On which parameters does the viscosity of a polymer melt depend?

The viscosity of a polymer melt is influenced by several key parameters, and the correct choice reflects the complexity of this relationship. Viscosity is a measure of a fluid’s resistance to flow, and it is affected by the temperature because, as the temperature increases, the polymer chains gain more energy, leading to a reduction in viscosity.

Shear rate also plays a significant role in determining viscosity, particularly for non-Newtonian fluids, which many polymer melts are. A higher shear rate can lead to a decrease in viscosity due to the alignment of polymer chains in the direction of flow.

Molecular weight is another critical parameter; higher molecular weight typically corresponds to increased viscosity, as longer polymer chains result in greater entanglement and resistance to flow.

The combination of these three parameters—temperature, shear rate, and molecular weight—offers a comprehensive view of how the viscosity of polymer melts behaves. Each factor contributes to the complex flow characteristics of these materials, making it essential to consider all three when analyzing viscosity in polymer processing and applications.