Draw resonance in polypropylene melt spinning

An attempt is made to gain better physical insight on the draw resonance phenomenon occurring during melt spinning of polypropylene (PP). An experimental study is first carried ouit to determine effects of spinning variables and material parameters on draw resonance, using two PRO-FAX PP resins and one PRO-FAX/LDPE blend. Based on the experimental observations, our view on the cause of draw resonance is presented. With this new concept, we are able to explain various aspects of the draw resonance phenomenon observed experimentally during melt spinning of PRO-FAX PP resins. It is concluded that the extensional viscosity versus strain relationship, as determined by an extensional rheometer, is one of the most valuable rheological measurements in analyzing flow instability occurring during polymer processing operations that utilize extensional flows.