On the measurement of viscosity overshot of elongational viscosity of LDPE

The presence of long side chains in LDPE molecule leads to the rise of uniaxial viscosity above trouton ratio in uniaxial elongational flow. In this paper the dynamic oscillatory tests at 3 different temperatures used for evaluating the time-temperature superposition. All dynamic moduli shifted to the reference temperature of 160 oC. The superimposed data showed that the time-temperature superposition principle holds for the studied LDPE. The strain hardening behavior of LDPE studied in unidirectional flow, by a home-made SER fixture, at different strain rates