PolySTRAND Model of Flow-Induced Nucleation in Polymers

Area of Science:

• Polymer science
• Materials science
• Thermodynamics

Background:

• Flow-induced nucleation is critical in polymer processing.
• Existing models struggle with polydisperse systems and complex flow dynamics.
• Understanding nucleation mechanisms is key to controlling polymer morphology.

Purpose of the Study:

• To develop a thermodynamic continuum-level model for flow-induced nucleation in polymers.
• To enable accurate computational process modeling of polymer crystallization.
• To account for molecular origins and dynamics in polydisperse systems.

Main Methods:

• Developed the polySTRAND thermodynamic continuum model.
• Incorporated molecular origins to capture flow and nucleation dynamics.
• Modeled effects of processing parameters: flow rate, temperature, and molecular weight distribution.

Main Results:

• The polySTRAND model accurately captures variations with key processing parameters.
• Under strong flow, longer polymer chains are over-represented in the nucleus.
• Demonstrated superexponential nucleation rate growth with increasing shear rate, matching experimental observations.

Conclusions:

• PolySTRAND provides a robust framework for modeling flow-induced nucleation in polydisperse polymers.
• The model's molecular basis allows for accurate prediction of nucleation behavior under various processing conditions.
• Findings highlight the significant role of chain length distribution in flow-induced nucleation dynamics.