Phase Demixing
Chemical transformation demixes a homogeneous polymer solution into liquid-rich and solid-rich phases to form porous membrane structures. Controlled phase inversion transforms liquid polyurethane or synthetic resin formulations into solid micro-porous coatings when exposed to anti-solvent baths or controlled evaporation. The mechanism dictates pore morphology in functional outerwear membranes.
Coagulation Process
Submerging a polymer-coated textile web into a water coagulation bath initiates rapid mass transfer between organic solvent and non-solvent water molecules. As water diffuses into the polymer solution, solvent diffuses out into the water bath, forcing local polymer concentration above saturation limits. Nucleation and growth of polymer-lean liquid droplets create void networks, while the polymer-rich phase solidifies into structural cell walls.
Adjusting bath temperature, solvent ratios, and immersion time controls pore size, surface skin density, and overall membrane permeability.
Process Boundary
Thermal melting and mechanical stretching processes do not involve chemical phase separation mechanisms. Phase inversion applies specifically to wet-processed solution polymer systems rather than thermoplastic extruded films.
Quality Checkpoint
Mill engineers monitor bath solvent concentrations and temperature profiles to maintain consistent membrane porosity across production runs. Flaws in phase separation cause non-uniform pore distributions that result in localized water leakage. Membrane pore structures undergo scanning electron microscopy inspection to verify structural consistency.
