DYNAMIC VISCOELASTIC PROPERTIES OF POLY(ETHYLENE-PROPYLENE) DIBLOCK COPOLYMER IN THE MELT STATE AND SOLUTIONS

Dynamic mechanical properties of a symmetrical poly(ethylene-propylene ) diblock copolymer with a molecular weight of 99 x 10(3) were investi gated in the melt state, as well as in solutions in 1,2,4-trichloroben zene. In the melt state, the frequency dependence of the elastic and l oss moduli (G' and G'', respectively) exhibited a limiting behaviour o f G' approximate to G '' approximate to omega(0.5) in the terminal zon e, a marker of inhomogeneity. Even solutions of 15 vol% polymer showed such inhomogeneity. These theological data indicate that the diblock polymer is microphase separated and the phases are strongly segregated . The limiting behaviour in the terminal zone suggests that a lamellar structure is present in the melt. Copyright (C) 1996 Elsevier Science Ltd.