Characterization of the coagulation process: wet-spinning tool development and void fraction evaluation

Since very little research has been published on the wet-spinning process, this article is a contribution to understanding the coagulation phenomenon. In this work, the effects of spinning parameters on the evolution of the void fraction of coarse polyamide-imide monofilaments were investigated. First of all, an experimental wet-spinning device was designed in our laboratory. Robust and reliable, this prototyping tool allows a fully automated production, ensuring the reproducibility of the different spinning tests. A four-factor Design of Experiments was built to analyze the effects and combinations between the following parameters: extrusion diameter, concentration of the coagulation bath and drawing rates applied in the coagulation bath and in the air. The results derived from a statistical analysis coupled to a scanning electron microscope study showed a highly significant influence of the concentration of solvent in the coagulation bath, concerning the evolution of the void fraction of the obtained monofilaments.