Extruded material is stretched under various temperatures to generate pore population and respective pore size to provide specific porosity (open area). This stretch process includes a reasonable relaxing of material stretch to minimize shrinkage of final product.
The basic principle is similar for both the production of flat sheet and capillary membranes: After extrusion, our membrane can be immediately processed on annealing and stretching lines that create the final porous form.
Microporous membranes produced via dry stretch have substantially elliptic shaped pores elongated in machine direction of membrane.
Typical applications for dry stretch capillary membranes are blood oxygenation and gas transfer.