SHEATH-CORE DIFFERENCES CAUSED BY RAPID THERMOXIDATION DURING MELT BLOWING OF FIBERS

In melt-blown fibers there exists a radial variation in molecular weig ht. This difference is caused by the very rapid (<25 ms) diffusion and thermoxidation reaction of oxygen with the polymer in the fiber sheat h. The core remains unaffected. The difference in molecular weight mak es the fibers suitable for thermal bonding. A technique based on intri nsic viscosity measurements was developed for measuring sheath and cor e molecular weights. A complex mathematical model was developed to acc ount for rapid diffusion and thermoxidation. The experimental molecula r weight measurements are well-fit by the model.