Weld Formation Between Polymer Films Prepared at Different Temperatures: Insights from Molecular Dynamics...

Area of Science:

• Polymer Science
• Materials Science
• Computational Chemistry

Background:

• Fused Filament Fabrication (FFF) Additive Manufacturing (AM) relies on successful polymer welding.
• Understanding the fundamental mechanisms of polymer weld formation is crucial for optimizing AM processes.

Purpose of the Study:

• To investigate the early stages of polymer weld formation using Molecular Dynamics (MD) simulations.
• To analyze the influence of initial temperature differences on the welding process and weld strength.

Main Methods:

• Molecular Dynamics (MD) simulations were employed to model the interaction between two polymer films.
• Simulations considered films prepared at temperatures above and below the glass transition temperature.
• Analysis focused on surface interactions, heat transfer, and polymer interdiffusion.

Main Results:

• Welding progresses through three distinct stages: surface approach, surface adjustment, and interdiffusion.
• Initial temperature differences influence interfacial temperature and polymer conformation.
• Asymmetric heat transfer occurs upon contact; environmental heat exchange mitigates temperature effects before interdiffusion.
• Isolated systems show earlier interdiffusion onset when films have different initial temperatures.

Conclusions:

• Thermal relaxation across the interface is critical for polymer weld formation.
• Controlling thermal conditions during welding can enhance weld strength.
• MD simulations provide valuable insights into polymer welding mechanisms relevant to AM.