Evaluation of Strip-Processed Cotton Stalks as a Raw Material for Structural Panels

This study explores a novel method for processing cotton stalks—an abundant agricultural byproduct—into long strips that serve as sustainable raw material for engineered bio-based panels. To evaluate the effect of raw material morphology on panel’s performance, two types of cotton stalk-based panels were developed: one using long strips, maintaining fiber continuity, and the other using ground particles, representing conventional processing. A wood strand-based panel made from commercial southern yellow pine strands served as the control. All panels were bonded using phenol-formaldehyde resin and hot-pressed to a target thickness of 12.7 mm and density of 640 kg/m3. Their mechanical and physical properties were evaluated through internal bond, bending, thickness swelling, and water absorption tests. Both cotton stalk-based panels showed improved bonding performance compared to the control. The internal bond of the strip-based panel was nearly four times higher than that of the control, while the particle-based panel exceeded it by a factor of two. The strip-based panel showed approximately 15% lower bending stiffness than the wood strand-based panel, yet it surpassed it in load-carrying capacity by 5%. In contrast, the particleboard showed significantly lower bending performance than the strip-based and control panels, despite particle processing being a more conventional method. Both cotton stalk-based panels exhibited higher water absorption and thickness swelling than the wood strand panel. Overall, cotton stalk-based panels—particularly those using strip processing—show promising mechanical properties, suggesting potential applications in sheathing, furniture, and interior paneling. However, improvements in dimensional stability are needed for broader use.