Morphology-Controlled Rheological and Non-Isothermal Crystallization Behaviors in Immiscible Polypropylene/High Density Polyethylene Blends

Abstract

Understanding the correlation between morphology and the fundamental behavior of blends is crucial for tailoring their properties. This study investigated the effects of phase morphology on mechanical performance, rheology, and non-isothermal crystallization kinetics of immiscible polypropylene (PP)/high-density polyethylene (HDPE) blends. Nanometer-scale HDPE phases dispersed within PP, co-continuous phases, and micrometer-scale PP phases dispersed within HDPE were formed at 75/25, 50/50, and 25/75 PP/HDPE weight ratios, respectively. Mechanical results indicated that the co-continuous morphology dissipated energy more efficiently than the matrix-dispersed morphology. Rheological results showed that nanometer-scale dispersion significantly enhanced the blend elastic modulus through the restriction effect at the interfaces. Non-isothermal crystallization kinetics were analyzed using Jeziorny-modified Avrami, Ozawa, Mo, and Kissinger models. Due to HDPE’s heterogeneous nucleation effect, the crystallization temperature of PP was elevated, and the crystallization rate of the blend also increased with higher HDPE content. Furthermore, the blend with the 25/75 PP/HDPE exhibited a higher crystallization rate than neat HDPE, as the interfacial boundaries facilitated the alignment of HDPE chains. The higher crystallization activation energy calculated in the 75/25 PP/HDPE blend suggested that nanometer-scale dispersion imposed a more significant restriction on crystal growth compared to micrometer-scale dispersion.

Citation

Zhan, Ke; Wang, Pixiang; Wang, Xueqi; Li, Xiaomeng; Liu, Shaoyang; Elder, Thomas; Via, Brian; Tang, Chuanbing; Peng, Yucheng. 2024. Morphology-Controlled Rheological and Non-Isothermal Crystallization Behaviors in Immiscible Polypropylene/High Density Polyethylene Blends. Macromolecular Chemistry and Physics e00147.