Numerical Study of Melt-Spinning Dynamic Parameters and Microstructure Development with Ongoing Crystallization

Area of Science:

• Materials Science
• Polymer Engineering
• Computational Fluid Dynamics

Background:

• Understanding fiber formation is crucial for developing advanced materials.
• Melt-spinning processes involve complex interplay of fluid dynamics and crystallization kinetics.
• Previous models often simplified the multi-physics involved in fiber spinning.

Purpose of the Study:

• To numerically simulate the melt-spinning process for nascent fibers.
• To analyze changes in crystallization, mechanical, and tensile properties.
• To investigate the influence of various spinning parameters on fiber characteristics.

Main Methods:

• Utilized a fluid dynamics two-phase model within the POLYFLOW environment.
• Integrated Nakamura crystallization kinetics with process parameters, stretch-induced crystallization, and viscoelasticity.
• Incorporated filament cooling, gravity, inertia, and air resistance for comprehensive simulation.

Main Results:

• Successfully predicted temperature, velocity, strain rate, birefringence, and stress distributions in nylon 6 BHS and CN9987 fibers.
• Obtained fiber crystallinity variation patterns under different stretching rates.
• Determined the influence rules of inlet flow rate, winding speed, and extrusion temperature on fiber crystallization.

Conclusions:

• The developed model accurately captures the complex phenomena during melt spinning.
• Insights into crystallization paths and mechanical property changes offer optimization strategies.
• Provides guidance for the industrial preparation of high-performance fibers.