Non‐isothermal Crystallization Kinetics, Thermal, and Rheological Behavior of Linear/Branched Polypropylene Blends

Abstract

This work aims at evaluating the rheological and thermal properties and non‐isothermal crystallization kinetics of blends of linear homopolymer polypropylene (HPP) and branched polypropylene (BPP). Two linear polypropylene's of different melt flow index (MFI) are used: H301 (10 g per 10 min) and H604 (1.5 g per 10 min); and one BPP (2 g pr 10 min). The rheological result shows that the H301/BPP blends have an increase in complex viscosity proportional to the addition of BPP amount, while for the H604/BPP blends, it is observed a higher influence of H604 on rheological properties. With the addition of 25 wt% of BPP, the strain hardening behavior is observed in the extensional rheology tests of the polymer blend. The DSC results show that the melt temperature and the crystallinity content in blends with BPP are affected by the molecular weight (MW) of the linear polymer. Results suggest that Pseudo‐Avrami/Jeziorny and Mo models can be used to predict the experimental results of crystallization kinetics of the blends with sufficient precision for all systems studied, regardless of MW. Therefore, it is possible to use the blends of HPP/BPP in processes that demand a combination of rheological properties, such as high strain hardening, and fast crystallization.