Rheological behaviour of thermoplastic elastomers from polypropylene/acrylonitrile-butadiene rubber blends: effect of blend ratio, reactive compatibilization and dynamic vulcanization
S. George et al., Rheological behaviour of thermoplastic elastomers from polypropylene/acrylonitrile-butadiene rubber blends: effect of blend ratio, reactive compatibilization and dynamic vulcanization, POLYMER, 40(15), 1999, pp. 4325-4344
The rheological behaviour of polypropylene (PP)/acrylonitrile-butadiene rub
ber (NBR) blends has been investigated with special reference to the effect
of blend ratio, compatibilization and dynamic vulcanization. The morpholog
y of the extrudates and the size and distribution of domains were examined,
PP/NBR blends show pseudoplastic behaviour, which is evidenced by the decr
ease in viscosity with increasing shear rate. The melt viscosity of these b
lends increased with increasing nitrile rubber concentration and shows nega
tive deviation from the theoretically predicted values. Compatibilization o
f the blends with phenolic-modified polypropylene (Ph-PP) increases the mel
t viscosity at low concentrations of Ph-PP. The rheological behaviour of PP
/BR blends was correlated with the blend morphology. Dynamic vulcanization
has a decreasing effect on die swell values. The effect of temperature on t
he melt viscosity of the blends was examined and attempts have been made to
construct a shear rate-temperature superposition master curve. The melt-fl
ow index values for these blends were measured and have been correlated wit
h rheometer data to develop a master curve for different blend compositions
. The morphological analysis indicates that compatibilization of the blends
prevents the coalescence of dispersed NBR domains during annealing. (C) 19
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