Interfacial Interaction and Sintering Mechanism of Cellulose/Polylactic Acid Composites in Selective Laser Sintering:...

Area of Science:

• Materials Science
• Polymer Science
• Nanotechnology

Background:

• Polylactic acid (PLA) is a biodegradable polymer used in selective laser sintering (SLS).
• The atomic-level sintering mechanisms of plant-fiber-reinforced PLA are not well understood.
• Understanding these mechanisms is crucial for optimizing composite powder formulation for SLS.

Purpose of the Study:

• To investigate the sintering behavior and interfacial interactions of cotton stalk cellulose/PLA nanocomposites using all-atom molecular dynamics simulations.
• To determine the effect of cellulose content on PLA sintering mechanisms at the atomic level.
• To identify the optimal cellulose content for enhanced interfacial bonding and chain mobility in PLA composites for SLS.

Main Methods:

• All-atom molecular dynamics simulations were employed.
• The study simulated nanocomposites with varying cellulose content (0-20 wt%).
• Analyses included atomic displacement and radius-of-gyration to assess chain behavior.

Main Results:

• Nanoparticle coalescence occurred in three stages: van der Waals contact, neck formation, and interfacial densification.
• Cellulose content showed a non-monotonic effect on interfacial bonding.
• Optimal interfacial bonding and chain mobility were observed at 15 wt% cellulose, forming a continuous hydrogen-bond network.
• Excess cellulose (20 wt%) led to aggregation, disrupting continuity and hindering chain diffusion.

Conclusions:

• 15 wt% cellulose is the optimal content for enhanced interfacial bonding and chain mobility in cellulose/PLA nanocomposites for SLS.
• Cellulose acts as a scaffold, directing PLA chain extension and migration at optimal loading.
• These findings provide atomistic criteria for designing cellulose/PLA composite powders for improved SLS processing.