A Collaborative Study of the Rheological Properties And Unstable Melt Spinning Characteristics Of Linear And Branched Polyethylene Terephthalates

Abstract

A comparative study by several industrial and academic laboratories of the rheological properties and melt spinning behavior of a series of molecularly characterized linear and a branched polyethylene terephthalate is reported. Steady shear viscosity, normal stresses, dynamic sinusoidal behavior, and capillary entrance elongational flow behavior are reported. The branched melt has a lower shear and dynamic viscosity (at the same molecular weight), a higher steady state compliance and principal normal stress difference (at the same shear stress). The elong-ational viscosity of the branched sample seems to be increasing with tensile stress. The branched sample exhibits much greater spinline stability than the linear polyester. The results of different laboratories are compared. Printed in Great Britain. © 1985 IUPAC