Analysis of crystallization during polypropylene melt-blown fiber formation

Melt-blown nonwovens with randomly distributed micron fibers are widely used because of their excellent properties such as high porosity and high filtration efficiency. It is necessary to study the crystallization behavior of the polymer during the melt-blowing process because crystallization affects the formation and properties of the melt-blown fibers. In this study, the nonisothermal crystallization under high-speed cooling conditions and the isothermal crystallization on the collector in the melt-blowing process were investigated. The thermal history of polypropylene during the melt-blowing process was restored by flash differential scanning calorimetry tests. The results showed that the polymer hardly crystallized during the high-speed cooling process from the spinneret to the collector in the case of considering the temperature. The air pressure promoted the crystallinity of melt-blown fibers. The shear effect of the airflow field was considered the main factor affecting the crystallization of melt-blown fibers. The results were beneficial to the establishment of the melt-blowing micro-theoretical model and the control of the final performance of the melt-blown fibers.