Mechanical, Physical, and Sound Absorption Properties of Wood-Based Composites Made from Krajood (Lepironia articulata) Using Isocyanate as Binder

Abstract

This study investigates the mechanical, physical, acoustic, andmorphological properties of composites prepared from Krajood (Lepironiaarticulata) fibers bonded with isocyanate binder. The wood-based werefabricated with different fiber lengths (10 mm, 20 mm, and mixed lengths)and varied fiber-to-binder ratios of 80:20, 85:15, and 90:10 wt% using acompression molding process. The results showed that tensile strength andsurface hardness significantly improved in composites with mixed fiberlengths, especially at an optimized fiber-to-binder ratio of 85:15 wt%.Additionally, water absorption and thickness swelling tests showed thathigher binder content and shorter fibers effectively reduced moisture uptake,enhancing dimensional stability. Composites containing mixed fiber lengthsshowed the lowest water uptake and swelling values due to improved fiberpacking density. Sound absorption analysis revealed superior acousticperformance at mid-range frequencies (500–2000 Hz) for composites with 20mm fibers and mixed fibers, attributed to increased internal porosity and fiberscattering. Optical microscopy analysis demonstrated that composites withmixed fiber lengths displayed the most uniform and compact surfacestructures, with minimal fiber pull-out and porosity, suggesting enhancedfiber dispersion and matrix encapsulation. These findings highlight the criticalrole of fiber length distribution and binder ratio in tailoring compositeproperties. The optimized Krajood composites demonstrated a favorablebalance between mechanical integrity, dimensional stability, and acousticefficiency, highlighting their potential for sustainable applications such as ecofriendlyinterior components, elderly-supportive furniture, and acousticpanels.