Phase Behavior of Poly(butylene terephthalate)/Polyarylate Blends

In the present paper, we explore the amorphous phase behavior of poly(butylene terephthalate) (PBT)/polyarylate (PAr) blends, primarily using dielectric spectroscopy. Small-angle X-ray scattering experiments show clearly that the PAr resides in the interlamellar zones. We observe two dielectric relaxations associated with long-range motion for blends in which PBT has crystallized. Following from recent research on order-disorder interphases in crystalline blends, we tentatively assign the low-temperature transition to the presence of a crystal-amorphous interphase and the high-temperature relaxation to an unconstrained (mixed) amorphous phase.