We showed that a highly fibrillar s

We showed that a highly fibrillar structure is obtained, along with good mechanical properties, above a cer­ tain draw ratio. This limit was as low as five with a100 m spinneret.Other work has been done in this field. Dube and Blackwell3 studied the effect of precipitation con­ ditions, solution composition, and drying conditions on the structure of the fibers. Navard and Haudin4 looked mainly at the effect of draw ratio (DR), show­ ing the presence of draw resonance above a DR of 55. Quenin5 looked at various parameters such as the type of amine oxide used as a solvent. The patent literature6-8 covers the fact that an air gap must be used in the process. Other work has been done by Taeger et al.9 and Simon.10 None of this work has looked in detail at how the air gap affects the for­ mation of the fiber. The air gap is an important part of the process because it allows the drawing of the fiber to the desired linear density (dtex) and the orientation of the polymer to impart it with good mechanical properties, which makes poststretching unnecessary. It also allows the simultaneous use of a spinneret above 90°C and a coagulation bath at a different temperature.