Resíduo agroindustrial de andiroba na produção de painéis MDP: estudo de melhoria das propriedades físico-mecânicas

Abstract

The residue generated from the extraction of andiroba oil (Carapa guianensis) is an abundant lignocellulosic biomass in the Amazon region with potential application in the production of composite materials. However, the presence of residual oil and other extractive compounds may impair the interfacial adhesion between lignocellulosic particles and the polymer matrix, thereby reducing the physical and mechanical performance of the resulting materials. In this context, the present study aimed to evaluate the effect of physicochemical treatments applied to andiroba residue for the removal of residual oil, as well as to investigate the influence of the polyol/prepolymer ratio on the physical and mechanical properties of composites used in the manufacture of medium-density particleboards (MDP) produced with a castor oil-based bicomponent polyurethane resin. Initially, the residues were subjected to different treatment routes, and their effectiveness was assessed by low-field nuclear magnetic resonance (LF-NMR). The treatment consisting of an aqueous solution containing 20% surfactant showed the best performance, promoting the removal of approximately 57% of the residual oil present in the biomass. After defining the most efficient treatment condition, panels were produced using both treated and untreated residues, while maintaining a constant resin content of 30% of the total mass and varying the polyol/prepolymer ratios. Physical and mechanical characterization revealed that the treatment of the residue promoted significant reductions in water absorption (22.8%) and thickness swelling after 24 hours (32.4%), as well as overall average increases of approximately 250% in modulus of rupture (MOR) and 196% in modulus of elasticity (MOE) compared with panels produced using untreated residue. The results indicated that residual oil removal improved the interaction between the polymer matrix and the lignocellulosic particles, contributing to more efficient stress transfer at the interface. Although variations in the polyol/prepolymer ratio influenced panel performance, their effect was secondary when compared with the impact of residue treatment. It can be concluded that the physicochemical treatment of andiroba biomass is an effective strategy for valorizing this agro-industrial residue, expanding its potential application in the sustainable production of MDP panels and adding value to the andiroba production chain