Morphological evolution of block copolymer nanocomposites submitted to extensional flows

摘要: In this work, the effect of extensional flow on morphology polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS) triblock copolymers and their clay-containing nanocomposites was evaluated. Four types SEBS with different block compositions cylindrical were chosen to understand effects cylinder orientation state clay dispersion evolution during flow. The concentration (ranging from 2.5 7.5 wt. %) also studied. samples subjected using a Sentmanat rheometer attached rotational at Hencky strain rates varying 0.01 20 s−1. Small angle X-ray scattering analysis subsequently performed evaluate morphological changes caused by When preoriented [SEBS-30% PS (polystyrene)] undergo elongation, styrene cylinders nanoparticles align themselves in direction rheological behavior are influenced stretching (longitudinal transverse), rate magnitude, concentration, nanoparticles. isotropic (SEBS-13% PS) it observed that only exhibit structural alignment presence clay. Block copolymer molecules can relaxation times depending upon volume fraction domains (13% or 30%). addition clay, however, hinders complete relaxation, helping promote permanent domain after cessation, especially hard-to-align copolymers.