DYNAMIC VISCOELASTIC BEHAVIOR OF POLY ETHER-POLYESTER BLOCK COPOLYMERS

Abstract

The dynamic viscoelastic behavior of linear segmented polyether-polyester block copolymers prepared by polycondensation was investigated. Polyethylene-1, 2-diphenoxyethanc-p, p'-dicarboxylate (B) and polyethylene-terephthalate (T) were used as the hard segments of block copolymers, while polyethylene glycol (E) and polyoxybutylene glycol (G) as soft segments.The temperature dependences of storage modulus E', loss modulus E'' and loss tangent (tan δ) for block copolymers were measured at 10 Mz by Spectrometer.The results are summarized as follows:(1) The peak of tan δ of B-E 1540 block copolymer was observed at about -30°C, and E' at rubberlike region were in the order of about 108 dyne/cm2.(2) With the increase of polyester content, the lowering of E' with increasing temperature became small and tan δmax shifted toward high temperature region.(3) As the molecular weight of polyether increased, the peak of tan δ became broad and the lowering of E' became small due to the crystallization of polyether, and the values of E' decreased remarkably at the melting temperature of polyether segment.(4) When the hard segment B was replaced by hard segment T, the tan δmax in T-E1540 was observed in somewhat lower temperature with higher peak intensity than that of B-E1540.(5) By replacing soft segment E with hard segment G, the tan δmax of B-G1000 shifted to the lower temperature and displayed somewhat broader shape than that of B-E1540.On the bases of these results, the effects of hard segments on the mobility of soft segments and the intermolecular attraction between soft and hard segment-domains are discussed.