SOLVENT-INDUCED CRYSTALLIZATION OF ISOTACTIC POLYPROPYLENE IN CYCLOHEXANE AT DIFFERENT TEMPERATURES

The process of solvent-induced crystallization of smectic polypropylene in cyclohexane was investigated at three temperatures: 15, 25 and 35-degrees-C. At the lowest temperature the process of sorption is non-Fickian, going towards diffusion-controlled crystallization. At this temperature it is possible to distinguish two stages in the process of crystallization: in the first stage a fraction of the amorphous phase transforms into a more ordered phase, while in the second stage the crystallization of the smectic phase occurs. On increasing the temperature, the first stage becomes shorter, and at 35-degrees-C it is not possible to seperate the two stages. The higher the temperature, the more effective is the transformation of the smectic into the monoclinic phase.