Authors Weidisch, R. ; Schreyeck, G. ; Ensslen, M. ; Michler, G.H. ; Stamm, M. ; Schubert, D.W. ; Budde, H. ; Höring, S. ; Arnold, M. ; Jérome, R.
Title Deformation Behavior of Weakly Segregated Block Copolymers. 2. Correlation between Phase Behavior and Deformation Mechanisms of Diblock Copolymers
Date 10.08.2000
Number 9309
Abstract The deformation behavior of poly(styrene-<I>b</I>-butyl methacrylate) diblock copolymers, PS-<I>b</I>-PBMA, is studied by high-voltage electron microscopy (HVEM) with an in-situ tensile device. While inthe first part the phase behavior of PS-<I>b</I>-PBMA diblock copolymers is investigated via small-angle neutronscattering (SANS), in the second part the deformation behavior depending on composition and molecularweight is discussed. Disordered block copolymers have the same deformation mechanism as thecorresponding homopolymers, while microphase-separated block copolymers undergo a cavitationmechanism. At the order-disorder transition, ODT, a transition from crazing to cavitation mechanismis fou<br />nd via HVEM. Moreover, a sharp increase of the diameter of craze fibrils occurs at the ODT,demonstrating that the craze microstructure is strongly influenced by phase behavior. As the incompatibility increases with increasing molecular weight, deformation mechanisms such as diversion andtermination of crazes are observed for intermediately segregated block copolymers. The discussedcorrelation between phase behavior and deformation mechanisms indicates the existence of a unifiedscheme for deformation behavior of diblock copolymers depending on the strength of segregation, <IMG SRC="/images/gifchars/chi.gif" BORDER=0 ><I>N</I>.
Publisher Macromolecules
Citation Macromolecules 33 (2000) 5495-5504
Tags - order-disorder transition tensile properties morphology methacrylate) polystyrene temperature blends thermodynamics dependence melt

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