Understanding the Mechanisms Behind Increased Load Transfer in BMI-flCNT Composites Using Molecular Dynamics

Area of Science:

• Materials Science
• Computational Materials Science
• Aerospace Engineering

Background:

• Deep-space exploration requires lightweight, high-strength aerospace materials to minimize payload mass.
• Polymer matrix composites (PMCs) with carbon-based reinforcements like carbon nanotubes (CNTs) are promising for aerospace applications.
• The mechanical performance of PMCs is often limited by weak interfaces between the matrix and reinforcements.

Purpose of the Study:

• To investigate methods for strengthening the interfacial region in bismaleimide (BMI)/flattened carbon nanotube (flCNT) composites.
• To computationally assess the impact of chemical functionalization and interfacial cross-linking on composite mechanical performance using molecular dynamics (MD).
• To determine the relationship between the degree of functionalization, cross-linking, and flCNT pullout forces.

Main Methods:

• Utilized molecular dynamics (MD) simulations to model the interfacial region of BMI/flCNT composites.
• Virtually introduced functionalization of flCNTs and covalent cross-links between BMI and flCNTs.
• Predicted flCNT pullout forces as a function of functionalization degree and cross-link density.

Main Results:

• Both functionalization of flCNTs and interfacial cross-linking significantly enhance the interfacial strength of the BMI/flCNT composite.
• Higher degrees of functionalization were found to potentially degrade the overall material integrity.
• flCNT pullout forces directly correlate with the extent of functionalization and the number of interfacial cross-links.

Conclusions:

• Chemical functionalization and covalent cross-linking are critical for improving the interfacial strength of advanced aerospace composites.
• Optimizing the degree of functionalization is essential to balance strengthening effects and maintain material integrity.
• This research provides valuable physical insights into strengthening mechanisms for next-generation aerospace structural materials.