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The role of crystallization kinetics in the development of the structure and properties of polypropylene filaments
Author(s) -
Lu F. M.,
Spruiell J. E.
Publication year - 1993
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1993.070490409
Subject(s) - crystallization , materials science , kinetics , polypropylene , nucleation , differential scanning calorimetry , rheology , copolymer , polymer chemistry , chemical engineering , ethylene , polymer , composite material , thermodynamics , chemistry , organic chemistry , catalysis , physics , quantum mechanics , engineering
The processing, structure, and properties of filaments melt spun from three polypropylenes with similar rheology but substantially different crystallization kinetics were studied. The crystallization kinetics of the homopolymer was increased by the addition of a nucleating agent, whereas slower crystallization kinetics was obtained through a small amount of random copolymerization with ethylene. The relative crystallization kinetics of these three polymers was examined under quiescent conditions using differential scanning calorimetry. The technique of on‐line diameter and birefringence measurement was used to show the characteristics of the on‐line crystallization of the different resins. It was found that changing the quiescent crystallization kinetics by either the addition of a nucleating agent or through copolymerization with ethylene can produce profound effects on the structure and properties of polypropylene as‐spun filaments when they are spun under relatively low stress and low takeup velocity conditions. Higher takeup velocities and spinline stresses reduce the effect of differences in quiescent crystallization due to the influence of on‐line stress‐induced (molecular orientation‐enhanced) crystallization. © 1993 John Wiley & Sons, Inc.