Performance Evaluation of Medium Density Fiberboard for Structural Use: Influence of Melamine Content, Resin Content, and Density

Abstract

The feasibility of improving medium-density fiberboard (MDF) for structural applications was addressed by improving its mechanical and dimensional properties through modifications in resin formulation and board density. Melamine-urea-formaldehyde (MUF) resin was used as the adhesive, with three melamine substitution levels (25%, 27%, and 30%), resin contents ranging from 18% to 26% (based on oven-dry fiber weight), and target densities of 790, 820, and 850 kg/m³. The MDF bonded with MUF containing 30% melamine showed higher modulus of rupture (MOR) and water resistance indicated by lower thickness swelling (TS) and water absorption (WA) than those with 25% melamine. Increasing the resin content improved MOR and significantly reduced TS, with optimal performance at 26% resin content. Higher density positively affected mechanical properties and dimensional stability. The MDF with a density of 851 kg/m³ showed the best results in both MOR and WA, confirming its suitability for structural applications. The optimal formulation of 30% melamine content, 26% resin content, 1% hardener, 1% wax, and a density of 851 kg/m³ met the performance criteria for structural MDF. Notably, under these optimal conditions, the formaldehyde emission was 0.48 mg/L, satisfying stringent environmental standards.