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Phase Inversion of Polybutadiene/Polyisoprene Blends Under Quiescent and Shear Conditions



H Jeon, A Nakatani, Erik K. Hobbie, Charles C. Han


We investigate the effect of phase inversion on the domain morphology and rheological properties of phase-separated polybutadiene/polyisoprene blends using optical microscopy, light scattering, and rheometry. Two different blends, low-vinyl polybutadiene/low-vinyl polyisoprene (LPB/LPI) and low-vinyl polybutadiene/high-vinyl polyisoprene (LPB/HPI), were used in this study. The LPB/LPI blend has a lower critical solution temperature (LCST) of (62 1) C, while the LPB/HPI blend exhibits upper-critical-solution-temperature (UCST) behavior with a critical temperature above the experimentally accessible temperature window. We determine the quiescent phase-inversion composition (fLPI = 0.55 0.05) of phase-separated LPB/LPI blends from the discontinuity in the dynamic storage modulus and shear viscosity. For LPB/HPI, we find that a coexisting structure (apparent as a walnut-like light-scattering pattern) develops due to a shear-induced phase inversion at a fixed composition (fHPI = 0.8) and constant temperature. The coexisting morphology consists of two different anisotropic structures; string-like domains and small (x < 1 mm) vorticity-aligned domains.


emulsions, light scattering, microscopy, phase inversion, polymer blends, shear flow


Jeon, H. , Nakatani, A. , Hobbie, E. and Han, C. (2001), Phase Inversion of Polybutadiene/Polyisoprene Blends Under Quiescent and Shear Conditions, Langmuir, [online], (Accessed May 17, 2024)


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Created January 1, 2001, Updated February 19, 2017