Development and characterization of sustainable agglomerated composites formulated from castor polyurethane resin and reinforced with rice husk

The current accelerated development of industrial and agricultural production has intermittently generated a large amount of waste. One of these residues is the rice husk, which represents 20% of the total volume of the grain produced. It is a lignocellulosic material that can be used as a reinforcement for composite materials. In turn, castor oil-based polyurethane resin is a triglyceride extracted from the seed, widely used to replace synthetic resins that are more aggressive to the environment. Thus, the objective of this study was to obtain a sustainable agglomerated composite based on rice husk and castor oil polyurethane resin. The samples were obtained by cold molding according to a 2 k (DoE) factorial design, the matrix/reinforcement volume fraction and the molding volume being the factors studied. The composite obtained was tested according to NBR 14,810, used for medium-density composites. Density, swelling, water absorption and resistance to flexion were evaluated. The results obtained allow us to classify the composite as low density, with values below 640 kg/m 3 according to the A 208.1 standard. Regarding the mechanical behavior, the composite does not meet the standard NBR 14,810 for medium density but meets the standard A 208.1 being classified as low-density LD-1 and LD-2. Graphical abstract