmented polyester-ether elastomers were determined by the viscoelastic spectroscopy.
Poly (ethyleneterephthalate) [T] and poly (ethyleneterephthalate-coisophthalate) [T/iPh] were used as the hard segments, while poly (ethyleneglycol) [E], poly (tetramethyleneglycol) [G] and their blended polyethers [E/G] as the soft segments.
Temperature dependence of elastomers composed of varying species of polyether as the soft segment on the dynamic modulus
E′ and on the loss tangent (tan δ) was discussed. Effects of variations in the soft segment concentration and in its molecular weight on
E′ and tan δ were also investigated.
A single loss peak due to the glass transition occurring in the non-crystalline phase consisting of a mixture of soft and hard segments was observed in T-E elastomers because of good compatibility of E with the hard segment. While, for T-G, especially in the case of hard-soft weight ratio was 50:50, two broad and weak peaks were observed separately in high and low temperature regions, indicating the improvement of the phase segregation between hard and soft segments.
The decrease in the loss peak area and the rise of the dynamic modulus in transition region suggested the crystallization of the soft segment of molecular weight 1500 or above.
Incorporation of iPh sequences in T-E elastomer improved the mixing of extended hard segment with the soft segment phase, which enhances the interaction between soft and hard segments.
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