Polimery 1998, No 10, 579
The melt-blow or pneumothermal technique is applied to pro duce nonwoven fibers in a single step directly from polymer granulate, usually fiber-forming PP. The effect of operating parameters on the properties of fibers (average diameter, diameter distribution, crystallinity, birefringence) and nonwoven fabrics (strength, air-flow, resistance, pore size) is discussed. High process temperatures (350—390°C) and large volumes of hot compressed air used make melt-blowing an energy-consuming technique. Reported data and Authoress' own works allow to identify two major R&D directions targeted at increasing the melt-flow index, i.e., reducing the processing temperature of PP. Developing of new PP types by metallocene-catalyzed polymerization and modification of existing PP types by addition of thermal degradation promoters assisting the production of fabrics. The Rother method addition of radical initiators, especially 2,2-azodiisobutyronitrile, is advisable.
Keywords: pneumothermal processing of polypropylene, effect of pneumothermal processing parameters on properties of fabrics, properties of metallocene- catalyzed polypropylene, radical initiators affecting MFI of polypropylene