Eco-Friendly Board from Banana Trunk Residues with Poly(Vinyl Alcohol)/Boric Acid

The increasing demand for wood-based products and environmental concerns have led to an increasing trend toward raw materials for board production. In this study, boards were produced using banana trunk as filler material and poly-(vinyl alcohol) (PVA)/boric acid (BA) as binder. The effects of varying PVA/BA (1/1-1/3) and filler (DM)/binder-(B) ratios (3/1-6/1) determined as experimental parameters on the physical (density, water absorption, and thickness swelling tests), mechanical (three-point bending tests), flame retardant properties (limiting oxygen index (LOI) analysis), and structural analysis (FTIR, TGA and SEM) of boards were investigated. In the determination of physical properties, it was determined that the densities of the samples were in the range of 790-1770 kg/m³ and that the density values generally increased with the increase in the amount of boric acid. Experimental findings showed that the compositions of both binder and filler significantly affected the water absorption and swelling properties of boards. Mechanical test results showed that reducing the PVA ratio (increasing BA) increased the mechanical strength of the boards and that the PVA/BA-1/2 composition had 88% higher strength (48.06 MPa) compared to PVA/BA-3/1. Mechanical strength values for different DM/B plates were determined to be between 5.2 and 15.44 MPa. In addition, very high flame retardancy values were obtained by increasing the boric acid content, with LOI values reaching up to 55. Structural analyses revealed that the thermal and mechanical properties of the boards are a result of the interaction between PVA/BA esterification and the banana trunk. Banana tree trunks, BA, and PVA can be used as sustainable raw materials for the production of environmentally friendly boards with improved mechanical and fire resistance properties.