The effects of copolymerizing small amounts of an ionic moiety (0–7 mol %) into the backbone of a polycondensation polymer have been investigated by a combination of linear viscoelastic, steady‐shear, and extensional testing. At a constant viscosity in dilute solution, both the zero‐shear‐rate viscosity and the maximum relaxation time in the melt increase monotonically with an increase in the ionic character. These effects are present after the data are normalized to remove the increase in the glass transition temperature Tg with increased ionic content. Large‐strain, steady‐shear flow experiments showed that the viscoelastic memory of the melt is affected by ionic content. An increase in ion content causes a decrease in the effect of strain on the memory function. This effect is not apparent in extensional flow experiments, which indicate that the ionic content does not affect the response if the tests are conducted at a constant temperature above Tg.

SCOPEThe behavior of viscoelastic fluids in elongation is of extrusion, and certain coating and calendering operations. special importance in such industrial processes as fiber TO date, very little is known about the behavior of visco-'pinning, vacuum film elastic fluids in elongation. A particular void exists for Correspondence codcerning this paper should be addressed to Stanley fluids of moderate viscosity ( T~ -lo2 -lo4 P ) and at high

A versatile model for ε‐caprolactam polymerization is presented. A deterministic, mathematical basis for obtaining the most probable distribution of molecular weights in batch polymerization is developed. Continuous polycaproamide production has been modeled and shown to give othe than most probable distribution in many cases. The effect of adding monofunctional agents has been investigated. Results of some preliminary studies toward determining the optimal reactor configuration are presented.

This work describes a method of determining the limits of uniform extensibility, in terms of failure and fracture, from rheological tests in extensional flow. The limit of uniform stretching can be expressed in terms of the Weissenberg number for the process, as demonstrated by data for three chemically diverse polymers, polystyrene, poly(methyl methacrylate), and a polyester. The BKZ‐K model can be used to predict necking failure, as determined by the Considére criterion, and an empirical correlation can be derived for fracture.

SynopsisThis work describes a method of determining the limits of uniform extensibility, in terms of failure and fracture, from rheological tests in extensional flow. The limit of uniform stretching can be expressed in terms of the Weissenberg number for the process, as demonstrated by data for three chemically diverse polymers, polystyrene, poly(methy1 methacrylate), and a polyester. The BKZK model can be used to predict necking failure, as determined by the Considere criterion, and an empirical correlation can be derived for fracture.