Rheological characteristics and morphologies of styrene–butadiene–maleic anhydride block copolymers

Studies on the morphologies and rheological characteristics of two styrene–butadiene–maleic anhydride block copolymers (SBMa) have been performed. The transmission electron microscopy micrographs show that the morphologies of SBMa change from matrix–island structure to co-continuous structure. Curves for dynamic modulus varied with frequency (ω) show obvious solid-like behavior in the low ω region, which is typical for ordered block copolymers or networked materials. Van Gurp–Palmen plots have been used to exploit the thermorheological complexity of two copolymers. The master curves of two copolymers have been acquired through time–temperature superposition principle, and the plateau modulus (G) have been obtained from G′ at ω, where the loss tangent (tan δ) approaches a minimum. Meanwhile, Williams–Landel–Ferry equation has been used to evaluate the free volume parameters. The relaxation time spectra of two copolymers have been calculated and fitted with modified Baumgaertel–Schausberger–Winter model. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012