Synthesis and properties of reed-based polyurethane (PU) coating

The reuse of agricultural waste and the development of bio-based materials are the main strategies for solving the global energy crisis and environmental problems. Agricultural waste reeds containing natural nano-silica (SiO2) were liquefied with PEG-400, Castor oil, and acid to produce reed-based polyols (R–P). The result shows that the liquefied product is a polyol with a hydroxyl value of 171 mgKOH/g, a viscosity of 1.221 Pa S, the number average molecular weight (Mn) of 1.202 kg/mol. Then reed-based two-component polyurethane emulsion (R-T-PU) and reed-based one-component waterborne polyurethane emulsion (R-O-WPU) with good glossiness and excellent mechanical properties were prepared. Because of the natural nano-SiO2 in reed and castor oil, the coatings exhibit excellent mechanical properties and hydrophobicity. The results show that the series of reed-based polyurethane has excellent mechanical properties, a maximum hardness of 6H, good hydrophobic effect, a maximum contact angle of 109°, high thermal stability, and a maximum initial decomposition temperature can reach 299.1 °C. Therefore, the environmental protection bio-based polyurethane coating with excellent properties can be prepared with the reed, which is expected to replace fossil resources. It provides an experimental basis for the high-added-value utilization of reed.