Effect of Lignin or Lignosulfonate Addition on the Fire Resistance of Areca (Areca catechu) Particleboards Bonded with Ultra-Low-Emitting Urea-Formaldehyde Resin

Abstract

As a way to accommodate the rising demand for “green” wood-based products, agricultural waste from Areca (Areca catechu) nut farms, which is generally burned on-site, can be used to raise the value of alternative lignocellulosic raw materials. This research aimed to investigate and evaluate the effect of technical lignin (kraft lignin or lignosulfonate) addition on particleboard properties from areca bonded with ultra-low-emitting urea formaldehyde (UF) resin. The physical properties, mechanical properties, and fire resistance of the laboratory-made particleboards were tested and evaluated in accordance with the applicable Japanese industrial standards (JIS). The highest density of 0.84 g/cm3 was determined for the laboratory boards, bonded with an adhesive mixture of UF resin and kraft lignin with three washing treatments. The lowest moisture content of 9.06%, thickness swelling of 71.16%, and water absorption of 129.17% were determined for the boards bonded with lignosulfonate with three washing treatments, with commercial lignin, and with lignosulfonate with five washing treatments, respectively. The highest MOR and MOE values, i.e., 113.49 kg/cm2 and 10,663 kg/cm2, respectively, were obtained for the particleboards bonded with lignosulfonate with five washing treatments. Interestingly, all laboratory boards exhibited good fire resistance following the UL-94 standard. Based on the gas torch test, the lowest weight loss of 16.7% was determined in the boards fabricated with lignosulfonate with five washing treatments. This study demonstrated that adding lignin-based fire retardants represents a viable approach to producing lignocellulosic composites with enhanced fire resistance and a lower carbon footprint.