Fabrication and characterization of lignocellulosic coconut and energy reed straw-reinforced methylene diphenyl diisocyanate-bonded sustainable insulation panels

The use of renewable environmental resources and plastics that can be returned to the biological cycle shows a new direction in the application of composite building materials. This study investigated the potential and strengthening effects of developing composite panels from coconut materials (CM) and reed straw (RS) particles in the presence of methylene diphenyl diisocyanate (MDI). Five composite panels with 100:0, 60:40, 50:50, 40:60, and 0:100% proportions were produced. The nominal density was 600 kg/m3 and the dimensions were 400 × 400 × 8 mm3. The panels were produced by hot-pressing for a total of 10 min at a maximum pressure of 7.2 MPa and at 135 degrees, and then slowly cooled at room temperature. The following experiments were performed: mechanical, physical and morphological properties, thermal conductivity, FTIR (Fourier transform infrared spectroscopy), and EDX (Energy disruptive X-ray). The study gave the following results: the thermal conductivity of the coir and reed panels is competitive with the thermal insulation capacity of similar natural-based insulation materials, and is close to the values of other mineral and plastic-based insulation materials. The values of thermal conductivity coefficient ranged from 0.08 to 0.10 W/(mK). Only reeds (MDI_1) boards have better results than coconut materials. Among the mechanical properties, flexural strength and internal bonding strength increased proportionally with the increase in the amount of coconut. The Young's modulus reached its maximum in the case of a 50–50% coir-reed mixture. The best values of the panels are: 6.33 MPa for flexural strength, 1.83 GPa for Young's modulus and 0.36 MPa for internal bonding strength. The morphological recordings confirmed the proper mixing and binding of the lignocellulosic materials in the composite. FTIR tests proved the successful chemical interactions. The findings support the possibility of creating a promising, environmentally friendly building material.