M. Astruc et P. Navard, A flow-induced phase inversion in immiscible polymer blends containing a liquid-crystalline polymer studied by in situ optical microscopy, J RHEOL, 44(4), 2000, pp. 693-712
The phase inversion from a morphology of hydroxypropylcellulose in water (H
PC50%) droplets in polydimethylsiloxane (PDMS) matrix to a morphology of PD
MS droplets in HPC50% matrix can be induced by a change of shear rate, due
to a viscosity ratio inversion. Such a process passing through four differe
nt transient morphological stages was studied by optical microscopy in a tr
ansparent shear device. In a certain concentration region, at a fixed shear
rate, after sheets of PDMS were formed, the transition "hesitates" between
phase inversion and refined starting morphology. The influence of PDMS con
centration, shear rate, elasticity, and phase dimension on the final morpho
logy was investigated and compared with different models given in the liter
ature. The influence of concentration and shear rate on the duration of the
transient flow was also studied. We propose a simplified model of breakage
of filaments to explain a part of our results. (C) 2000 The Society of Rhe
ology. [S0148-6055(00)01504-2].