In this work

the stirring induced solution crystallization behaviour of cis-1

4-polybutadiene polymerized with rare-earth catalyst (Ln-PB) has been studied by electron microscope

DSC and GPC. It has been found that when 0.5% Ln-PB toluene solution was stirred at a temperature within the range of-15° to-79℃ with a speed of 180 rpm

a kind of white swollen thread-llke substance wound around the stirrer was formed. It was seen under electron microscope that this swollen thread-Like substance consisted of fibrillar crystals of Ln-Pb parallel to each other.The amount of Ln-Pb wound around the stirrer increased with the decrease in crystallization temperature until a maximum was reached at about-65℃

then it decreased with the decrease in crystallization temperature.However

the higher the crystallization temperature

the higher the average molecular weight and the narrower the molecular weight distribution of Ln-PB which wound around the stirrer.Therefore

Ln-PB sample may be fractionated by stirring its dilute solution at a series of crystallization temperatures.