The effect of branchings in polycarbonates on their molten-state viscosity
Molten-state viscosity of samples of branched bisphe- nol-A polycarbonate has been measured at 280°C in relation to shear rate, γ. Zero-shear rate viscosity, ηo has been determined and the universal flow curves log ηo/ ηo = f(log γ. ηo) plotted. It has been found that branchings in polycarbonate macromolecules influence the course of those curves and thus linear polycarbonate can be distinguished from branched one. The dependence of ho on the weight-average molecular mass, Mw, degree of polymolecularity and degree of branching has been given. It has also been found that by the selection of an appropriate branching agent and its amount it is possible to modify correspondingly the processing properties of polycarbonates.
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