5. Results and discussion
5.1. Rheological measurements of blends
The apparent viscosity of 8% solution of DCOE/PMA and
LOE/PMA blends at various shear rates is shown in
Fig. 1
(a) and (b). The figures show that as the shear rate is in-
creased, the apparent viscosity initially increases and becomes
constant at 20 s
1
indicating that conformation of the polymer
blend agglomerate becomes more or less stable and slightly
changes with the increasing shear shear rate. This behaviour
is also observed for pristine PMA, DCOE and LOE. At higher
shear rates, all blend compositions of the system show positive
deviation from Newtonian behaviour which can be attributed
to the slight incompatibility of the blend components in the
solution phase at this concentration. The viscometric studies
at 8% of the blends at various compositions also reveal slight
incompatibility in the viscosity–composition curves,
Fig. 2
(a)
and (b). We attribute this to some conformational changes in
the polymer blend aggregates. The increase in the apparent vis-
cosity at increasing shear rates or stress shows that under
increasing shear stress, the layers of the solution are com-
pressed as they move past each other. As a result the molecules
come closer and get entangled through electrostatic interaction