Solvent Exchange
Polymer precipitation method used to form solid fibers or coatings by immersing a polymer solution into a non-solvent bath. Wet coagulation is the primary technique for producing synthetic leathers and certain types of high strength rayon fibers. The boundary of the process is the point where the polymer has completely solidified and the solvent has been washed away.
Pore Formation
Immersion in the bath causes the solvent to leave the polymer and enter the water, which triggers the solidification of the resin. During wet coagulation, the speed of this exchange determines the density and the mechanical strength of the resulting material.
Coating Thickness
Small gaps are left behind as the liquid leaves the solidifying structure. If wet coagulation is performed too quickly, the material may develop large internal voids that lead to a weak and brittle finish.
Structural Boundary
Total control over the temperature and the chemistry of the coagulation bath is required to produce a consistent product. Adjusting the concentration of the initial polymer dope allows for the creation of layers with specific weights and textures. Modern factories use automated systems to monitor the solvent concentration and ensure that the bath remains effective throughout the production day.
The process is fundamental to the creation of durable and breathable synthetic materials for the footwear industry.
