Stirring Induced Solution Crystallization of Cis-1,4-Polybutadiene

The stirring induced solution crystallisation behaviour of cis-1,4-polybutadiene polymerized with rare-earth catalyst (Ln--PB) has been studied by electron microscope, DCS and GPC. It has been found that when 0.5% Ln--Pb toluene solution was stirred at a temperature within the range of --15 deg to --79 deg C with a speed of 180 rpm, a kind of white swollen thread-like 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 deg C, 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. 6 ref.--AA