Studies on Melt Spinning. I. Effect of Molecular Structure and Molecular Weight Distribution on Elongational Viscosity

Abstract

A melt spinning experiment has been carried out to correlate spinning variables with the molecular weight, molecular weight distribution, and long chain branching of the polymer being spun. Materials chosen for study were three high density polyethylenes having widely different molecular weight distributions, a low density polyethylene having much long chain branching, a polystyrene, and a polypropylene. Molecular characteristics and rheological properties of the materials in simple shearing flow had been independently determined. For the study, a bench scale, melt spinning apparatus was built, and measurements were taken of thread tensions at the take‐up device. The axial profiles of thread diameter were measured by a photographic technique. The molten fibers traveled through a heated chamber maintained at the same temperature as the melt. These measurements were then used to determine the elongational viscosity in the absence of any temperature effect.