Comparative study of structure development in melt spinning polyolefin fibers: Polyethylene, polypropylene, polybutylene, poly-4-methylpentene-1

A comparative study of crystallization and orientation development in melt spinning is presented for four polyolefins high density polyethylene(PE), polypropylene(PP), polybutylene(PB-1), and poly-4-methylpentene-1 (P4MP). Melt spun filaments are characterized by wide angle x-ray diffraction(WAXS), birefringence and differential scanning calorimetry(DSC) measurements. Polymorphism (multiple crystalline states) is noted in the filaments of polybutylene which exhibits aging from one form to another as well as in polypropylene. The orientation of flexible chains in the melt state is well known to be determined by the stress field. The crystalline orientation of the solidified crystalline filaments as a function of spinline stress is found by WAXS to be highest for the P4MP and lowest for the PE. Birefringences of the melt spun PE fiber are however higher than PP or PB-1 and P4MP which had the lowest values when comparisons are made at the same spinline stress.