Effect of polymer viscosities on the fiber structure and membrane properties of polypropylene/polyethylene bicomponent hollow fibers

Polypropylene (PP) / Polyethylene (PE) bicomponent microporous hollow fiber membranes were prepared through the bicomponent melt spinning and drawing processes. Fibers of hollow shape were firstly prepared through the melt spinning process by introducing the air into the core part of the fiber cross-section. Annealing and drawing processes were applied to thus prepared fibers to furnish the membrane properties to the fibers. In this study, high and low molecular weight PP, HMwPP and LMwPP, were used. Viscosity of HMwPP was higher than that of PE, while viscosity of LMwPP was lower than that of PE. In the case of LMwPP/PE fibers, birefringence of PE component increased with take-up velocity and birefringence of LMwPP component was lower than that of PE component at all attainable take-up velocities. In HMwPP/PE fibers, birefringence of both components increased with take-up velocity at low take-up velocities. Birefringence of HMwPP component increased continuously with further increase of take-up velocity,...