or hydrogen bonding causing increase in the apparent viscos-
ity. For DCPEA/PMA blends,
Fig. 1
(c), containing 70%
PMA the apparent viscosity decreases as the shear rate in-
creases. Beyond 30 s
1
shear rate the curve shows a linear
behaviour but deviates from the Newtonian behaviour of con-
stant viscosity at various shear rates. Similar behaviour is ob-
served for blends containing 60% PMA and 50% PMA.
However an opposite behaviour is observed for the blend con-
taining 30% PMA. In this case, the apparent viscosity in-
creases and becomes constant. In the above composition of
the blend, phase inversion occurs which causes a change in
the apparent viscosity behaviour from pseudoplastic to a dilat-
ant type fluid. The blend of composition 20% PMA, also
shows similar behaviour. The linear portion of the curves from
composition containing 70–40% PMA shows slight negative
deviation from the Newtonian fluid behaviour. This behaviour
along with phase inversion indicates the immiscibility of the
components of the blends. The viscosity–composition curve
also shows a phase inversion at 40% PMA,
Fig. 2
(c). The
blends of LOPEA/PMA,
Fig. 1
(d), show pseudo-plastic behav-
iour with the increase in the shear shear rate which indicates
that under increasing shear stress the blend aggregates undergo
loosening of the structure and conformational changes which
bring about lowering of the viscosity. For the composition LO-
PEA/PMA containing 30% PMA, the apparent viscosity is
higher than the blends containing 40% PMA and 50% PMA
and has lower viscosity than blends containing 60% PMA
and 80% PMA. This clearly shows phase inversion at 40%
PMA indicating incompatibility of the components. The vis-
cosity–composition curve also indicates phase inversion at this
composition and corroborates the inference from the rheolog-
ical measurements,
Fig. 2
(d)