INFLUENCE OF MOLECULAR WEIGHT ON BREAKING OF MELT SPINNING

Abstract

A melt spinning experiment has been carried out to correlate breaking take up velocity with the molecular weight and to study the effect of melt temperature, ambient temperature and apparatus on the correlation. Samples chosen for study were ten iso-polypropylene samples having widely different molecular weight. The shape of breaking part and the birefringence of breaking filament have been measured. The results were as follows:(1) A maximum in breaking take up velocity occurred in a certain value of molecular weight. A molecular weight in the maximum breaking takes up velocity increased with an increase in melt temperature. On the other hand, a strong correlation was observed between maximum breaking take up velocity and ambient temperature, and maximum breaking takes up velocity increased with an increase in ambient temperature up to 30°C. The effect of ambient temperature was closely related to the shape of breaking part.(2) Breaking behavior was not affected very much by a type and scale of apparatus. The deformation length of breaking part increased with an increase in melt temperature and ambient temperature, and decreased with an increase in molecular weight. The shape of breaking part was affected by birefringence of breaking filament in low molecular weight, but in high molecular weight it was influenced by other factor, such as entanglement.