Energy losses in ultrafiltration hollow fibers: Effect of shape

Mechanical and dielectric relaxation of ultrafiltration hollow fibers were studied by thermally stimulated creep and current, and differential scanning calorimetry. The high sensitivity of thermally stimulated techniques shows 8 relaxations and/or transitions between −150 and 350°C (degradation). Not all are related to the intrinsic nature of the material—indeed, 4 of them can be directly related to the shape of the membrane (porosity, diameters, spinning conditions, etc.). Molecular mechanisms of these phenomena are discussed.