Coniferous Bark as Filler for Polylactic Acid-Based Biocomposites

Area of Science:

• Materials Science
• Polymer Science
• Composite Materials

Background:

• Wood-polymer composites (WPCs) are increasingly used, with fillers significantly influencing their properties.
• Coniferous bark is an abundant, underutilized biomass resource with potential as a WPC filler.
• Understanding bark's impact on WPC properties is crucial for sustainable material development.

Purpose of the Study:

• To investigate the feasibility of using coniferous bark as a filler in polylactic acid (PLA) based WPCs.
• To evaluate the effect of bark filler content and particle size on WPC properties.
• To compare the performance of bark-filled WPCs with those filled with coniferous sawdust.

Main Methods:

• Six variants of bark-PLA WPCs were manufactured with varying bark filler content and particle sizes.
• Mechanical properties (MOR, MOE) and physical properties (TS, WA) were measured after water immersion.
• Water contact angles and surface free energy were analyzed.
• Statistical analysis was performed to determine the significance of filler type and content.

Main Results:

• Bark-filled WPCs exhibited significantly lower thickness swelling (TS) and water absorption (WA) compared to sawdust-filled composites.
• Bark filler led to reduced modulus of rupture (MOR) and modulus of elasticity (MOE), with smaller particles causing greater reductions.
• Bark-filled composites showed lower water contact angles and surface free energy.
• Filler content was the most significant factor affecting WPC properties, followed by filler type.

Conclusions:

• Coniferous bark is a viable filler for PLA WPCs, improving water resistance properties.
• The use of bark filler negatively impacts mechanical strength, necessitating optimization of filler content and particle size.
• Filler content and type are critical parameters controlling the performance of bark-based WPCs.