In polymer blends, the crystallization of the dispersed semicrystalline component depends on the type and distribution of the nucleating heterogeneities and on the level of the dispersion. Either fractionated or coincident crystallization may result. In this study, the effect of compatibilizers on the crystallization of polyamide 6/isotactic polypropylene (PP) blends was investigated. The morphology was controlled with 10 wt% of four different commercial compatibilizers - PPgMAH, EBAgFA, SEBSgMAH, and E-EA-GMA - each leading to specific morphology and crystallization behavior. The compatibilized blends show more complex crystallization compared with the corresponding binary blends. In the compatibilized blends, the dispersed PA6 seems to crystallize coincidentally with PP, probably due to its small particle size. The crystallization of PP takes place at temperatures above the bulk value at all compositions in blends compatibilized with PPgMAH and blends without the compatibilizer. By contrast, in blends compatibilized with EBAgFA, SEBSgMAH, and E-EA-GMA, the crystallization takes place either at PP bulk temperature or over the temperature range of 76-87 °C at the cooling rate of 10 °C/min. The amount of the shift cannot be explained solely by the size of the PP dispersion.
- polymer blends