Mechanical properties and superstructure of isotactic polypropylene fibersprepared by continuous vibrating zone-drawing

A continuous vibrating zone-drawing (CVZD) was applied to study the effect of vibration on the mechanical properties and superstructure of isotactic p olypropylene fibers. The CVZD treatment was a new drawing method by which t he fiber was continuously drawn at a rate of 0.5 m/min under vibration usin g the specially designed apparatus. The CVZD treatment was carried out in f ive steps at a drawing temperature of 150 degreesC and a frequency of 100 H z, and applied tensions increased step by step with processing in the range of 14.8 to 207 MPa. The obtained fiber had a birefringence of 0.0373, crys tallinity of 62.4%, tensile modulus of 17.6 GPa, and tensile strength of 1. 11 GPa. These values are higher than those of the continuous zone-drawn iso tactic polypropylene fiber previous reported. The vibration added to the fi bers during the zone-drawing was effective in developing amorphous orientat ion and improving the mechanical properties. (C) 2001 John Wiley & Sons. In c.