Influence of molecular structure on pressure and temperature dependent viscosity of LDPE melts

Abstract

A capillary rheometer equipped with an especially designed additional chamber ensuring various pressure modes was used to investigate temperature and pressure effects on the Theological properties of two batches of the same LDPE grade. The variation in molecular structure of the researched batches was proved by different gel permeation chromatography and elongational viscosity behavior. The magnitudes of the pressure coefficients varied more significantly than temperature ones. I.e. the pressure effect on viscosity depends strongly on the amount of long-chain branching in polymer.