Development and use of a turbidity analyzer for studying the solution crystallization of polyolefins

Cooling a solution of a crystalline polyolefin from 140°C to room temperature causes the dissolved polymer to crystallize. If a laser beam passes through this solution, the crystallization will cause the beam to scatter, which thereby decreases the intensity of the beam. With this principle, it is possible to follow the crystallization of polyolefins under controlled cooling. An instrument capable of doing these analyses was manufactured, and several different polyolefins were analyzed. The effect of the experimental parameters are illustrated for both cooling and reheating experiments. In addition, an interesting dependence on molecular weight was also observed for a series of metallocene polypropylenes.