Crystallization and crystal morphology of polymers: A multiphase-field study

Area of Science:

• Materials Science
• Computational Modeling
• Polymer Science

Background:

• Understanding polymer crystallization is crucial for material properties.
• Existing models may lack flexibility for complex systems like blends and composites.
• Microstructural evolution significantly impacts final material performance.

Purpose of the Study:

• To introduce a novel coarse-grained model for polymer crystallization.
• To investigate the influence of carbon fibers on crystallization morphology and kinetics.
• To analyze the impact of cooling rates and initial grain distribution.

Main Methods:

• A multiphase-field approach combined with Nakamura's kinetic equation and heat conduction.
• Simulation of microstructural evolution under isothermal and non-isothermal conditions.
• Application to neat PA6 and PA6/carbon fiber composite systems.

Main Results:

• The model qualitatively agrees with experimental relative crystallinity data.
• Carbon fibers promote more homogeneous crystal morphology and vertical grain growth.
• Higher initial crystal fraction and fiber thermal conductivity contribute to observed effects.

Conclusions:

• The developed model effectively simulates polymer crystallization in neat and composite systems.
• Carbon fibers act as nucleation sites, influencing crystal morphology due to geometrical and thermal effects.
• Observed vertical growth is attributed to surface constraints rather than intrinsic growth direction.