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An experimental study of threadline dynamics with emphasis on the effect of molecular weight on the elongational viscosity of melt‐spun poly(ethylene terephthalate)
Author(s) -
Hill Jack W.,
Cuculo John A.
Publication year - 1974
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1974.070180902
Subject(s) - elongation , viscosity , materials science , polymer , surface tension , thermodynamics , polymer chemistry , composite material , ultimate tensile strength , physics
A study of a melt‐spun threadline has been carried out to determine the effect of molecular weight on the elongational viscosity of the polymer being spun. Polymer chosen for this study was poly(ethylene terephthalate) having different molecular weights. Conventional nonisothermal spinning of the polymers was carried out with cooling by free convection. Threadline surface temperatures were measured by a null‐balance technique. Threadline tension at the take‐up device was measured, and samples of the threadline were taken to obtain linear density profiles. Nonlinear least‐squares fits were applied to the linear density data to obtain equations for velocity and elongation rate. These measurements were then used to determine the threadline elongational viscosity. Least‐squares fits were made to a polynomial relating absolute temperature and elongation rate to the elengational viscosity. These results were then used to determine an activation energy of elongational flow which was found to decrease with elongation rate. Elongational viscosity was found to increase with molecular weight.